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  • 101
    ISSN: 0749-503X
    Keywords: Pichia pastoris ; methylotrophic yeasts ; dihydroxyacetone kinase ; DNA sequencing ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Dihydroxyacetone kinase (DAK) is essential for methanol assimilation in methylotrophic yeasts. We have cloned the DAK gene from Pichia pastoris by functional complementation of a mutant that was unable to grow on methanol. An open reading frame of 1824 bp was identified that encodes a 65·3 kDa protein with high homology to DAK from Saccharomyces cerevisiae. Although DAK from P. pastoris contained a C-terminal tripeptide, TKL, which we showed can act as a peroxisomal targeting signal when fused to the green fluorescent protein, the enzyme was primarily cytosolic. The TKL tripeptide was not required for the biochemical function of DAK because a deletion construct lacking the DNA encoding this tripeptide was able to complement the P. pastoris dakΔ mutant. Peroxisomes, which are essential for growth of P. pastoris on methanol, were present in the dakΔ mutant and the import of peroxisomal proteins was not disturbed. The dakΔ mutant grew at normal rates on glycerol and oleate media. However, unlike the wild-type cells, the dakΔ mutant was unable to grow on methanol as the sole carbon source but was able to grow on dihydroxyacetone at a much slower rate. The metabolic pathway explaining the reduced growth rate of the dakΔ mutant on dihydroxyacetone is discussed. The nucleotide sequence reported in this paper has been submitted to GenBank with Accession Number AF019198. © 1998 John Wiley & Sons, Ltd.
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  • 102
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 869-875 
    ISSN: 0749-503X
    Keywords: calmodulin ; CMD1 ; ALG1 ; K. lactis ; EF hand ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The KlCMD1 gene was isolated from a Kluyveromyces lactis genomic library as a suppressor of the Saccharomyces cerevisiae temperature-sensitive mutant spc110-124, an allele previously shown to be suppressed by elevated copy number of the S. cerevisiae calmodulin gene CMD1. The KlCMD1 gene encodes a polypeptide which is 95% identical to S. cerevisiae calmodulin and 55% identical to calmodulin from Schizosaccharomyces pombe.Complementation of a S. cerevisiae cmd1 deletion mutant by KlCMD1 demonstrates that this gene encodes a functional calmodulin homologue. Multiple sequence alignment of calmodulins from yeast and multicellular eukaryotes shows that the K. lactis and S. cerevisiae calmodulins are considerably more closely related to each other than to other calmodulins, most of which have four functional Ca2+-binding EF hand domains. Thus like its S. cerevisiae counterpart Cmd1p, the KlCMD1 product is predicted to form only three Ca2+-binding motifs. The KlCMD1 sequence has been assigned Accession Number AJ002021 in the EMBL/GenBank database. © 1998 John Wiley & Sons, Ltd.
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  • 103
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; adrenodoxin reductase ; mitochondria ; essential gene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A yeast gene was found in which the derived protein sequence has similarity to human and bovine adrenodoxin reductase (Nobrega, F. G., Nobrega, M. P. and Tzagoloff, A. (1992). EMBO J. 11, 3821-3829; Lacour, T. and Dumas, B. (1996). Gene 174, 289-292), an enzyme in the mitochondrial electron transfer chain that catalyses in mammals the conversion of cholesterol into pregnenolone, the first step in the synthesis of all steroid hormones. It was named ARH1 (Adrenodoxin Reductase Homologue 1) and here we show that it is essential. Rescue was possible by the yeast gene, but failed with the human gene. Supplementation was tried without success with various sterols, ruling out its involvement in the biosynthesis of ergosterol. Immunodetection with a specific polyclonal antibody located the gene product in the mitochondrial fraction. Consequently ARH1p joins the small group of gene products that affect essential functions carried out by the organelle and not linked to oxidative phosphorylation. © 1998 John Wiley & Sons, Ltd.
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  • 104
    ISSN: 0749-503X
    Keywords: pyrolysis mass spectrometry ; Fourier tranform infrared spectroscopy ; chemometrics ; quality assurance ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Two rapid spectroscopic approaches for whole-organism fingerprinting - pyrolysis mass spectrometry (PyMS) and Fourier transform infrared spectroscopy (FT-IR) - were used to analyse 22 production brewery Saccharomyces cerevisiae strains. Multivariate discriminant analysis of the spectral data was then performed to observe relationships between the 22 isolates. Upon visual inspection of the cluster analyses, similar differentiation of the strains was observed for both approaches. Moreover, these phenetic classifications were found to be very similar to those previously obtained using genotypic studies of the same brewing yeasts. Both spectroscopic techniques are rapid (typically 2 min for PyMS and 10 s for FT-IR) and were shown to be capable of the successful discrimination of both ale and lager yeasts. We believe that these whole-organism fingerprinting methods could find application in brewery quality control laboratories. © 1998 John Wiley & Sons, Ltd.
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  • 105
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 915-922 
    ISSN: 0749-503X
    Keywords: small GTP-binding proteins ; YPT1 ; YPT6 ; SSD1 ; SLY1 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ypt6p, the yeast homologue of human RAB6, is required for protein trafficking at elevated temperatures. Biochemical data provide evidence that Ypt6p plays a role in an early step(s) of the secretory pathway: from ER to Golgi, or from cis to medial Golgi, or both. Here we show that overexpression of YPT1 suppresses the growth and secretion defects of a ypt6 temperature-sensitive (ts) strain. SLY1-20, encoding a dominant mutant allele that suppresses the lethal effect of YPT1, also suppresses the growth defect of a ypt6 ts strain. Conversely, SSD1, isolated as a suppressor of ypt6 ts, can suppress the growth defect of a ypt1 ts allele. These data suggest that Ypt6p has some redundant function with Ypt1p. However, overexpression of Ypt6p is toxic to a ypt1 ts strain, although it does not affect the growth of wild-type cells, suggesting that Ypt6p may sequester proteins shared with Ypt1p. This genetic evidence confirms the conclusion that Ypt6p is involved in an early step of the secretory pathway. © 1998 John Wiley & Sons, Ltd.
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  • 106
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 977-984 
    ISSN: 0749-503X
    Keywords: aldose reductase ; catalytic mechanism ; coenzyme binding ; sequence comparison ; SDR enzymes ; structure-function relationship ; xylose reductase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Yeast xylose (aldose) reductases are members of the aldo-keto reductase family of enzymes which are widely distributed in a variety of other organisms. In yeasts, these enzymes catalyse the first step of xylose metabolism where xylose is converted to xylitol. In the past 16 years, xylose reductases from yeasts able to ferment or utilize xylose have been isolated and studied mainly because of their importance in xylose bioconversions. In recent years, genes encoding xylose reductases from several yeasts have been cloned and sequenced. A comparison of the primary sequences of yeast xylose reductases with the much better characterized human aldose reductase and human aldehyde reductase reveals that the yeast enzymes are hybrids between aldo-keto reductases and the short chain dehydrogenases/reductases families of enzymes. Why this is so and its evolutionary significance is presently not known. This short review will critically examine the structure and function information that can be gleaned from the sequence comparison. Several interesting questions arise from the sequence comparison and these can provide fruitful areas for further investigations. © 1998 John Wiley & Sons, Ltd.
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  • 107
    ISSN: 0749-503X
    Keywords: Candida albicans ; HIS4 ; complementation ; molecular biology tools ; topological marker ; amino acid biosynthesis general control ; PEX5 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have isolated the Candida albicans HIS4 (CaHIS4) gene by complementation of a his4-34 Saccharomyces cerevisiae mutant. The sequenced DNA fragment contains a putative ORF of 2514 bp, whose translation product shares a global identity of 44% and 55% to the His4 protein homologs of S. cerevisiae and Kluyveromyces lactis, respectively. Analysis of CaHIS4 sequence suggests that, similarly to S. cerevisiae HIS4, it codes for a polypeptide having three separate enzymatic activities (phosphoribosyl-AMP cyclohydrolase, phosphoribosyl-ATP pyrophosphohydrolase and histidinol dehydrogenase) which reside in different domains of the protein. A C. albicans his4 strain is complemented with this gene when using a C. albicans-S. cerevisiae-Escherichia coli shuttle vector, thus enabling the construction of a host system for C. albicans genetic manipulation. In addition, upstream of the sequenced CaHIS4 sequence, we have found the 3′-terminal half of a gene encoding a PEX5-like protein. The EMBL/DDJB/GenBank Accession Number of this sequence is AJ003115. © 1998 John Wiley & Sons, Ltd.
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  • 108
    ISSN: 0749-503X
    Keywords: yeast ; elongation factor-3 ; EF-3 ; homolog ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A paralog (intraspecies homolog) of the Saccharomyces cerevisiae YEF3 gene, encoding elongation factor-3, has been sequenced in the course of the yeast genome project, and identified by database searching; this gene has been designated HEF3. Bioinformatic and Northern blot analysis indicate that the HEF3 gene is not expressed during vegetative growth. Deletion of the HEF3 gene reveals no growth defects, nor any defects in mating or sporulation. A high copy 2μ clone of HEF3 was constructed, and was shown to be unable to complement a null allele of yef3. Finally, an in vitro assay for ribosome-stimulated ATPase activity was performed with isogenic HEF3 and Δhef3 strains; no difference in biochemical activity could be detected in these strains. From these results, we conclude that the HEF3 gene does not encode a functional homolog of YEF3. © 1998 John Wiley & Sons, Ltd.
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  • 109
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 623-631 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; bicarbonate ; meiosis ; sporulation ; respiration ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Meiosis and sporulation in the yeast Saccharomyces cerevisiae requires social communication, mediated by an extracellular factor which is secreted from cells during sporulation and accumulates in a cell density-dependent manner. We show here genetic and biochemical analyses supporting our conclusion that the extracellular factor is bicarbonate acting as an alkali to elevate extracellular pH. Sporulation defects of mdh1 (mitochondrial malate dehydrogenase) mutants and of wild-type cells at low density were rescued extracellularly by addition of bicarbonate or other alkaline solutions to raise medium pH. Addition of bicarbonate (or alkalization of medium) raised steady-state levels of mRNA in respiration-deficient mdh1 mutants and inhibited proliferation of wild-type cells at low density. These results indicate that the two conditions (respiration competency and high cell density), required for meiosis and sporulation, are essential for extracellular accumulation of bicarbonate and resulting alkalization of medium. © 1998 John Wiley & Sons, Ltd.
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  • 110
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 617-622 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; extracellular factor ; meiosis ; sporulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Meiosis and sporulation in the yeast Saccharomyces cerevisiae has been classically viewed as an example of unicellular, eukaryotic differentiation that occurs in response to nutritional starvation. We present evidence that S. cerevisiae produces an extracellular factor(s), called meiosis-promoting factor (MEP), that is required, in addition to starvation conditions, for efficient meiosis and sporulation. This factor is secreted and accumulates in a cell density-dependent fashion such that cells at a low density sporulate poorly under conditions in which cells at a high density sporulate efficiently. Conditioned medium from sporulating cells at a high density contains a small anionic molecule that has cytostatic activity and stimulates sporulation of cells at low density under a normal starvation condition. These results indicate that MEP-mediated social communication between cells is required for meiosis and sporulation. © 1998 John Wiley & Sons, Ltd.
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  • 111
    ISSN: 0749-503X
    Keywords: fission yeast ; gene deletions ; gene truncations ; overexpression studies ; epitope tagging ; polymerase chain reaction ; gene expression ; green fluorescent protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We describe a straightforward PCR-based approach to the deletion, tagging, and overexpression of genes in their normal chromosomal locations in the fission yeast Schizosaccharomyces pombe. Using this approach and the S. pombe ura4+ gene as a marker, nine genes were deleted with efficiencies of homologous integration ranging from 6 to 63%. We also constructed a series of plasmids containing the kanMX6 module, which allows selection of G418-resistant cells and thus provides a new heterologous marker for use in S. pombe. The modular nature of these constructs allows a small number of PCR primers to be used for a wide variety of gene manipulations, including deletion, overexpression (using the regulatable nmt1 promoter), C- or N-terminal protein tagging (with HA, Myc, GST, or GFP), and partial C- or N-terminal deletions with or without tagging. Nine genes were manipulated using these kanMX6 constructs as templates for PCR. The PCR primers included 60 to 80 bp of flanking sequences homologous to target sequences in the genome. Transformants were screened for homologous integration by PCR. In most cases, the efficiency of homologous integration was ≥50%, and the lowest efficiency encountered was 17%. The methodology and constructs described here should greatly facilitate analysis of gene function in S. pombe. © 1998 John Wiley & Sons, Ltd.
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  • 112
    ISSN: 0749-503X
    Keywords: Pichia pastoris ; expression vectors ; gene regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The budding yeast Pichia pastoris is an attractive system for exploring certain questions in cell biology, but experimental use of this organism has been limited by a lack of convenient expression vectors. Here we describe a set of compact vectors that should allow for the expression of a wide range of endogenous or foreign genes in P. pastoris. A gene of interest is inserted into a modified pUC19 polylinker; targeted integration into the genome then results in stable and uniform expression of this gene. The utility of these vectors was illustrated by expressing the bacterial β-glucuronidase (GUS) gene. Constitutive GUS expression was obtained with the strong GAP promoter or the moderate YPT1 promoter. The regulatable AOX1 promoter yielded very strong GUS expression in methanol-grown cells, negligible expression in glucose-grown cells, and intermediate expression in mannitol-grown cells. GenBank Accession Numbers are: pIB1, AF027958; pIB2, AF027959; pIB3, AF027960; pIB4, AF027961. © 1998 John Wiley & Sons, Ltd.
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  • 113
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 114
    ISSN: 0749-503X
    Keywords: Dipodascus (Endomyces) magnusii ; genetic transformation ; ribosomal DNA ; autonomous replicating sequence ; electroporation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have developed the first system for genetic transformation of the multinuclear yeast Dipodascus magnusii. The system is based on a dominant selectable marker and an autonomously replicating sequence. We have constructed a plasmid vector which contains a marker conferring resistance to zeocin and the segment of non-transcribed spacer of D. magnusii ribosomal DNA which supports the autonomous replication of plasmid DNA in yeast cells. Plasmid DNA has been transferred into D. magnusii cells by electroporation. The DNA sequence which is described in this article has been deposited in the EMBL data library under Accession Number Y14587. © 1998 John Wiley & Sons, Ltd.
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  • 115
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    Yeast 14 (1998), S. 847-852 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; 2 micron plasmid ; Flp ; DNA damage ; curing ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Powerful mutagenic screens of yeast Saccharomyces cerevisiae have recently been developed which require strains that lack the endogenous 2 micron plasmid (Burns et al., 1994). Here, we describe a simple and reliable method for curing yeast of the highly stable genetic element. The approach employs heterologous expression of a ‘step-arrest’ mutant of the Flp recombinase. The mutant, Flp H305L (Parsons et al., 1988), forms long-lived covalent protein-DNA complexes exclusively at 2 micron-borne recombinase target sites. In vivo, the complexes serve as sites of targeted DNA damage. Using Southern hybridization and a colony color assay for plasmid loss, we show that expression of the mutant enzyme results in the effective elimination of the 2 micron from cells. © 1998 John Wiley & Sons, Ltd.
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  • 116
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 985-1000 
    ISSN: 0749-503X
    Keywords: Mig1 repressor ; glucose repression ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A major mediator of glucose repression in yeast is Mig1, a zinc finger protein that binds to a GC-rich recognition sequence found upstream of many glucose-repressible genes. Because these Mig1 sites are found upstream of genes under different modes of regulation, we studied regulation of transcription mediated by an isolated Mig1 site placed upstream of a reporter gene under control of UASCYC1. The Mig1 site responded appropriately to glucose control and regulatory mutations, including snf1, reg1, cyc8, and tup1, mimicking the behavior of the SUC2 gene. Deletion of the MIG1-coding gene reduced but did not eliminate glucose repression mediated by the Mig1 site. Complete loss of repression was seen in a mig1 mig2 double mutant. When the UASCYC1 was replaced by UASADH1 in the reporter plasmid, the Mig1 site activated transcription under most conditions. Mutations of the two Mig1 binding sites in the SUC2 promoter resulted in loss of activation of SUC2 expression. These results suggest the presence of an unknown activator or activators that binds to the Mig1 site. The activator is not any of the proteins previously proposed to bind to this site, including Mig1, Mig2, Msn2, or Msn4. Band shift assays showed that Mig1 is the major protein in yeast cell extracts that binds to the Mig1 site in vitro. This binding is not regulated by glucose or mutations in CYC8 or TUP1. © 1998 John Wiley & Sons, Ltd.
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  • 117
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 1001-1006 
    ISSN: 0749-503X
    Keywords: succinate dehydrogenase ; SDH1 ; SDH1b ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Transformation of the respiratory-defective mutant (E264/U2) of Saccharomyces cerevisiae with a yeast genomic library yielded two different plasmids capable of restoring the ability of the mutant to grow on non-fermentable substrates. One of the plasmids (pG52/T3) contained SDH1 coding for the flavoprotein subunit of mitochondrial succinate dehydrogenase. The absence of detectable succinate dehydrogenase activity in mitochondria of E264/U2 and the lack of complementation of the mutant by an sdh11null strain indicated a mutation in SDH1. The second plasmid (pG52/T8) had an insert with reading frame (YJL045w) of yeast chromosome X coding for a homologue of SDH1. Subclones containing the SDH1 homologue (SDH1b), restored respiration in E264/U2 indicating that the protein encoded by this gene is functional. The expression of the two genes was compared by assaying the β-galactosidase activities of yeast transformed with plasmids containing fusions of lacZ to the upstream regions of SDH1 and SDH1b. The 100-500 times lower activity measured in transformants harbouring the SDH1b-lacZ fusion indicates that the isoenzyme encoded by SDH1b is unlikely to play an important role in mitochondrial respiration. This is also supported by the absence of any obvious phenotype in cells with a disrupted copy of SDH1b. © 1998 John Wiley & Sons, Ltd.
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  • 118
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; promoter-substitution cassette ; tetracycline-regulatable promoter ; essential genes ; conditional gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A promoter-substitution cassette has been constructed that allows one-step substitution of chromosomal gene promoters for the tetracycline-regulatable tetO promoter in yeast cells, which uses kanMX4 as selective marker for geneticin resistance. Oligonucleotides for PCR amplification of the cassette are designed to allow homologous recombination through short flanking regions of homology with the upstream sequences of the chromosomal gene, upon transformation of target cells. By testing three essential genes of chromosome XV (YOL135c, YOL142w and YOL144w), the system causes tetracycline-dependent conditional growth of the cells, being modulatable by intermediate concentrations of the effector. Analysis of terminal phenotypes of the promoter-substituted cells in the presence of the antibiotic may facilitate functional analysis of essential orphan genes. © 1998 John Wiley & Sons, Ltd.
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  • 119
    ISSN: 0749-503X
    Keywords: chemostat cultivation ; Saccharomyces cerevisiae ; carbon source ; transcriptional regulation ; UAS ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To identify common regulatory sequences in the promoters of genes, transcription of 31 genes of Saccharomyces cerevisiae was analysed during the transient response to a glucose pulse in a chemostat culture. mRNA levels were monitored during the subsequent excess glucose, ethanol and acetate phases, while other conditions were kept constant. This setup allowed a direct comparison between regulation by glucose, ethanol and acetate.Genes with identical regulation patterns were grouped to identify regulatory elements in the promoters. In respect to regulation on glucose four classes were identified: no transcription under any of the conditions tested, no difference in regulation on glucose, induced on glucose and repressed on glucose. In addition, genes were found that were repressed or induced on ethanol or acetate. Sequence alignment of genes with similar regulation patterns revealed five new, putative regulatory promoter elements. (i) The glucose-inducible fermentation genes PDC1 and ADH1 share the sequence ATACCTTCSTT. (ii) Acetate-repression might be mediated by the decamer CCCGAG RGGA, present in the promoters of ACS2 and ACR1. (iii) A specific element (CCWTTSRNCCG) for the glyoxylate cycle was present in seven genes studied: CIT2, ICL1, MLS1, MDH2, CAT2, ACR1 and ACH1. These genes were derepressed on ethanol or acetate. (iv) The sequence ACGTSCRGAATGA was found in the promoters of the partially ethanol-repressed genes ACS1 and YAT1. (v) Ethanol induction, as seen for ACS2, ADH3 and MDH1, might be mediated via the sequence CGGSGCCGRAG. © 1998 John Wiley & Sons, Ltd.
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  • 120
    ISSN: 0749-503X
    Keywords: LFH deletion cassette ; functional analysis ; chromosome IV ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report here the construction of six deletion mutants and the analysis of their basic phenotype. Deletion cassettes containing the KanMX4 marker module and long flanking regions homologous to the target locus were constructed for each of the six open reading-frames (ORFs YDL088c, YDL087c, YDL086w, YDL085w, YDL084w and YDL082w) located on chromosome IV. Sporulation and tetrad analysis of heterozygous deletant strains revealed that, in the FY1679 genetic background, ORFs YDL088c, YDL087c and YDL084w are essential genes for vegetative growth whereas YDL086w, YDL085w and YDL082w are non-essential. ydl088cΔ and ydl084wΔ haploid strains are viable in the CEN. PK2 genetic background although ydl084wΔ grows at a slower rate than the wild type. Complementation tests by corresponding cognate genes confirmed that gene inactivation was responsible for these growth defects. © 1998 John Wiley & Sons, Ltd.
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  • 121
    ISSN: 0749-503X
    Keywords: Candida boidinii ; peroxisome ; peroxisomal proliferation ; peroxisomal membrane proteins ; d-amino acid oxidase ; green fluorescent protein ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A methylotrophic yeast, Candida boidinii, was grown on various combinations of peroxisome-inducing carbon source(s) (PIC(s)), i.e. methanol, oleate and d-alanine, and the regulation of peroxisomal proteins (both matrix and membrane ones) and organelle proliferation were studied. This regulation was followed (1) at the protein or enzyme level by means of the peroxisomal enzyme activity and Western analysis; (2) at the mRNA level by Northern analysis; and (3) at the organelle level by direct observation of peroxisomes under a fluorescent microscope. Peroxisomal proliferation was followed in vivo by using a C. boidinii strain producing a green fluorescent protein having peroxisomal targeting signal 1. When multiple PICs were used for cell growth, C. boidinii induced specific peroxisomal proteins characteristic of all PIC(s) present in the medium, responding to all PIC(s) simultaneously. Thus, these PICs were considered to induce peroxisomal proliferation independently and not to repress peroxisomes induced by other PICs. Next, the sensitivity of the peroxisomal induction to glucose repression was studied. While the peroxisomal induction by methanol or oleate was completely repressed by glucose, the d-alanine-induced activities of d-amino acid oxidase and catalase, Pmp47, and the organelle proliferation were not. These results indicate that peroxisomal proliferation in yeasts is not necessarily sensitive to glucose repression. Lastly, this regulation was shown to occur at the mRNA level. © 1998 John Wiley & Sons, Ltd.
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  • 122
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; functional genomics ; quantitative phenotype ; chemostat ; competition ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: One possible route to the evaluation of gene function is a quantitative approach based on the concepts of metabolic control analysis (MCA). An important first step in such an analysis is to determine the effect of deleting individual genes on the growth rate (or fitness) of S. cerevisiae. Since the specific growth-rate effects of most genes are likely to be small, we employed competition experiments in chemostat culture to measure the proportion of deletion mutants relative to that of a standard strain by using a quantitative PCR method. In this paper, we show that both densitometry and GeneScan™ analysis can be used with similar accuracy and reproducibility to determine the proportions of (at least) two strains simultaneously, in the range 10-90% of the total cell population. Furthermore, we report on a model competition experiment between two diploid nuclear petite mutants, homozygous for deletions in the cox5a or pet191 genes, and the standard strain (ho::kanMX4/ho::kanMX4) in chemostat cultures under six different physiological conditions. The results indicate that competition experiments in continuous culture are a suitable method to distinguish quantitatively between deletion mutants that qualitatively exhibit the same phenotype. © 1998 John Wiley & Sons, Ltd.
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  • 123
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    Yeast 14 (1998), S. 1437-1438 
    ISSN: 0749-503X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 124
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    Yeast 14 (1998), S. 89-91 
    ISSN: 0749-503X
    Keywords: PCR mutagenesis ; functional domains ; subgenic DNA fragments ; mutagenesis protocol ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Here we describe a method for performing a PCR-driven random mutagenesis of 100 bp DNA fragments that yields mutations at a useful frequency. The method is a modification of the manganese ion substitution PCR technique, and neither creates ‘hot-spots’ nor favors transition mutations over transversions. © 1998 John Wiley & Sons, Ltd.
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  • 125
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    Yeast 14 (1998), S. 67-76 
    ISSN: 0749-503X
    Keywords: cellulose degradation ; endo-β-1,4-glucanase ; cellobiohydrolase ; cellodextrinase ; cellobiase ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Saccharomyces cerevisiae produces several β-1,3-glucanases, but lacks the multicomponent cellulase complexes that hydrolyse the β-1,4-linked glucose polymers present in cellulose-rich biomass as well as in haze-forming glucans in certain wines and beers. We have introduced into S. cerevisiae a functional cellulase complex for efficient cellulose degradation by cloning the Endomyces fibuliger cellobiase (BGL1) gene and co-expressing it with the Butyrivibrio fibrisolvens endo-β-1,4-glucanase (END1), the Phanerochaete chrysosporium cellobiohydrolase (CBH1) and the Ruminococcus flavefaciens cellodextrinase (CEL1) gene constructs in this yeast. The END1, CBH1 and CEL1 genes were inserted into yeast expression/secretion cassettes. Expression of END1, CBH1 and CEL1 was directed by the promoter sequences derived from the alcohol dehydrogenase II (ADH2), the phosphoglycerate kinase I (PKG1) and the alcohol dehydrogenase I (ADH1) genes, respectively. In contrast, BGL1 was expressed under the control of its native promoter. Secretion of End1p and Cel1p was directed by the signal sequence of the yeast mating pheromone α-factor (MFα1), whereas Cbh1p and Bgl1p were secreted using their authentic leader peptides. The construction of a fur1 ura3 S. cerevisiae strain allowed for the autoselection of this multicopy URA3-based plasmid in rich medium. S. cerevisiae transformants secreting biologically active endo-β-1,4-glucanase, cellobiohydrolase, cellodextrinase and cellobiase were able to degrade various substrates including carboxymethylcellulose, hydroxyethylcellulose, laminarin, barley glucan, cellobiose, polypectate, birchwood xylan and methyl-β-d-glucopyranoside. This study could lead to the development of industrial strains of S. cerevisiae capable of converting cellulose in a one-step process into commercially important commodities. © 1998 John Wiley & Sons, Ltd.
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  • 126
    ISSN: 0749-503X
    Keywords: Paracoccidioides brasiliensis ; chitin synthase ; dimorphic fungi ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The nucleotide sequence of a chitin synthase gene (CHS2) of the dimorphic fungal human pathogen Paracoccidioides brasiliensis has been determined. The deduced amino acid sequence of Chs2p consists of 1043 residues and is highly homologous to other class II fungal chitin synthases. Computational structural analyses suggest very high similarity to other fungal chitin synthases with a highly variable region at the cytosolic amino-terminal region which may be related to its possible zymogenic nature, and the putative catalytic region close to seven membrane-spanning regions at the carboxyl terminus. The nucleotide sequence of CHS2 and its flanking regions has been submitted to GenBank under Accession Number Y09231. © 1998 John Wiley & Sons, Ltd.
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  • 127
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    Yeast 14 (1998), S. 189-194 
    ISSN: 0749-503X
    Keywords: branched-chain amino acids ; aminotransferase ; Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Saccharomyces cerevisiae genes for the cytosolic and mitochondrial branched-chain amino-acid aminotransferases (BCAT) were isolated recently. These genes show significant homology to mammalian ECA39, originally isolated as a gene regulated by the c-myc oncogene. We now report the isolation of the Schizosaccharomyces pombe eca39/BCAT gene. The S. pombe protein shows 47-52% identity to other eukaryotic BCAT proteins isolated from S. cerevisiae, nematode, mouse and man. A genetic growth assay for BCAT activity was established using an S. cerevisiae strain disrupted in both BCAT isoenzymes. Consequently, the activity of the S. pombe BCAT was demonstrated by genetic and biochemical means. Possible applications of BCAT-encoding genes as selection markers in yeast transformation are proposed. The sequence has been deposited in the GenBank data library under Accession Number U88029. © 1998 John Wiley & Sons, Ltd.
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  • 128
    ISSN: 0749-503X
    Keywords: recombinant DNA ; K. lactis genomic library ; pCXJ22 ; arginine biosynthesis ; KlARG8 ; mitochondrial transformation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A recombinant plasmid was isolated from a Kluyveromyces lactis genomic DNA library which complements a Saccharomyces cerevisiae arg8 mutant defective in the gene encoding acetylornithine aminotransferase. The complementation activity was found to reside within a 2.0 kb DNA fragment. Nucleotide sequence analysis revealed an open reading frame able to encode a 423-residue protein sharing 68·1% and 35·0% sequence identities with the products of the ARG8 and argD genes of S. cerevisiae and Escherichia coli. That the cloned gene, KlARG8, is the functional equivalent of S. cerevisiae ARG8 was supported by a gene disruption experiment which showed that K. lactis strains carrying a deleted chromosomal copy of KlARG8 are auxotrophic for arginine. The nucleotide sequence of KlARG8 has been submitted to GenBank under Accession Number U93209.
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  • 129
    ISSN: 0749-503X
    Keywords: Escherichia coli ; diacylglycerol kinase ; lipase ; Saccharomyces cerevisiae ; TGL2 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Escherichia coli cells with a disrupted diacylglycerol kinase gene are unable to grow on media containing arbutin due to a lethal accumulation of diacylglycerol. In order to isolate genes from the yeast Saccharomyces cerevisiae involved in diacylglycerol metabolism we complemented an E. coli diacylglycerol kinase disruptant with a yeast genomic library and transformants were selected capable of growing in the presence of arbutin. Using this method, a gene (TGL2) was isolated coding for a protein resembling lipases from Pseudomonas. After expression of the TGL2 gene in E. coli, lipolytic activity towards triacylglycerols and diacylglycerols with short-chain fatty acids could be measured. Therefore, it is very likely that the TGL2 gene can complement the E. coli diacylglycerol kinase disruptant, because it encodes a protein that degrades the diacylglycerol accumulated after growth in the presence of arbutin. Disruption of the TGL2 gene in S. cerevisiae did not result in a detectable phenotype. The role of the Tgl2 protein in lipid degradation in yeast is still unclear. The nucleotide sequence published here has been submitted to the EMBL sequence data bank and is available under accession number X98000. © 1998 John Wiley & Sons, Ltd.
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  • 130
    ISSN: 0749-503X
    Keywords: elongation factor 3 ; YEF3 homolog ; ATPase ; ABC cassette ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Yeast and other fungi contain a soluble elongation factor 3 (EF-3) which is required for growth and protein synthesis. EF-3 contains two ABC cassettes, and binds and hydrolyses ATP. We identified a homolog of the YEF3 gene in the Saccharomyces cerevisiae genome database. This gene, designated YEF3B, is 84% identical in protein sequence to YEF3, which we will now refer to as YEF3A. YEF3B is not expressed during growth under laboratory conditions, and thus cannot rescue growth of YEF3A deletion strains. However, YEF3B can take the place of YEF3A in vivo when expressed from the YEF3A or ADH1 promoters. The products of the YEF3A and YEF3B genes, EF-3A and EF-3B, respectively, were expressed from the ADH1 promoter and purified. Both factors possessed basal and ribosomal-stimulated ATPase activity, and had similar affinity for yeast ribosomes (103 to 113 nm). Km values for ATP were similar, but the Kcat values differed significantly. Ribosome-dependent ATPase activity of EF-3A was more efficient than EF-3B, since the Kcat and Kcat/Km values for EF-3A were about two-fold higher; however, the difference in Kcat/Km values between the two factors was small for basal ATPase activity. © 1998 John Wiley & Sons, Ltd.
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  • 131
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    Yeast 14 (1998), S. 335-345 
    ISSN: 0749-503X
    Keywords: Candida albicans ; arginine permease ; amino acid transport ; affinity chromatography ; functional reconstitution ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have for the first time purified arginine permease from a pathogenic yeast, Candida albicans, to homogeneity by affinity chromatography using L-arginine-linked agarose matrix as affinity column. The purified protein (PP) was of 66 kDa with no subunit structure. Two kinetically distinct binding affinities of PP were evident where high affinity binding (S1) revealed a dependence on acidic pH while pH did not have dramatic effect on low affinity (S2) binding. The specificity of L-arginine binding to PP with regard to other amino acids, structural analogues and inhibitors, was essentially similar to arginine transport observed in the intact cells of C. albicans (Rao et al., 1986). The purified arginine permease was reconstituted into proteoliposomes and its functionality was tested by imposing a valinomycin-induced membrane potential. All the characteristic features of L-arginine transport displayed by the reconstituted system were similar to those observed in intact cells. Thus homogeneous purified arginine permease was also functionally active. © 1998 John Wiley & Sons, Ltd.
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  • 132
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    Yeast 14 (1998), S. 471-477 
    ISSN: 0749-503X
    Keywords: ribosomal protein genes ; yeast genome ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Screening of the complete genome sequence from the yeast Saccharomyces cerevisiae has enabled us to compile a complete list of the genes encoding cytoplasmic ribosomal proteins in this organism.Putative ribosomal protein genes were selected primarily on the basis of the sequence similarity of their products with ribosomal proteins from other eukaryotic organisms, in particular the rat. These genes were subsequently screened for typical yeast rp-gene characteristics, viz. (1) a high codon adaptation index; (2) their promoter structure and (3) their responses to changes in growth conditions.The yeast genome appears to carry 78 different genes, of which 59 are duplicated, encoding 32 different small-subunit and 46 large-subunit proteins. A new nomenclature for these ribosomal proteins is proposed. © 1998 John Wiley & Sons, Ltd.
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  • 133
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    Yeast 14 (1998), S. 401-407 
    ISSN: 0749-503X
    Keywords: yeast ; Kluyveromyces marxianus ; malic acid transport ; mutants ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In malic acid-grown cells of the strains ATCC 10022 and KMS3 of Kluyveromyces marxianus the transport of malic acid occurred by a malate-proton symport, which accepted l-malic, d-malic, succinic and fumaric acids, but not tartaric, malonic or maleic acids. The system was inducible and subjected to glucose repression. Mutants of the strain KMS3, unable to grow in a medium with malic acid, were isolated and checked for their capacity to utilize several carbon sources and to transport dicarboxylic acids by the malate-proton symport. Two distinct clones affected on malate transport were obtained. Both were able to grow on a medium with glycerol or ethanol but not with dl-malic, succinic, oxoglutaric and oxaloacetic acids as the sole carbon and energy sources. However, while one of the mutants (Mal7) displayed activity levels for the enzymes malate dehydrogenase, isocitrate lyase, and phosphoenolpyruvate carboxykinase similar to those of the wild strain, in the other mutant type (Mal6) the activities for the same enzymes were significantly reduced. Plasma membranes from derepressed cells of the wild strain and of the mutants Mal6 and Mal7 were isolated and the protein analysed by SDS-PAGE. The electrophoretic patterns of these preparations differed in a polypeptide with an apparent molecular mass of about 28 kDa, which was absent only in the mutant Mal7. The results indicated that Mal7 can be affected in a gene that encodes a malate carrier in K. marxianus. © 1998 John Wiley & Sons, Ltd.
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  • 134
    ISSN: 0749-503X
    Keywords: gene disruption ; functional analysis ; Saccharomyces cerevisiae ; G418-resistance ; sticky-end PCR ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The disruption of eight novel genes was realized in two genetic backgrounds. Among these open reading frames, NO333, NO348 and NO364 presented homologies with other proteins of yeast or other organisms, whereas NO320, NO325, NO339, NO384 and NO388 showed no similarity with any protein. Tetrad analysis of heterozygous deletant strains revealed that NO348, NO364 and NO388 are essential genes for vegetative growth, whereas NO320, NO325, NO333, NO339 and NO384 are non-essential. Basic phenotypic analyses of the non-lethal deletant strains as suggested in the six-pack B0 programme did not reveal any significant differences between parental and mutant strains. © 1998 John Wiley & Sons, Ltd.
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  • 135
    ISSN: 0749-503X
    Keywords: hexokinase PII ; glycolysis ; Tps1 ; fermentation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the yeast Saccharomyces cerevisiae a novel control exerted by TPS1 (=GGS1=FDP1=BYP1=CIF1=GLC6=TSS1)-encoded trehalose-6-phosphate synthase, is essential for restriction of glucose influx into glycolysis apparently by inhibiting hexokinase activity in vivo. We show that up to 50-fold overexpression of hexokinase does not noticeably affect growth on glucose or fructose in wild-type cells. However, it causes higher levels of glucose-6-phosphate, fructose-6-phosphate and also faster accumulation of fructose-1,6-bisphosphate during the initiation of fermentation. The levels of ATP and Pi correlated inversely with the higher sugar phosphate levels. In the first minutes after glucose addition, the metabolite pattern observed was intermediate between those of the tps1Δ mutant and the wild-type strain. Apparently, during the start-up of fermentation hexokinase is more rate-limiting in the first section of glycolysis than phosphofructokinase. We have developed a method to measure the free intracellular glucose level which is based on the simultaneous addition of d-glucose and an equal concentration of radiolabelled l-glucose. Since the latter is not transported, the free intracellular glucose level can be calculated as the difference between the total d-glucose measured (intracellular+periplasmic/extracellular) and the total l-glucose measured (periplasmic/extracellular). The intracellular glucose level rose in 5 min after addition of 100 mm-glucose to 0·5-2 mm in the wild-type strain, ±10 mm in a hxk1Δ hxk2Δ glk1Δ and 2-3 mm in a tps1Δ strain. In the strains overexpressing hexokinase PII the level of free intracellular glucose was not reduced. Overexpression of hexokinase PII never produced a strong effect on the rate of ethanol production and glucose consumption. Our results show that overexpression of hexokinase does not cause the same phenotype as deletion of Tps1. However, it mimics it transiently during the initiation of fermentation. Afterwards, the Tps1-dependent control system is apparently able to restrict properly up to 50-fold higher hexokinase activity. © 1998 John Wiley & Sons, Ltd.
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  • 136
    ISSN: 0749-503X
    Keywords: sphingolipids ; hydroxylase ; cytochrome b5 ; CSG1 ; CSG2 ; calcium ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Saccharomyces cerevisiae mutants lacking Scs7p fail to accumulate the inositolphosphorylceramide (IPC) species, IPC-C, which is the predominant form found in wild-type cells. Instead scs7 mutants accumulate an IPC-B species believed to be unhydroxylated on the amide-linked C26-fatty acid. Elimination of the SCS7 gene suppresses the Ca2+-sensitive phenotype of csg1 and csg2 mutants. The CSG1 and CSG2 genes are required for mannosylation of IPC-C and accumulation of IPC-C by the csg mutants renders them Ca2+-sensitive. The SCS7 gene encodes a protein that contains both a cytochrome b5-like domain and a domain that resembles the family of cytochrome b5-dependent enzymes that use iron and oxygen to catalyse desaturation or hydroxylation of fatty acids and sterols. Scs7p is therefore likely to be the enzyme that hydroxylates the C26-fatty acid of IPC-C. © 1998 John Wiley & Sons, Ltd.
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  • 137
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    Yeast 14 (1998), S. 359-369 
    ISSN: 0749-503X
    Keywords: SKSI ; snf3 ; low glucose ; over-expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The SKS1 gene was originally identified as a multicopy suppressor of the growth defect of snf3 null mutations on low glucose concentrations. Snf3p is required for the rapid induction of HXT2 during growth on low substrate concentrations. Loss of Snf3p leads to a dramatic delay in expression of HXT2. Adaptation to low substrate concentrations does not occur in snf3 sks1 double null mutant strains, suggesting that SKS1 is required for the glucose-dependent expression of HXT2 in the absence of Snf3p activity. Over-expression of SKS1 leads to over-expression of Hxt2p, thus explaining the mechanism of suppression of the snf3 defect. SKS1 defines a novel, Snf3p-independent pathway for the expression of Hxt2p. Under certain growth conditions, over-expression of SKS1 itself leads to a growth defect which is diminished in snf3 hxt2 double mutants. This suggests that over-expression of Hxt2p at physiologically inappropriate times is detrimental to the cells. © 1998 John Wiley & Sons, Ltd.
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  • 138
    ISSN: 0749-503X
    Keywords: α1-antitrypsin ; Saccharomyces cerevisiae ; Hansenula polymorpha ; Pichia pastoris ; glycosylation ; secretion ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Human α1-antitrypsin (α1-AT) is a major serine protease inhibitor in plasma, secreted as a glycoprotein with a complex type of carbohydrate at three asparagine residues. To study glycosylation of heterologous proteins in yeast, we investigated the glycosylation pattern of the human α1-AT secreted in the baker's yeast Saccharomyces cerevisiae and in the methylotrophic yeasts, Hansenula polymorpha and Pichia pastoris. The partial digestion of the recombinant α1-AT with endoglycosidase H and the expression in the mnn9 deletion mutant of S. cerevisiae showed that the recombinant α1-AT secreted in S. cerevisiae was heterogeneous, consisting of molecules containing core carbohydrates on either two or all three asparagine residues. Besides the core carbohydrates, variable numbers of mannose outer chains were also added to some of the secreted α1-AT. The human α1-AT secreted in both methylotrophic yeasts was also heterogeneous and hypermannosylated as observed in S. cerevisiae, although the overall length of mannose outer chains of α1-AT in the methylotrophic yeasts appeared to be relatively shorter than those of α1-AT in S. cerevisiae. The α1-AT secreted from both methylotrophic yeasts retained its biological activity as an elastase inhibitor comparable to that of α1-AT from S. cerevisiae, suggesting that the different glycosylation profile does not affect the in vitro activity of the protein. © 1998 John Wiley & Sons, Ltd.
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  • 139
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    Yeast 14 (1998), S. 681-686 
    ISSN: 0749-503X
    Keywords: Candida albicans ; cell wall protein ; DNA sequence ; hypha-specific ; proline-rich ; glutamine-rich ; serine and threonine-rich ; HWP1 ; RACE ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A previously isolated partial cDNA encoding a cell wall protein antigen found on hyphal surfaces of the opportunistic fungal pathogen, Candida albicans (Staab et al., 1996) was used to clone the complete hyphal wall protein 1 gene (HWP1). Hyphal forms of C. albicans invade mucosal surfaces of immunocompromised patients such as those with AIDS. HWP1 consisted of an open reading frame predicting an acidic protein (pI of 3·37) with a calculated molecular size of 61,122. The antigenic domain was located in the N-terminal third of the protein. The remainder of the protein contained abundant hydroxy amino acids, and terminated with a string of 15 amino acids typical of sequences specifying post-translational modification with glycosylphosphatidylinositol (6PI). The analyses suggested that Hwp1 is a glucan-linked protein with serine/threonine-rich regions that are predicted to function in extending a ligand-binding domain into the extracellular space. The nucleotide sequence reported in this paper has been submitted to GenBank/EMBL databank with Accession Number U64206. © 1998 John Wiley & Sons, Ltd.
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  • 140
    ISSN: 0749-503X
    Keywords: I-Sce I fragmentation ; yeast ; genome ; cosmids ; colinearity ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The high resolution complete physical maps of chromosomes VII and XV were constructed to form the basis for sequencing these chromosomes as part of the European systematic sequencing programme of the yeast genome, using a unique cosmid library from strain FY1679, and an original top-down mapping strategy involving I-Sce I chromosome fragmentation. A total of 138 and 196 cosmid clones were used to construct the maps for VII and XV, respectively, forming two unique contigs that cover the entirety of chromosomes (1091 kb each), except the telomeric repeats. Colinearity of the cosmid inserts with yeast DNA was verified, and the physical maps were eventually compared with the independently generated genetic maps. © 1998 John Wiley & Sons, Ltd.
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  • 141
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    Yeast 14 (1998), S. 633-646 
    ISSN: 0749-503X
    Keywords: genetic interaction ; membrane traffic ; retrograde transport ; docking complex ; coatomer ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Tip20p is an 80 kDa cytoplasmic protein bound to the cytoplasmic surface of the endoplasmic reticulum (ER) by interaction with the type II integral membrane protein Sec20p. Both proteins are required for vesicular transport between the ER and Golgi complex. Recently, sec20-1 was found to be defective in retrograde transport. A collection of temperature-sensitive tip20 mutants are shown to be lethal in combination with ufe1-1, a target SNARE of the ER and ret2-1, yeast δ-COP. A subset of tip20 mutants was found to be lethal in combination with sec20-1, sec21-1, sec22-3 and sec27-1. Since all pairwise combinations of a tip20 mutant, sec20-1, and ufe1-1 are lethal, Tip20p and Sec20p might be part of the docking complex for Golgi-derived retrograde transport vesicles. Since carboxy-terminal tip20 truncations are lethal in combination with mutants in three coatomer subunits, Tip20p might be involved in binding or uncoating of COPI coated retrograde transport vesicles. © 1998 John Wiley & Sons, Ltd.
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  • 142
    ISSN: 0749-503X
    Keywords: heat shock ; protein-DNA interactions ; transcriptional regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The C-terminal hydrophobic repeat (CTR) of heat shock transcription factor (HSF) has been proposed to regulate DNA binding by intramolecular interactions with the leucine zipper motifs present in the HSF trimerization domain. Schizosaccharomyces pombe provides a useful model organism for the study of the regulation of HSF DNA binding because, unlike Saccharomyces cerevisiae, S. pombe hsf is highly heat shock inducible for DNA binding and contains a clear homology to the CTR. We examined the role that the CTR plays in the regulation of S. pombe hsf by constructing isogenic strains bearing deletion and point mutations in the chromosomal copy of hsf. Surprisingly, we found that point mutation of key hydrophobic amino acids within the CTR, as well as full deletion of it, yielded factors that show normal binding at normal growth temperatures and full levels of heat-induced binding. Deletion of the CTR did, however, slightly lower the temperature required for maximal activation. In contrast, a large deletion of the C-terminus, which removes close to a third of the coding sequence, was deregulated and bound DNA at control temperature. Several of the deletion mutants were significantly reduced in their level of expression, yet they showed wild-type levels of DNA binding activity following heat shock. These experiments demonstrate that appropriate regulation of the DNA binding activity of S. pombe hsf is not solely dependent upon the CTR, and imply that a feedback mechanism exists that establishes proper levels of DNA binding following heat shock despite mutations that significantly alter levels of total hsf. © 1998 John Wiley & Sons, Ltd.
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  • 143
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    Yeast 14 (1998), S. 747-757 
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; ubiquitin carrier proteins ; cyclin degradation ; functional analysis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: UBC11 is the Saccharomyces cerevisiae gene that is most similar in sequence to E2-C, a ubiquitin carrier protein required for the destruction of mitotic cyclins and proteins that maintain sister chromatid cohesion in animal cells and in Schizosaccharomyces pombe. We have disrupted the UBC11 gene and found it is not essential for yeast cell viability even when combined with deletion of UBC4, a gene that has also been implicated in mitotic cyclin destruction. Ubc11p does not ubiquitinate cyclin B in clam cell-free extracts in vitro and the destruction of Clb2p is not impaired in extracts prepared from Δubc11 or Δubc4Δubc11 cells. These results suggest Ubc4p and Ubc11p together are not essential for mitotic cyclin destruction in S. cerevisiae and we can find no evidence to suggest that Ubc11p is the true functional homologue of E2-C. © 1998 John Wiley & Sons, Ltd.
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  • 144
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    Yeast 14 (1998), S. 773-781 
    ISSN: 0749-503X
    Keywords: dolichol-PP-GlcNAc2 ; translocation ; endoplasmic reticulum ; alg1 ; exoglucanase ; S. cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Transfer of truncated oligosaccharides to yeast exoglucanase (Exg) in Saccharomyces cerevisiae alg1 has been investigated. When incubated at the non-permissive temperature, alg1 cells secreted into the culture medium, in addition to the exoglucanase glycoforms secreted by wild type, underglycosylated forms as well as material with ionic properties of the non-glycosylated enzyme. As expected, none of the latter had affinity towards concanavalin A, but part of it bound to wheat germ agglutinin (WGA), suggesting that it contained, in addition to non-glycosylated Exg, glycoforms carrying non-reducing terminal GlcNAc. Only the WGA-bound material could be labelled with galactosyltransferase; furthermore, the label could be released by treatment with peptide-N4-N-acetyl-β-glucosamine asparagine amidase. These results unambiguously demonstrate that GlcNAc2 can be transferred from dolichol-PP-GlcNAc2 to one or both sequons of yeast Exg. Accordingly, they support previous observations suggesting that this early intermediate is able to translocate in vivo in order to make its sugar portion accessible to the oligosaccharyltransferase in the lumen of the endoplasmic reticulum. © 1998 John Wiley & Sons, Ltd.
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  • 145
    ISSN: 0749-503X
    Keywords: esterase ; beer ; brewer's yeast ; enzymatic hydrolysis ; specificity ; Saccharomyces cerevisiae TIP1 gene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An extracellular esterase was isolated from the brewer's yeast, Saccharomyces carlsbergensis. Inhibition by diisopropyl fluorophosphate shows that the enzyme has a serine active site. By mass spectrometry, the molecular weight of the enzyme was 16·9 kDa. The optimal pH for activity was in the range of four to five. Esterase activity was found in beer before pasteurization, and a low level of activity was still present after pasteurization. Caprylic acid, which is present in beer, competitively inhibited the esterase. The substrate preference towards esters of p-nitrophenol indicated that the enzyme prefers esters of fatty acids from four to 16 carbon atoms. The esterase has lipolytical activity; olive oil (C-18:1), which is a classical substrate for lipase, was hydrolysed. N-terminal sequence analysis of the esterase yielded a sequence which was identical to the deduced amino acid sequence of the S. cerevisiae TIP1 gene. The esterase preparation did not appear to contain significant amounts of other proteins than Tip1p, indicating that the TIP1 gene is the structural gene for the esterase. © 1998 John Wiley & Sons, Ltd.
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  • 146
    ISSN: 0749-503X
    Keywords: fermentation ; β-galactosidase ; heterologous gene expression ; Kluyveromyces lactis ; lactose-permease ; ribosomal DNA ; whey ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A diploid strain of Saccharomyces cerevisiae able to metabolize lactose with high efficiency has been obtained. Haploid strains of Saccharomyces able to grow on lactose were constructed by cotransformation with two genes of Kluyveromyces lactis required for the utilization of the sugar, LAC4 and LAC12, encoding β-galactosidase and lactose permease respectively. Both genes were placed under the control of a galactose-inducible promoter and targeted to the rDNA encoding region (RDN1 locus) of the Saccharomyces genome. Lac+ transformants were selected on medium with lactose as the only carbon source. These transformants were mitotically stable, they maintained the Lac+ phenotype after growing in non-selective medium for more than 60 generations, but their growth was slow. We found that this lack of vigour was caused by their genetic background and not by a deficient expression of the heterologous genes. Therefore, their performance could be improved by crossing with a wild-type strain. Among the offspring of the crosses, two strains of opposite mating type were selected and mated to obtain a fast-growing Lac+ diploid. This diploid strain showed the typical fermentative behaviour of S. cerevisiae when it was grown in aerated liquid medium with glucose. In lactose medium, it exhibited a respiro-fermentative metabolism similar to that of K. lactis, with low ethanol production and high biomass yield. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 7 Ill.
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  • 147
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 895-903 
    ISSN: 0749-503X
    Keywords: Pichia pastoris ; pulsed-field gel electrophoresis ; chromosome-length polymorphisms ; gene stability ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have clearly resolved four chromosomal bands from four Pichia pastoris (Komagataella pastoris) strains by using contour-clamped homogeneous electric field gel electrophoresis. The size of the P. pastoris chromosomal bands ranged from 1·7 Mb to 3·5 Mb and total genome size was estimated to be 9·5 Mb to 9·8 Mb; however, chromosome-length polymorphisms existed among four strains. Thirteen cloned genes isolated from strain GTS115 were assigned to the separated chromosomes, revealing that different hybridization patterns were observed in the AOX2 and URA3 genes among strains. P. pastoris is frequently used as an efficient host for heterologous gene expressions. We analysed chromosomal stability of strain GTS115-derived recombinant cell expressing human serum albumin during serial cultivation under the condition of vegetative and non-selective growth. No chromosomal rearrangements were observed and the expression constructs integrated into the his4 locus on chromosome I were very stable even at 83 generations, suggesting that stable expression would be carried out even in large-scale fermentation. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 148
    ISSN: 0749-503X
    Keywords: epitope tagging ; green fluorescent protein ; functional analysis ; overexpression studies ; gene deletion ; gene truncation ; polymerase chain reaction ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An important recent advance in the functional analysis of Saccharomyces cerevisiae genes is the development of the one-step PCR-mediated technique for deletion and modification of chromosomal genes. This method allows very rapid gene manipulations without requiring plasmid clones of the gene of interest. We describe here a new set of plasmids that serve as templates for the PCR synthesis of fragments that allow a variety of gene modifications. Using as selectable marker the S. cerevisiae TRP1 gene or modules containing the heterologous Schizosaccharomyces pombe his5+ or Escherichia coli kanr gene, these plasmids allow gene deletion, gene overexpression (using the regulatable GAL1 promoter), C- or N-terminal protein tagging [with GFP(S65T), GST, or the 3HA or 13Myc epitope], and partial N- or C-terminal deletions (with or without concomitant protein tagging). Because of the modular nature of the plasmids, they allow efficient and economical use of a small number of PCR primers for a wide variety of gene manipulations. Thus, these plasmids should further facilitate the rapid analysis of gene function in S. cerevisiae. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
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  • 149
    ISSN: 0749-503X
    Keywords: alcohol acetyltransferase ; ATF1 gene ; OLE1 gene ; unsaturated fatty acid ; oxygen ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ATF1 gene encodes an alcohol acetyl transferase which catalyzes the synthesis of acetate esters from acetyl CoA and several kinds of alcohols. ATF1 expression is repressed by unsaturated fatty acids or oxygen. Analysis using ATF1-lacZ fusion plasmid revealed that ATF1 gene expression is widely repressed by a variety of unsaturated fatty acids, and the degree of ATF1 transcriptional repression varies according to the structure of the unsaturated fatty acids. Interestingly, it was noted that the degree of ATF1 transcriptional repression was related to the melting point of unsaturated fatty acids added to the medium. The OLE1 gene, which encodes Δ-9 fatty acid desaturase, has been reported to be repressed by unsaturated fatty acids. Transcription of OLE1 was also repressed by a wide variety of unsaturated fatty acids under anaerobic conditions. The degree of transcriptional repression of OLE1 was also related to the melting point of the added unsaturated fatty acids. Therefore, it is considered that ATF1 and OLE1 transcription are regulated in response to cell membrane fluidity. As has been reported for OLE1, the repression of ATF1 by unsaturated fatty acids was relieved in a disruptant carrying a faa1 and faa4 double mutation, two fatty acid activation genes. However, the ATF1 transcript in this double gene disruptant was repressed by oxygen. These results suggested that ATF1 transcription was co-regulated by the same mechanism as the OLE1 gene and that unsaturated fatty acids and oxygen repressed the ATF1 transcript by a different regulation pathway. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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  • 150
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; gene cloning ; gene disruption ; functional analysis ; chromosome XVI ; translation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A 7·24 kb genomic DNA fragment from the yeast Saccharomyces cerevisiae chromosome XVI was isolated by complementation of a new temperature-sensitive mutation tsa1. We determined the nucleotide sequence of this fragment located on the right arm of chromosome XVI. Among the three, complete open reading frames: YPR041w, YPR042c and YPR043w contained within this fragment, the gene YPR041w was shown to complement the tsa1 mutation and to correspond to the TIF5 gene encoding an essential protein synthesis initiation translation factor. The YPR042c gene encodes a hypothetical protein of 1075 amino acids containing four putative transmembrane segments and is non-essential for growth. The gene YPR043c encoding the 10 kDa product, highly similar to the human protein L37a from the 60S ribosomal subunit, was found to be essential and a dominant lethal. We conclude that three tightly linked yeast genes are involved in the translation process. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
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  • 151
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 1007-1016 
    ISSN: 0749-503X
    Keywords: nicotine ; diphenylamine ; astaxanthin biosynthesis ; Xanthophyllomyces dendrorhous ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effect of nicotine and diphenylamine on astaxanthin biosynthesis in Xanthophyllomyces dendrorhous was studied. The effects were analysed under standard and low temperature conditions. It was found that 10 mm-nicotine inhibits the cyclization of lycopene and de novo protein synthesis was not needed to reverse the inhibition. The oxidation of β-carotene was irreversibly inhibited by 10 μM-diphenylamine while the dehydrogenation of phytoene was reversibly inhibited by 60 μM-diphenylamine. The simultaneous exposure to low temperature (4°C) overcomes the inhibition of β-carotene oxidation at low diphenylamine concentration. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
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  • 152
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 1471-1510 
    ISSN: 0749-503X
    Keywords: yeast ; S. cerevisiae ; lipids ; phospholipids ; sterols ; sphingolipids ; fatty acids ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The yeast Saccharomyces cerevisiae is a powerful experimental system to study biochemical, cell biological and molecular biological aspects of lipid synthesis. Most but not all genes encoding enzymes involved in fatty acid, phospholipid, sterol or sphingolipid biosynthesis of this unicellular eukaryote have been cloned, and many gene products have been functionally characterized. Less information is available about genes and gene products governing the transport of lipids between organelles and within membranes, turnover and degradation of complex lipids, regulation of lipid biosynthesis, and linkage of lipid metabolism to other cellular processes. Here we summarize current knowledge about lipid biosynthetic pathways in S. cerevisiae and describe the characteristic features of the gene products involved. We focus on recent discoveries in these fields and address questions on the regulation of lipid synthesis, subcellular localization of lipid biosynthetic steps, cross-talk between organelles during lipid synthesis and subcellular distribution of lipids. Finally, we discuss distinct functions of certain key lipids and their possible roles in cellular processes. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 153
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    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 935-942 
    ISSN: 0749-503X
    Keywords: antifungal drugs ; cytochrome-c oxidase ; gene dosage screening ; lanosterol C-14 demethylase ; overexpression assay ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The post-genome sequencing era of Saccharomyces cerevisiae is defined by the analysis of newly discovered open reading frames of unknown function. In this report, we describe a genetic method for the rapid identification and characterisation of genes involved in a given phenotype. This approach is based on the ability of overexpressed genomic DNA fragments to cure an induced phenotype in yeast. To validate this concept, yeast cells carrying a yeast DNA library present on multicopy plasmid vectors were screened for resistance to the antifungal drug ketoconazole. Among 1·2 million colonies 13 clones tested positive, including those expressing the lanosterol C-14 demethylase, known to be a cellular target for azole drugs, and the cytochrome-c oxidase of mitochondria, regulating the respiratory chain electron transport. Several other resistant clones were identified, which code for yeast proteins of so far unknown function. These genes may represent potential candidates for antifungal drug effects. Together with the availability of the entire yeast genome sequence, the described genetic screening method is a powerful tool for the effective functional analysis of yeast genes. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
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