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  • 1
    Electronic Resource
    Electronic Resource
    Isolation and analysis of functional homologues of the secretion-related SAR1 gene of Saccharomyces cerevisiae from Aspergillus niger and Trichoderma reesei (1997)
    Springer
    Molecular genetics and genomics 256 (1997), S. 446-455 
    Details
    ISSN: 1617-4623
    Keywords: Key words Gene cloning ; Protein secretion ; Filamentous fungi ; Small GTP binding protein ; Complementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Aspergillusniger and Trichodermareesei genes encoding the functional homologues of the small GTP-binding protein SAR1p, which is involved in the secretion pathway in Saccharomyces cerevisiae, have been cloned and characterised. The A. niger gene (sarA) contains five introns, whereas the T. reesei gene (sar1) has only four. In both cases the first intron is at the same position as the single S. cerevisiae SAR1 intron. The encoded proteins show 70–80% identity to the SAR1 protein. Complementation of S. cerevisiaesar1 and sec12 mutants by expression vectors carrying the A. nigersarA and T. reesei sar1 cDNA clones confirmed that the cloned genes are functional homologues of the S. cerevisiae SAR1 gene. Three mutant alleles of the A. nigersarA gene (D29G, E109K, D29G/E109K), generated by site-directed mutagenesis, revealed a thermosensitive dominant-negative phenotype in the presence of the wild-type sarA allele. This result contrasts with the situation in S. cerevisiae, where similar mutations have a thermosensitive phenotype. Taken together, our results indicate that the sarA gene is involved in an essential function in A. niger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008613
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  • 2
    Electronic Resource
    Electronic Resource
    Regulation of expression of the Aspergillus niger benzoate para-hydroxylase cytochrome P450 system (2000)
    Springer
    Molecular genetics and genomics 263 (2000), S. 601-609 
    Details
    ISSN: 1617-4623
    Keywords: Key words Cytochrome P450 ; Post-transcriptional regulation ; Benzoate ; Aspergillus niger
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytochrome P450 enzyme systems are found throughout nature and are involved in many different, often complex, bioconversions. In the endoplasmic reticulum of the filamentous fungus Aspergillus niger a cytochrome P450 enzyme system is present that is capable of the para-hydroxylation of benzoate. The expression of the two genes encoding the components of this system, the cytochrome P450 gene encoding benzoate para-hydroxylase (bphA) and the gene encoding cytochrome P450 reductase (cprA), is inducible by benzoate. The BPH system was used as a model system to study the mechanisms that result in co-regulation of both components of an eukaryote cytochrome P450 enzyme system. Deletion analysis of the transcription control regions of cprA and bphA resulted in the identification of a region that was involved in benzoate induction of gene expression. The functional competence of the cprA Benzoate Responsive Region thus defined was demonstrated directly by cloning this fragment upstream of a constitutively expressed mini-promoter and analysing expression of the hybrid transcription control region in a lacZ reporter system. Further analysis of cprA gene expression revealed a clear quantitative discrepancy between induction at the protein level (approximately 4-fold) and at the transcription level (〉20-fold). The majority of the transcripts observed after benzoate induction (cprAβ) were larger then the constitutively expressed cprAα transcript. The difference in size between the cprAα and cprAβ transcript is caused by differential promoter use. As the longer cprAβ transcript carries a small uORF we propose that post-transcriptional regulation of CPR expression underlies the discrepancy in the degree of induction at the protein and transcriptional level. Our results show that regulation of CPR expression is particularly complex, involving regulatory promoter elements, differential promoter use and regulation at the post-transcriptional level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380051207
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    Paper (German National Licenses)
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