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  • 1
    Electronic Resource
    Electronic Resource
    Intracistronic transcription termination in polysialyltransferase gene (siaD ) affects phase variation in Neisseria meningitidis (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 33 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Expression of serogroup B meningococcal capsular polysaccharide is subject to frequent phase variation. A reversible +1/−1 frameshift mutation within a poly(dC) repeat altering the reading frame of the polysialyltransferase gene (siaD ), thereby causing premature arrest of translation, is responsible for loss of capsule expression. After analysis of transcription of the siaD gene from an encapsulated strain and from two unencapsulated derivatives, we have found that the siaD mRNA in the unencapsulated strains is reduced in size as a result of premature transcription termination at a cryptic Rho-dependent site within the proximal region of the siaD cistron. Termination is sensitive to bicyclomycin, a natural inhibitor of Rho activity. Bicyclomycin decreased the rates of capsule re-expression (off–on) without affecting the rates of loss of capsule expression (on–off). This finding suggested the existence of a novel mechanism linking transcription elongation termination and mutation frequency. A genetic system was therefore developed to measure phase variation of siaD–ermC′ gene fusions in wild type and Rho-defective Escherichia coli strains. These studies demonstrated that in the Rho-defective E. coli strain readthrough transcription of the mutated siaD gene caused a fourfold lower off–on phase variation rate than in the congenic Rho+ strain. Analysis of phase variation of siaD–ermC′ gene fusions in a DNA mismatch-defective E. coli strain suggests that the effect of transcription on mutation rates required a functional mismatch repair system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01454.x
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  • 2
    Electronic Resource
    Electronic Resource
    Regulation and differential expression of gdhA encoding NADP-specific glutamate dehydrogenase in Neisseria meningitidis clinical isolates (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Meningococcal gdhA, encoding the NADP-specific l-glutamate dehydrogenase (NADP-GDH), is essential for systemic infection in an infant rat model. In this paper, a limited transcriptional analysis detected differences in gdhA expression among clinical isolates. In strains expressing high levels of gdhA mRNA, two promoters, gdhA P1 and gdhA P2, initiated transcription of gdhA. In contrast, in strains expressing low mRNA levels, gdhA P2 was not active because of weak expression of gdhR, an associated regulatory gene. Gene knock-out and complementation of a gdhR-defective mutant confirmed that GdhR is a positive regulator for gdhA P2. Trans-activation of gdhA P2 was maximal in complex medium during late logarithmic growth phase and in chemical defined medium (MCDA) when glucose (MCDA-glucose) instead of lactate (MCDA-lactate) was used as a carbon source in the presence of glutamate. gdhR knock-out mutants lost both growth phase and carbon source regulation, and exhibited a growth defect more severe in MCDA-glucose than in MCDA-lactate. DNA–protein interaction studies demonstrated that 2-oxoglutarate, a product of the catabolic reaction of the NADP-GDH and an intermediate of the tricarboxylic acid (TCA) cycle, inhibits binding of GdhR to gdhA P2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2003.03947.x
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  • 3
    Electronic Resource
    Electronic Resource
    Type III a glycogenosis (1967)
    Springer
    Virchows Archiv 343 (1967), S. 164-176 
    Details
    ISSN: 1432-2307
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A combined biochemical and ultrastructural study, including cytochemical and negative staining techniques, has been made of three tissues, liver, muscle and leucocytes, in a case of type III A glycogenosis. The electron microscopic studies revealed an increased accumulation of glycogen in the liver, in the skeletal muscle and in the leucocytes. The hepatic glycogen, either isolated or within the hepatocytes, is mostly represented in the form of monoparticulate granules and of rosettes with fewer component units, whereas the typical rosettes are rare. The isolated and intracellular glycogen of muscle cells appears composed of monoparticulate granules, as in normal muscle cells. The biochemical studies confirm the diagnosis of type III A glycogenosis and seem to exclude the simultaneous occurrence of the enzymatic defect responsible for type II glycogenosis.
    Notes: Zusammenfassung Die Beobachtung einer Glykogenose (Typus III A) bei einem 11 Jahre alten Jungen wurde biochemisch, elektronenmikroskopisch, cytotopochemisch und durch eine Reihe sog. Negativfärbungen durchgearbeitet. In Leber, Muskulatur und Leukocyten wurden starke Glykogenanhäufungen nachgewiesen. Das Leberglykogen war, sowohl in Schnittpräparaten als auch bei isolierter Untersuchung, von dem normalen Glykogen des gesunden Menschen deutlich verschieden. Sogenannte typische Rosetten wurden nur ganz ausnahmsweise gefunden. Dagegen fanden sich sog. kleine Rosetten, jeweils zusammengesetzt aus einigen wenigen Partikeln, vor allem aber monopartikuläre Granula. In der Muskulatur jedoch trat das Glykogen, wie auch beim gesunden Menschen, monopartikulär und granuliert auf.Biochemisch konnte die Diagnose einer Glykogenose des Typus III A eindeutig gestellt werden. Es haben sich keine Anzeichen dafür nachweisen lassen, daß ein sog. Fermentdefekt, etwa wie bei einer Glykogenose des Typus II, zugrunde lag.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01429736
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation of a cDNA clone encoding rat insulin-like growth factor-II precursor (1984)
    [s.l.] : Nature Publishing Group
    Nature 312 (1984), S. 277-280 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A cDNA library was constructed from 12S poly(A)+ mRNA from BRL-3A cells (see Fig. 1 legend) and screened using a 5'[y-32P]-labelled tetradecamer (designated 14-mer A) corresponding to amino acids 44-48 of rat IGF-II11. Twenty out of -10,000 transformants screened at high cell density gave a strong ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/312277a0
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  • 5
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of the Escherichia coli hisD gene and of the Escherichia coli and Salmonella typhimurium hisIE region (1986)
    Springer
    Molecular genetics and genomics 203 (1986), S. 382-388 
    Details
    ISSN: 1617-4623
    Keywords: DNA ; Operons ; Codon usage ; Bifunctional enzymes ; Homology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this paper we report the nucleotide sequence of the hisD gene of Escherichia coli and of the hisIE region of both E. coli and Salmonella typhimurium. The hisD gene codes for a bifunctional enzyme, l-histidinol: NAD+ oxidoreductase, of 434 amino acids with a molecular mass of 46,199 daltons. We established that the hisIE region of both S. typhimurium and E. coli is composed of a single gene and not, as previously believed, of two separate genes. The derived amino acid sequence indicates that the hisIE gene codes for a bifunctional protein of 203 amino acids with an approximate molecular mass of 22,700 daltons. We also determined the nucleotide sequence of a deletion mutant in S. typhimurium which abolishes the hisF and hisI functions but retains the hisE function. We deduced that the mutant produces a chimeric protein fusing the aminoterminal region of the upstream hisF gene to the carboxylterminal domain of the hisIE gene which encodes for the hisE function. In view of these results the structural and functional organization of the histidine operon in enteric bacteria needs to be revised. The operon is composed of only 8 genes and the pathway leading to the biosynthesis of the amino acid requires 11 enzymatic steps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422061
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  • 6
    Electronic Resource
    Electronic Resource
    Primary and secondary structural homologies between the HIS4 gene product of Saccharomyces cerevisiae and the hisIE and hisD gene products of Escherichia coli and Salmonella typhimurium (1986)
    Springer
    Molecular genetics and genomics 203 (1986), S. 389-396 
    Details
    ISSN: 1617-4623
    Keywords: Histidinol dehydrogenase ; Hydropathy ; Translation ; Gene fusion ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A detailed comparative analysis of the Escherichia coli and Salmonella typhimurium hisIE and hisD gene products and the functionally equivalent, single, HIS4 gene product of Saccharomyces cerevisiae permitted several insights concerning the relationship between these genes. Our analysis supports the idea that HIS4 results from the fusion of hisIE and hisD. The comparison permitted a more precise definition of the functional domains of hisI/HIS4A and hisE/HIS4B as well as the two functional domains of hisD/HIS4C. The homologies between the bacterial and yeast sequences suggest a region of the hisD/HIS4C protein that may constitute one of the active centres. A large fragment at the amino terminal region of the yeast protein is missing from the bacterial hisIE gene product and is probably not needed for catalytic activity. Another region of non-homology in the yeast protein is probably a peptide bridge connecting the HIS4AB domain to HIS4C. Although the overall homology at the level of amino acid sequence is modest (about 38%) there is a striking similarity when the hydropathic patterns and predicted secondary structural configurations of these proteins are compared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422062
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  • 7
    Electronic Resource
    Electronic Resource
    Genetic mapping of the mouse Rab7 gene and pseudogene and of the human RAB7 homolog (1998)
    Springer
    Mammalian genome 9 (1998), S. 448-452 
    Details
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Rab proteins are small GTP-ases localized to distinct membrane compartments in eukaryotic cells and regulating specific steps of intracellular vesicular membrane traffic. The Rab7 protein is localized to the late endosomal compartment and controls late steps of endocytosis. We have isolated, by library screening, the 5′ region, including the promoter, of the mouse Rab7 gene and a Rab7 pseudogene. We have mapped, by genetic linkage analysis, the mouse Rab7 gene on Chromosome (Chr) 6 and the Rab7-ps1 pseudogene on Chr 9, where the Rab7 gene has been previously reported to map. By radiation hybrid mapping, we have located the human RAB7 gene on Chr 3, in a region homologous to the mouse Chr 6, where the Rab7 gene maps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003359900794
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  • 8
    Electronic Resource
    Electronic Resource
    DNA synthesis in cultured human fibroblasts: Regulation by 3′ : 5′-cyclic amp (1976)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 4 (1976), S. 199-204 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The addition of serum to density-inhibited human fibroblast cultures induced a wave of DNA synthesis, measured as [3H] thymidine incorporation into acid-precipitable material, beginning after 8-12 hr and reaching maximum levels at 16-24 hr. Addition of dibutyryl-3′ : 5′-cyclic AMP (DBcAMP) together with serum inhibited [3H] thymidine incorporation by 75-95%. When DBcAMP was added for the first 4 hr of serum stimulation and then removed, the wave of DNA synthesis was not delayed. This suggested that serum could induce DNA synthesis even though cyclic AMP concentrations were maintained at high levels by DBcAMP during this initial period. These results are inconsistent with the hypothesis that it is the immediate transient reduction in 3′ : 5′-cyclic AMP concentration following the addition of serum that triggers DNA synthesis. By contrast, DBcAMP added 8 hr after serum inhibited [3H] thymidine incorporation to the same extent as DBcAMP added at the same time as serum. This indicated that a step essential for DNA synthesis and occurring late in G1 was inhibited by high concentrations of 3′ : 5′-cyclic AMP.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400040207
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