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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 197 (2001), S. 0 
    ISSN: 1574-6968
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The Escherichia coli transcriptional regulatory complex FlhD/FlhC, initially identified as a flagella-specific activator, is a global regulator involved in many cellular processes. Using gene arrays, lacZ gene fusions and enzyme assays, eight new targets of FlhD/FlhC were recognized. These are the transporter for galactose (MglBAC), the rod-shape determination proteins (MreBCD), malate dehydrogenase, and several enzymes involved in anaerobic respiration (glycerol 3-phosphate dehydrogenase, GlpABC; periplasmic nitrate reductase, NapFAGHBC; nitrite reductase, NrfABCDEFG; dimethyl sulfoxide reductase, DmsABC; and the modulator for hydrogenases, HydNHypF).
    Materialart: Digitale Medien
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  • 2
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: We used DNA macroarray analysis to identify genes that respond to the status of the intracellular acetyl phosphate (acP) pool. Genes whose expression correlated negatively with the ability to synthesize acP (i.e. negatively regulated genes) function primarily in flagella biosynthesis, a result consistent with observations that we published previously (Prüß and Wolfe, 1994, Mol Microbiol 12: 973–984). In contrast, genes whose expression correlated positively with the ability to synthesize acP (i.e. positively regulated genes) include those for type 1 pilus assembly, colanic acid (capsule) biosynthesis and certain stress effectors. To our knowledge, this constitutes the first report that these genes may respond to the status of the intracellular acP pool. Previously, other researchers have implicated flagella, type 1 pili, capsule and diverse stress effectors in the formation of biofilms. We therefore tested whether cells altered in their ability to metabolize acP could construct normal biofilms, and found that they could not. Cells defective for the production of acP and cells defective for the degradation of acP could both form biofilms, but these biofilms exhibited characteristics substantially different from each other and from biofilms formed by their wild-type parent. We confirmed the role of individual cell surface structures, the expression of which appears to correlate with acP levels, in fim or fli mutants that cannot assemble type 1 pili or flagella respectively. Thus, the information gained by expression profiling of cells with altered acP metabolism indicates that acP may help to co-ordinate the expression of surface structures and cellular processes involved in the initial stages of wild-type biofilm development.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Many species of bacteria devote considerable metabolic resources and genetic information to the ability to sense the environment and move towards or away from specific stimuli using flagella. In Escherichia coli and related species, motility is regulated by several global regulatory circuits, which converge to modulate the overall expression of the master operon for flagellum biosynthesis, flhDC. We now show that the global regulator CsrA of E. coli K-12 is necessary for motility under a variety of growth conditions, as a result of its role as an activator of flhDC expression. A chromosomally encoded flhDC′–′lacZ translational fusion was expressed at three- to fourfold higher levels in csrA wild-type strains than in isogenic csrA mutants. Purified recombinant CsrA protein stimulated the coupled transcription-translation of flhDC′–′ lacZ in S-30 extracts and bound to the 5′ segment of flhDC mRNA in RNA mobility shift assays. The steady-state level of flhDC mRNA was higher and its half-life was ≈ threefold greater in a csrA wild-type versus a csrA mutant strain. Thus, CsrA stimulates flhDC gene expression by a post-transcriptional mechanism reminiscent of its function in the repression of glycogen biosynthesis.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-072X
    Schlagwort(e): Archaebacteria ; Haloarcula vallismortis ; Glyceraldehyde 3-phosphate dehydrogenase ; Halophilism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.12) from the extremely halophilic archaebacterium Haloarcula vallismortis has been purified in a four step procedure to electrophoretic homogeneity. The enzyme is a tetramer with a relative molecular mass of 160000. It is strictly NAD+-dependent and exhibits its highest activity in 2 mol/l KCl at 45°C. Amino acid analysis and isoelectric focusing indicate an excess of acidic amino acids. Two parts of the primary sequence are reported. These peptides have been compared with glyceraldehyde 3-phosphate dehydrogenases from other archaebacteria, eubacteria and eucaryotes. The peptides show a high grade of similarity to glyceraldehyde 3-phosphate dehydrogenase from eucaryotes.
    Materialart: Digitale Medien
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