Involvement of lipopolysaccharide in the secretion of Escherichia coli alpha-haemolysin and Erwinia chrysanthemi proteases.
The presence of the alpha-haemolysin secretion genes sensitizes Escherichia coli to vancomycin, a glycopeptide antibiotic that is normally excluded from the Gram-negative envelope (owing to its large size) (M(r) 1400). The selection of vancomycin mutants in strains carrying such genes was found to be a very powerful method for selecting non-haemolytic mutants. In this way, mutations in the known secretion genes, hlyB, hlyD and tolC, were obtained. However additional mutations mapped in genes rfaH and galU which are required for lipopolysaccharide (LPS) biosynthesis. Mutations in rfaH and galU strongly reduced alpha-haemolysin secretion as well as the secretion of Erwinia chrysanthemi proteases in E. coli without affecting their synthesis. These mutations markedly lowered the content of TolC protein, required for haemolysin secretion and also of the PrtF protein necessary for protease secretion. These results raise the possibility that LPS is involved in the correct incorporation of the TolC and PrtF proteins into the cell envelope.
Wandersman
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Unité de Génétique Moléculaire, CNRS UA 1149, Institut Pasteur, Paris, France.
Létoffé
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D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D016974:Dickeya chrysanthemi / Q000201:enzymology / Q000502:physiology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D010450:Endopeptidases / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006460:Hemolysin Proteins; D008070:Lipopolysaccharides / Q000378:metabolism*; D026901:Membrane Transport Proteins; D009154:Mutation; D010957:Plasmids; D015533:Transcriptional Activation; D014640:Vancomycin / Q000494:pharmacology
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D008070:Lipopolysaccharides; D026901:Membrane Transport Proteins; C073126:tolC protein, E coli; D014640:Vancomycin; D010450:Endopeptidases