View source for Molecular Microbiology (1996) 24, 555-566

{{Publication
|Publication authors=C.E. Barber, J.L. Tang, J.X. Feng, M.Q. Pan, T.J.G. Wilson, H. Slater, J.M. Dow, P. Williams and M.J. Daniels
|Author Page=J. Maxwell Dow
|Publication date=1996
|dc:title=A novel regulatory system required for pathogenicity of ''Xanthomonas campestris'' is mediated by a small diffusible signal molecule
|Publication journal=Molecular Microbiology
|prism:volume=24 (3)
|prism:startingPage=555
|Last page=566
|DOI=10.1046/j.1365-2958.1997.3721736.x
|Publication abstract=Mutations in the seven clustered ''rpf'' genes cause downregulated synthesis of extracellular enzymes and reduced virulence of ''Xanthomonas campestris'' pathovar ''campestris'' (''Xcc''). The phenotype of mutants in one of the genes, ''rpfF'', can be restored by a diffusible extracellular factor (DSF) produced by all ''Xcc'' strains tested, apart from ''rpfF'' and ''rpfB'' mutants. DSF accumulates in early stationary phase (when synthesis of enzymes is maximal), but levels decline subsequently. Addition of DSF to exponentially-growing wild-type bacteria does not cause precocious enzyme synthesis. ''rpfB'' and ''rpfF'' are expressed throughout growth, but the rate increases in early stationary phase. RpfB is predicted to be a long-chain fatty acyl CoA ligase, and RpfF shows some relatedness to enoyl CoA hydratases. The properties of DSF suggest that it may be a fatty-acid derivative, and certain lipid preparations possess DSF activity at higher concentrations. These include lipid extracts and acid-hydrolysed lipopolysaccharide and lipid A from ''Xcc'', and purified dodecanoic and hydroxydodecanoic acid. DSF production is confined to certain xanthomonads. We propose a model for the DSF system, which represents a novel mechanism for regulating virulence factor synthesis in response to physiological or environmental changes.
|AbstractCC=Yes
|Research topic=molecular biology - genes
|Is book=No
}}
{{Pest record
|Pest=Xanthomonas campestris pv. campestris
|Quarantined=No
}}
{{Pest record
|Pest=Xanthomonas campestris
|Quarantined=No
}}