title: Regulation of the synthesis of cyclic glucan in Xanthomonas campestris by a diffusible signal molecule.
abstract: The rpf gene cluster of Xanthomonas campestris pv. campestris is involved in the co-ordinate positive regulation of the production of extracellular enzymes and the extracellular polysaccharide xanthan. Several of the rpf genes are involved in a regulatory system involving the small diffusible molecule DSF (for diffusible signal factor). Synthesis of DSF requires RpfF, and a two-component sensory transduction system involving RpfC has been implicated in the perception of the signal and signal transduction. Here we show that mutations in both rpfF and rpfC lead to reductions in the levels of cyclic glucan. The levels of cyclic glucan synthetase in membrane preparations from rpfF and rpfC mutants were, however, unaltered from the wild-type. Similar alterations in the level of cyclic glucan without changes in cyclic glucan synthetase activity were seen when wild-type bacteria were exposed to osmotic stress. These results extend the range of cellular functions subject to regulation by the rpf genes and DSF system.
authors.affiliation: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
authors.forename: A A
authors.initials: AA
authors.lastname: Vojnov
authors.forename: H
authors.initials: H
authors.lastname: Slater
authors.forename: M A
authors.initials: MA
authors.lastname: Newman
authors.forename: M J
authors.initials: MJ
authors.lastname: Daniels
authors.forename: J M
authors.initials: JM
authors.lastname: Dow
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D004058:Diffusion; D015964:Gene Expression Regulation, Bacterial; D005936:Glucans / Q000032:analysis / Q000096:biosynthesis*; D005810:Multigene Family; D009154:Mutation; D009997:Osmotic Pressure; D015398:Signal Transduction; D016959:Xanthomonas campestris / Q000235:genetics / Q000378:metabolism*; D047071:beta-Glucans
chemical_list: D001426:Bacterial Proteins; D005936:Glucans; D047071:beta-Glucans; C089202:cyclic (1-6)-(1-3)-glucan; C102500:rpfC protein, Xanthomonas