title: Genome scale analysis of diffusible signal factor regulon in Xanthomonas campestris pv. campestris: identification of novel cell-cell communication-dependent genes and functions.
abstract: The bacterial pathogen Xanthomonas campestris pv. campestris (Xcc) recruits a diffusible signal factor (DSF), which has recently been structurally characterized as cis-11-methyl-2-dodecenoic acid, as a cell-cell communication signal to synchronize virulence gene expression and biofilm dispersal. In this study, we showed that despite the existance of phenotype variations in different Xcc isolates, the DSF-mediated functions were in general conserved. To investigate the genomic profiles of DSF regulation, we designed and conducted oligomicroarray analysis by comparison of the gene expression patterns of wild-type strain XC1 and its DSF-deficient mutant XC1dF, as well as those of XC1dF in the presence or absence of DSF signals. The analyses led to identification of 165 genes, whose expression was significantly influenced by DSF signals. These genes encode proteins and enzymes belonging to at least 12 functional groups. In addition to those previously known DSF-dependent activities such as production of extracellular enzymes and extracellular polysaccharides, microarray analyses also revealed new functions mediated by DSF, such as flagellum synthesis, resistance to toxins and oxidative stress, and aerobic respiration. Phenotype analyses confirmed that DSF signalling contributed to resistance to toxin acriflavin and hydrogen peroxide, and to the survival of bacterial cells at different temperatures. We conclude that DSF cell-cell signalling is not only essential for co-ordinating the expression of virulence genes but also plays a vital role in keeping up the general competence of the pathogen in ecosystems.
authors.affiliation: Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673.
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: He
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.forename: Kui
authors.initials: K
authors.lastname: Lin
authors.forename: Yu-Jin Alvin
authors.initials: YJ
authors.lastname: Ng
authors.forename: Chao-Ming
authors.initials: CM
authors.lastname: Wen
authors.forename: Lian-Hui
authors.initials: LH
authors.lastname: Wang
authors.forename: Zi-Duo
authors.initials: ZD
authors.lastname: Liu
authors.forename: Hai-Bao
authors.initials: HB
authors.lastname: Zhang
authors.forename: Yi-Hu
authors.initials: YH
authors.lastname: Dong
authors.forename: J Maxwell
authors.initials: JM
authors.lastname: Dow
authors.forename: Lian-Hui
authors.initials: LH
authors.lastname: Zhang
mesh_terms: D001483:Base Sequence; D002450:Cell Communication / Q000235:genetics*; D017931:DNA Primers; D016680:Genome, Bacterial; D009154:Mutation; D018085:Regulon; D016959:Xanthomonas campestris / Q000235:genetics*
chemical_list: D017931:DNA Primers