title: High-resolution transcriptional analysis of the regulatory influence of cell-to-cell signalling reveals novel genes that contribute to Xanthomonas phytopathogenesis.
abstract: The bacterium Xanthomonas campestris is an economically important pathogen of many crop species and a model for the study of bacterial phytopathogenesis. In X. campestris, a regulatory system mediated by the signal molecule DSF controls virulence to plants. The synthesis and recognition of the DSF signal depends upon different Rpf proteins. DSF signal generation requires RpfF whereas signal perception and transduction depends upon a system comprising the sensor RpfC and regulator RpfG. Here we have addressed the action and role of Rpf/DSF signalling in phytopathogenesis by high-resolution transcriptional analysis coupled to functional genomics. We detected transcripts for many genes that were unidentified by previous computational analysis of the genome sequence. Novel transcribed regions included intergenic transcripts predicted as coding or non-coding as well as those that were antisense to coding sequences. In total, mutation of rpfF, rpfG and rpfC led to alteration in transcript levels (more than fourfold) of approximately 480 genes. The regulatory influence of RpfF and RpfC demonstrated considerable overlap. Contrary to expectation, the regulatory influence of RpfC and RpfG had limited overlap, indicating complexities of the Rpf signalling system. Importantly, functional analysis revealed over 160 new virulence factors within the group of Rpf-regulated genes.
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, UK.
authors.forename: Shi-Qi
authors.initials: SQ
authors.lastname: An
authors.forename: Melanie
authors.initials: M
authors.lastname: Febrer
authors.forename: Yvonne
authors.initials: Y
authors.lastname: McCarthy
authors.forename: Dong-Jie
authors.initials: DJ
authors.lastname: Tang
authors.forename: Leah
authors.initials: L
authors.lastname: Clissold
authors.forename: Gemy
authors.initials: G
authors.lastname: Kaithakottil
authors.forename: David
authors.initials: D
authors.lastname: Swarbreck
authors.forename: Ji-Liang
authors.initials: JL
authors.lastname: Tang
authors.forename: Jane
authors.initials: J
authors.lastname: Rogers
authors.forename: J Maxwell
authors.initials: JM
authors.lastname: Dow
authors.forename: Robert P
authors.initials: RP
authors.lastname: Ryan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D054884:Host-Pathogen Interactions; D010935:Plant Diseases / Q000382:microbiology*; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism; D037521:Virulence Factors / Q000096:biosynthesis; D016959:Xanthomonas campestris / Q000235:genetics / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins; C419552:RpfG protein, Xanthomonas campestris; D014157:Transcription Factors; D037521:Virulence Factors; C102500:rpfC protein, Xanthomonas