title: The role of PilZ domain proteins in the virulence of Xanthomonas campestris pv. campestris.
abstract: Cyclic di-GMP [(bis-(3'-5')-cyclic di-guanosine monophosphate)] is an almost ubiquitous second messenger in bacteria that is implicated in the regulation of a range of functions that include developmental transitions, aggregative behaviour, adhesion, biofilm formation and virulence. Comparatively little is known about the mechanism(s) by which cyclic di-GMP exerts these various regulatory effects. PilZ has been identified as a cyclic di-GMP binding protein domain; proteins with this domain are involved in regulation of specific cellular processes, including the virulence of animal pathogens. Here we have examined the role of PilZ domain proteins in virulence and the regulation of virulence factor synthesis in Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot of crucifers. The Xcc genome encodes four proteins (XC0965, XC2249, XC2317 and XC3221) that have a PilZ domain. Mutation of XC0965, XC2249 and XC3221 led to a significant reduction of virulence in Chinese radish. Mutation of XC2249 and XC3221 led to a reduction in motility whereas mutation of XC2249 and XC0965 affected extracellular enzyme production. All mutant strains were unaffected in biofilm formation in vitro. The reduction of virulence following mutation of XC3221 could not be wholly attributed to an effect on motility as mutation of pilA, which abolishes motility, has a lesser effect on virulence.
authors.affiliation: BIOMERIT Research Centre, Department of Microbiology, BioSciences Institute, National University of Ireland, Cork, Ireland.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: McCarthy
authors.forename: Robert P
authors.initials: RP
authors.lastname: Ryan
authors.forename: Karen
authors.initials: K
authors.lastname: O'Donovan
authors.forename: Yong-Qiang
authors.initials: YQ
authors.lastname: He
authors.forename: Bo-Le
authors.initials: BL
authors.lastname: Jiang
authors.forename: Jia-Xun
authors.initials: JX
authors.lastname: Feng
authors.forename: Ji-Liang
authors.initials: JL
authors.lastname: Tang
authors.forename: J Maxwell
authors.initials: JM
authors.lastname: Dow
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology; D009154:Mutation; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D031224:Raphanus / Q000382:microbiology; D014774:Virulence / Q000235:genetics / Q000502:physiology*; D016959:Xanthomonas campestris / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C022994:cyclic GMP-binding protein; D006152:Cyclic GMP