title: Identification of an operon, Pil-Chp, that controls twitching motility and virulence in Xylella fastidiosa.
abstract: Xylella fastidiosa is an important phytopathogenic bacterium that causes many serious plant diseases, including Pierce's disease of grapevines. Disease manifestation by X. fastidiosa is associated with the expression of several factors, including the type IV pili that are required for twitching motility. We provide evidence that an operon, named Pil-Chp, with genes homologous to those found in chemotaxis systems, regulates twitching motility. Transposon insertion into the pilL gene of the operon resulted in loss of twitching motility (pilL is homologous to cheA genes encoding kinases). The X. fastidiosa mutant maintained the type IV pili, indicating that the disrupted pilL or downstream operon genes are involved in pili function, and not biogenesis. The mutated X. fastidiosa produced less biofilm than wild-type cells, indicating that the operon contributes to biofilm formation. Finally, in planta the mutant produced delayed and less severe disease, indicating that the Pil-Chp operon contributes to the virulence of X. fastidiosa, presumably through its role in twitching motility.
authors.affiliation: Department of Plant Pathology and Palnt-Microbe Biology, Cornell University -- New York State Agricultural Experimental Station, Geneva, NY 14456, USA.
authors.forename: Luciana
authors.initials: L
authors.lastname: Cursino
authors.forename: Cheryl D
authors.initials: CD
authors.lastname: Galvani
authors.forename: Dusit
authors.initials: D
authors.lastname: Athinuwat
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Zaini
authors.forename: Yaxin
authors.initials: Y
authors.lastname: Li
authors.forename: Leonardo
authors.initials: L
authors.lastname: De La Fuente
authors.forename: Harvey C
authors.initials: HC
authors.lastname: Hoch
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Burr
authors.forename: Patricia
authors.initials: P
authors.lastname: Mowery
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development; D004269:DNA, Bacterial / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D005798:Genes, Bacterial; D054884:Host-Pathogen Interactions / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009068:Movement / Q000502:physiology; D009154:Mutation; D009876:Operon; D010935:Plant Diseases / Q000382:microbiology*; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics; D027843:Vitis / Q000382:microbiology; D044167:Xylella / Q000235:genetics* / Q000472:pathogenicity* / Q000502:physiology / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial