"Xylella fastidiosa pil-chp operon" is involved in regulating key structural genes of both type I and IV pili

• Lingyun Hao ^[1] ; D. Athinuwat ^[1] ; K. Johnson ^[1] ; L. Cursino ^[2] ; T. J. Burr ^[1] ; P. Mowery ^[2]
  1. [1] Cornell University

     Cornell University

     City of Ithaca, Estados Unidos

     
  2. [2] Hobart and William Smith Colleges

     Hobart and William Smith Colleges

     City of Geneva, Estados Unidos

     
• Localización: Vitis: Journal of Grapevine Research, ISSN 0042-7500, Vol. 56, Nº 2, 2017, págs. 55-62
• Idioma: inglés
• Enlaces
  • Texto completo
• Resumen
  • español

    Xylella fastidiosa, pil-chp, Pierce's disease, PilG, PilJ, type I pili, type IV pili

  • English

    Xylella fastidiosa is the causal agent of Pierce's disease (PD) in grapevines. It has type I and type IV pili, which are both virulence factors involved in the PD-associated processes of motility, aggregation, and biofilm formation. Many questions remain as to how the two pili are regulated. We previously identified a X. fastidiosa pil-chp chemosensory-like cluster as an operon composed of genes pilG-I-J-L-chpB-C. In this study, we deleted pilG (resulting in a ∆pilG-I strain) and pilJ and discovered that both mutants (∆pilG-I and ∆pilJ) had reduced virulence after 24 weeks post-inoculation, whereas ∆chpB and ∆chpC did not. Both ∆pilG-I and ∆pilJ lost motility and were impaired in biofilm formation in rich artificial media and xylem sap. Gene expression was significantly downregulated for representative fimbrial adhesin and motility genes in ∆pilG-I, and to a lesser extent in ∆pilJ. Our data suggest that Pil, but not Chp, proteins are virulence factors, and pilG-I-J are involved in transcriptional regulation of type I and IV pili virulence genes and therefore motility and biofilm formation. To our knowledge, this is the first report of a chemotaxis-like operon involved in the regulation of key structural genes of both type I and type IV pili.