The Significance of Xylella fastidiosa Type I and Type IV pili in Biofilm Structure, Bacterial Survival in Biofilms, and in DNA Secretion and Uptake

PIs: Thomas Burr, Harvey Hoch

• Final report submitted on Aug. 9, 2008
• Progress report submitted on March 10, 2008

Research Papers

• Type I and type IV pili of Xylella fastidiosa affect twitching motility, biofilm formation and cell-cell aggregation
  Xylella fastidiosa, an important phytopathogenic bacterium, causes serious plant diseases including Pierce's disease of grapevine. It is reported here that type I and type IV pili of X fastidiosa play different roles in twitching motility, biofilm formation and cell-cell aggregation. Type I pili are particularly important for biofilm formation and aggregation, whereas type IV pili are essential for motility, and also function in biofilm formation. Thirty twitching-defective mutants were generated with an EZ: : TN transposome system, and several type-IV-pilus-associated genes were identified, including fimT, pilX, pilY1, pilO and pilR. Mutations in fimT, pilX, pilO or pilR resulted in a twitch-minus phenotype, whereas the pilY1 mutant was twitching reduced. A mutation in fimA resulted in a biofilm-defective and twitching-enhanced phenotype. A fimA/pilO double mutant was twitch minus, and produced almost no visible biofilm. Transmission electron microscopy revealed that the pili, when present, were localized to one pole of the cell. Both type I and type IV pili were present in the wild-type isolate and the pilY1 mutant, whereas only type I pili were present in the twitch-minus mutants. The fimA mutant produced no type I pili. The fimA/pilO double mutant produced neither type I nor type IV pili.
  March 1, 2007
  

Funding sources:

• Funded by: UC PD Fund
• Budget: $229,814.00
• Start date: July 15, 2007
• Stop date: July 14, 2009
• Status: APPROVED