Mutations in Type I and Type IV Pilus Biosynthetic Genes Affect Twitching Motility Rates in Xylella fastidiosa

Abstract

Xylella fastidiosa possesses both type I and type IV pili at the same cell pole. By use of a microfluidic device, the speed of twitching movement by wild-type cells on a glass surface against the flow direction of media was measured as 0.86 (standard error [SE], 0.04) μm min ⁻¹ . A type I pilus mutant ( fimA ) moved six times faster (4.85 [SE, 0.27] μm min ⁻¹ ) and a pilY1 mutant moved three times slower (0.28 [SE, 0.03] μm min ⁻¹ ) than wild-type cells. Type I pili slow the rate of movement, while the putative type IV pilus protein PilY1 is likely important for attachment to surfaces.