Vfr targets promoter of genes encoding methyl-accepting chemotaxis protein in Pseudomonas syringae pv. tabaci 6605

Abstract

Virulence factor regulator (Vfr) is an indispensable transcription factor in the expression of virulence in the phytopathogenic bacteria Pseudomonas syringae . However, the function of Vfr is not known so far. The deletion of vfr resulted in the loss of surface swarming motility and reduced the virulence in P . syringae pv. tabaci ( Pta ) 6605. In order to identify the target genes of Vfr, we screened the sequences that bind to Vfr by chromatin immune precipitation (ChIP) and sequencing methods using the closely related bacterium P . syringae pv. syringae ( Pss ) B728a. For this purpose we first generated a strain that possesses the recombinant gene vfr :: FLAG in Pss B728a, and performed ChIP using an anti-FLAG antibody. Immunoprecipitated DNA was purified and sequenced with Illumina HiSeq. The Vfr::FLAG-specific peaks were further subjected to an electrophoresis mobility-shift assay, and the promoter regions of locus tag for Psyr_0578 , Psyr_1776, and Psyr_2237 were identified as putative target genes of Vfr. These genes encode plant pathogen–specific methyl-accepting chemotaxis proteins (Mcp). These mcp genes seem to be involved in the Vfr-regulated expression of virulence.