Wu W, Zhao Z, Luo X, Fan X, Zhuo T, Hu X, Liu J, Zou H. 2018. Response regulator VemR regulates the transcription of flagellar rod gene flgG by interacting with σ54 factor RpoN2 in Xanthomonas citri subsp. citri. Molecular Plant Pathology

  发布时间: 2018-11-05   信息员:   


Xanthomonas citri subsp. citri, a polarly flagellated bacterium, causes citrus canker disease worldwide. In this study, we found that the X. citri subsp. citri response regulator VemR plays a regulatory role in flagellum-derived cell motility. Deletion of the vemR gene resulted in a reduction in cell motility, as well as reductions in virulence and exopolysaccharide production. RT-PCR demonstrated that vemR is transcribed in an operon together with rpoN2 and fleQ. In the vemR mutant, the flagellar distal rod gene flgG was significantly downregulated. Because flgG is also rpoN2-dependent, we speculated that VemR and RpoN2 physically interact, which was confirmed with yeast two-hybrid and GST pull-down assays. This suggested that the transcription of flgG is synergistically controlled by VemRand RpoN2. To confirm this, we constructed a vemR and rpoN2 double mutant. In this mutant, the reductions in cell motility and flgG transcription were unable to be restored by the expression of either vemR or rpoN2 alone. In contrast, expression of both vemR and rpoN2 together in the double mutant restored the wild-type phenotype. Together, our data demonstrate that the response regulator VemR functions as an RpoN2 cognate activator to positively regulate the transcription of the rod gene flgG in X. citri subsp. citri.