Flagellar biogenesis of Xanthomonas campestris requires the alternative sigma factors RpoN2 and FliA and is temporally regulated by FlhA, FlhB, and FlgM.
In prokaryotes, flagellar biogenesis is a complicated process involving over 40 genes. The phytopathogen Xanthomonas campestris pv. campestris possesses a single polar flagellum, which is essential for the swimming motility. A sigma54 activator, FleQ, has been shown to be required for the transcriptional activation of the flagellar type III secretion system (F-T3SS), rod, and hook proteins. One of the two rpoN genes, rpoN2, encoding sigma54, is essential for flagellation. RpoN2 and FleQ direct the expression of a second alternative sigma FliA (sigma28) that is essential for the expression of the flagellin FliC. FlgM interacts with FliA and represses the FliA regulons. An flgM mutant overexpressing FliC generates a deformed flagellum and displays an abnormal motility. Mutation in the two structural genes of F-T3SS, flhA and flhB, suppresses the production of FliC. Furthermore, FliA protein levels are decreased in an flhB mutant. A mutant defective in flhA, but not flhB, exhibits a decreased infection rate. In conclusion, the flagellar biogenesis of Xanthomonas campestris requires alternative sigma factors RpoN2 and FliA and is temporally regulated by FlhA, FlhB, and FlgM.
Yang
Tsuey-Ching
TC
Department of Biotechnology, Asia University, Wufeng, Taichung County, Taiwan.
Leu
Yu-Wei
YW
Chang-Chien
Hui-Chen
HC
Hu
Rouh-Mei
RM
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051877:RNA Polymerase Sigma 54 / Q000235:genetics / Q000378:metabolism*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D016959:Xanthomonas campestris / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; C080688:FlhA protein, Bacteria; C085668:FlhB protein, Bacteria; C064971:FliA protein, Bacteria; D008565:Membrane Proteins; D012808:Sigma Factor; C071266:FlgM protein, Bacteria; D051877:RNA Polymerase Sigma 54