title: Effects of FlrBC on flagellar biosynthesis of Shewanella oneidensis.
abstract: As a most conserved complex molecular machine made up of a large number of structural subunits, the flagellum is under tight regulation by hierarchical arrangements. Although variations in polar flagellar systems are found, most of them are restricted to multiple-copy components, such as flagellins and stators. Therefore, these features are regarded to be peripheral relative to the comprehensive conservation. In this study, however, we present evidence to show that the difference in highly conserved polar flagellar systems can be surprisingly profound, even at the heart of the classical regulatory hierarchy. In Gram-negative Shewanella oneidensis, two-component system FlrBC, whose counterpart is essential for flagellar biosynthesis and motility by directly controlling expression of class III genes in polarly flagellated bacteria such as Vibrio cholerae, is dispensable for the process. The system directly controls expression of the flaA gene, encoding a flagellin of weak motility. We further show that the ratio of two flagellins, FlaA and FlaB, determines motility of a flagellum. More strikingly, overproduction of FlrC results in a peritrichously multi-flagellated phenotype, and FlrC is likely to function as an activator in its unphosphorylated form for transcription of the flaA gene, contrasting the previously characterized counterpart.
authors: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China; Key Laboratory for Agro-Microbial Research and Utilization, Hangzhou, 310058, Zhejiang, China.
authors: Miaomiao
authors: M
authors: Shi
authors: Tong
authors: T
authors: Gao
authors: Lili
authors: L
authors: Ju
authors: Yanlai
authors: Y
authors: Yao
authors: Haichun
authors: H
authors: Gao
mesh_terms: D005407:Flagella / Q000378:metabolism*; D005408:Flagellin / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D010766:Phosphorylation; D020592:Shewanella / Q000502:physiology*
chemical_list: D005408:Flagellin; C067138:flaA protein, bacteria; C416532:flaB flagellin