Fatty acid DSF binds and allosterically activates histidine kinase RpfC of phytopathogenic bacterium Xanthomonas campestris pv. campestris to regulate quorum-sensing and virulence

• DOI: 10.1371/journal.ppat.1006304
• Publication Date: 2017-04-03T21:50:53Z
• Authors: Zhen Cai; Zhi-Hui Yuan; Huan Zhang; Yue Pan; Yao Wu; Xiu-Qi Tian; Fang-Fang Wang; Li Wang; Wei Qian
• Keywords: Histidine kinase; Xanthomonas

As well as their importance to nutrition, fatty acids (FA) represent a unique group of quorum sensing chemicals that modulate the behavior bacterial population in virulence. However, way which full-length, membrane-bound receptors biochemically detect FA remains unclear. Here, we provide genetic, enzymological and biophysical evidences demonstrate phytopathogenic bacterium Xanthomonas campestris pv. campestris, medium-chain diffusible signal factor (DSF) binds directly N-terminal, 22 amino acid-length sensor region receptor histidine kinase (HK), RpfC. The binding event remarkably activates RpfC autokinase activity by causing an allosteric change associated with dimerization phosphotransfer (DHp) catalytic ATP-binding (CA) domains. Six residues were found essential for DSF, especially those located adjoining inner membrane cells. Disrupting direct DSF-RpfC interaction caused deficiency virulence biofilm development. In addition, two within juxtamembrane domain RpfC, Leu172 Ala178, are involved autoinhibition activity. Replacements them constitutive activation RpfC-mediated signaling regardless DSF stimulation. Therefore, our results revealed biochemical mechanism whereby HK manner, will assist future studies on specificity FA-HK recognition during regulation cell-cell communication.