Lv Mingfa, Ye Sixuan, Hu Ming, Xue Yang, Liang Zhibin, Zhou Xiaofan, Zhang Lianhui, Zhou Jianuan
Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China.
College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
Front Plant Sci. 2022 Oct 21;13:1033192. doi: 10.3389/fpls.2022.1033192. eCollection 2022.
Phytopathogen is a causal agent of rice foot rot disease and the pathogen has an array of virulence factors, such as phytotoxin zeamines, plant cell wall degrading enzymes, cell motility, and biofilms, collectively contributing to the bacterial pathogenesis. In this study, through deletion analysis of predicted regulatory genes in EC1, we identified a two-component system associated with the regulation of bacterial virulence. The two-component system contains a histidine kinase ArcB and a response regulator ArcA, and deletion of their coding genes resulted in changed phenotypes in cell motility, biofilm formation, and bacterial virulence. Electrophoretic mobility shift assay revealed that ArcA bound to the promoters of the operon and , which respectively encode enzymes for the synthesis of celluloses and a biofilm formation regulatory protein. ArcA could also bind to the promoters of three virulence associated transcriptional regulatory genes, i.e., , and . Surprisingly, although these three regulators were shown to modulate the production of cell wall degrading enzymes and zeamines, deletion of and did not seem to affect these phenotypes. Taken together, the findings from this study unveiled a new two-component system associated with the bacterial pathogenesis, which contributes to the virulence of mainly through its action on bacterial motility and biofilm formation.
植物病原体是水稻基腐病的致病因子，该病原体具有一系列毒力因子，如植物毒素玉米胺、植物细胞壁降解酶、细胞运动性和生物膜，这些共同促成了细菌的致病过程。在本研究中，通过对EC1中预测的调控基因进行缺失分析，我们鉴定出了一个与细菌毒力调控相关的双组分系统。该双组分系统包含组氨酸激酶ArcB和应答调节因子ArcA，其编码基因的缺失导致细胞运动性、生物膜形成和细菌毒力方面的表型改变。电泳迁移率变动分析表明，ArcA与操纵子和的启动子结合，这两个操纵子分别编码纤维素合成酶和一种生物膜形成调节蛋白。ArcA还能与三个毒力相关转录调控基因即、和的启动子结合。令人惊讶的是，尽管这三个调控因子被证明可调节细胞壁降解酶和玉米胺的产生，但和的缺失似乎并未影响这些表型。综上所述，本研究的结果揭示了一个与细菌致病过程相关的新双组分系统，该系统主要通过对细菌运动性和生物膜形成的作用来促进的毒力。
