Zhou Mimi, Shen Danyu, Xu Gaoge, Liu Fengquan, Qian Guoliang
College of Plant Protection (Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, No. 1 Weigang, Nanjing, 210095, Jiangsu, People's Republic of China.
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, People's Republic of China.
Curr Microbiol. 2017 May;74(5):566-574. doi: 10.1007/s00284-017-1202-5. Epub 2017 Mar 3.
Lysobacter enzymogenes (L. enzymogenes) is an agriculturally important Gram-negative bacterium that employs T4P (type IV pili)-driven twitching motility to exhibit its antifungal function. Yet, it is still unclear how this bacterium regulates its twitching motility. Here, by using strain OH11 as the working model organism, we showed that a hybrid two-component system ChpA acts as a positive regulator in controlling twitching motility in L. enzymogenes. ChpA is a hybrid TCS (two-component transduction system) contains 7 domains including those for auto-phosphorylation and phosphate group transfer, as well as a phosphate receiver (REC) domain. Mutation of chpA completely abolished the wild-type twitching motility, as evidenced by the absence of mobile cells at the margin of the mutant colonies. Further studies of domain-deletion and phenotypic characterization reveal that domains responsible for phosphorylation and phosphotransfer, but not the REC domain, were indispensable for ChpA in regulating twitching motility. Transcriptome analyses of the chpA knockout strain indicated that ChpA was extensively involved in controlling expression of a wide variety of genes (totaling 243). The products of these differentially expressed genes were involved in multiple physiological and biological functions in L. enzymogenes. Thus, we have not only identified a new regulator controlling twitching motility in L. enzymogenes, but also provided the first report demonstrating the broad impact of the conserved ChpA in gene regulation in Gram-negative bacteria.
食酸菌（Lysobacter enzymogenes，L. enzymogenes）是一种在农业领域具有重要意义的革兰氏阴性菌，它利用IV型菌毛（T4P）驱动的颤动运动来发挥其抗真菌功能。然而，目前仍不清楚这种细菌如何调节其颤动运动。在此，我们以OH11菌株作为模式生物，发现一种混合型双组分系统ChpA在调控食酸菌的颤动运动中起到正向调节作用。ChpA是一种混合型双组分转导系统（TCS），包含7个结构域，其中包括自磷酸化和磷酸基团转移结构域，以及一个磷酸受体（REC）结构域。chpA突变完全消除了野生型的颤动运动，这在突变菌落边缘没有游动细胞得到证实。进一步的结构域缺失和表型特征研究表明，负责磷酸化和磷酸转移的结构域而非REC结构域，对于ChpA调节颤动运动是不可或缺的。对chpA基因敲除菌株的转录组分析表明，ChpA广泛参与控制多种基因（共计243个）的表达。这些差异表达基因的产物参与了食酸菌的多种生理和生物学功能。因此，我们不仅鉴定出一种控制食酸菌颤动运动的新调节因子，还首次报道了保守的ChpA在革兰氏阴性菌基因调控中的广泛影响。
