Deng Yinyue, Wu Jien, Yin Wenfang, Li Peng, Zhou Jianuan, Chen Shaohua, He Fei, Cai Jun, Zhang Lian-Hui
Guangdong Innovative and Entepreneurial Research Team of Sociomicrobiology Basic Science and Frontier Technology, South China Agricultural University, Guangzhou, 510642, China.
Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore, 138673, Singapore.
Environ Microbiol. 2016 May;18(5):1534-45. doi: 10.1111/1462-2920.13244. Epub 2016 Apr 7.
Diffusible signal factor (DSF) represents a new class of widely conserved quorum sensing signals, which regulates various biological functions through intra- or interspecies signaling. The previous studies identified that there is an antagonistic interaction between Xanthomonas and Bacillus species bacteria in natural ecosystem, but the detailed molecular mechanism of interspecies competition is not clear. This study showed that Xanthomonas campestris pv. campestris (Xcc) interfered with morphological transition and sporulation of Bacillus thuringiensis in mixed cultures, whereas abrogation of the DSF synthase RpfF reduced the interference. DSF inhibited B. thuringiensis cell division and sporulation through modulation of ftsZ, which encodes an important cell division protein in bacterial cells. In addition, RpfF is essential for production of six DSF-family signals in Xcc, which employ the same signaling pathways to regulate biological functions in Xcc and play similar effects on reduction of cell division, sporulation and antibiotic resistance of B. thuringiensis. Furthermore, abrogation of RpfF decreased the competitive capability of Xcc against B. thuringiensis on the surface of Chinese cabbage leaves. Our findings provide new insights into the role of DSF-family signals in interspecies competition and depict molecular mechanisms with which Xcc competes with B. thuringiensis.
可扩散信号因子（DSF）代表了一类新的广泛保守的群体感应信号，它通过种内或种间信号传导调节各种生物学功能。先前的研究表明，在自然生态系统中，黄单胞菌属和芽孢杆菌属细菌之间存在拮抗相互作用，但种间竞争的详细分子机制尚不清楚。本研究表明，野油菜黄单胞菌野油菜致病变种（Xcc）在混合培养中会干扰苏云金芽孢杆菌的形态转变和孢子形成，而DSF合酶RpfF的缺失则会降低这种干扰。DSF通过调节ftsZ来抑制苏云金芽孢杆菌的细胞分裂和孢子形成，ftsZ编码细菌细胞中一种重要的细胞分裂蛋白。此外，RpfF对于Xcc中六种DSF家族信号的产生至关重要，这些信号利用相同的信号通路来调节Xcc中的生物学功能，并且对降低苏云金芽孢杆菌的细胞分裂、孢子形成和抗生素抗性具有类似作用。此外，RpfF的缺失降低了Xcc在大白菜叶片表面对苏云金芽孢杆菌的竞争能力。我们的研究结果为DSF家族信号在种间竞争中的作用提供了新的见解，并描述了Xcc与苏云金芽孢杆菌竞争的分子机制。
