Lombardía Esteban, Rovetto Adrián J, Arabolaza Ana L, Grau Roberto R
Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario (2000), Argentina.
J Bacteriol. 2006 Jun;188(12):4442-52. doi: 10.1128/JB.00165-06.
Cell-to-cell communication in bacteria is mediated by quorum-sensing systems (QSS) that produce chemical signal molecules called autoinducers (AI). In particular, LuxS/AI-2-dependent QSS has been proposed to act as a universal lexicon that mediates intra- and interspecific bacterial behavior. Here we report that the model organism Bacillus subtilis operates a luxS-dependent QSS that regulates its morphogenesis and social behavior. We demonstrated that B. subtilis luxS is a growth-phase-regulated gene that produces active AI-2 able to mediate the interspecific activation of light production in Vibrio harveyi. We demonstrated that in B. subtilis, luxS expression was under the control of a novel AI-2-dependent negative regulatory feedback loop that indicated an important role for AI-2 as a signaling molecule. Even though luxS did not affect spore development, AI-2 production was negatively regulated by the master regulatory proteins of pluricellular behavior, SinR and Spo0A. Interestingly, wild B. subtilis cells, from the undomesticated and probiotic B. subtilis natto strain, required the LuxS-dependent QSS to form robust and differentiated biofilms and also to swarm on solid surfaces. Furthermore, LuxS activity was required for the formation of sophisticated aerial colonies that behaved as giant fruiting bodies where AI-2 production and spore morphogenesis were spatially regulated at different sites of the developing colony. We proposed that LuxS/AI-2 constitutes a novel form of quorum-sensing regulation where AI-2 behaves as a morphogen-like molecule that coordinates the social and pluricellular behavior of B. subtilis.
细菌中的细胞间通讯由群体感应系统（QSS）介导，该系统产生称为自诱导物（AI）的化学信号分子。特别是，已提出依赖LuxS/AI-2的QSS作为一种通用词汇，介导种内和种间细菌行为。在此我们报告，模式生物枯草芽孢杆菌运行一种依赖luxS的QSS，该系统调节其形态发生和社会行为。我们证明，枯草芽孢杆菌luxS是一个受生长阶段调控的基因，它产生能够介导哈氏弧菌种间光产生激活的活性AI-2。我们证明，在枯草芽孢杆菌中，luxS表达受一个新的依赖AI-2的负调控反馈环控制，这表明AI-2作为信号分子发挥重要作用。尽管luxS不影响孢子发育，但AI-2的产生受多细胞行为的主要调控蛋白SinR和Spo0A的负调控。有趣的是，来自未驯化的益生菌纳豆芽孢杆菌菌株的野生枯草芽孢杆菌细胞需要依赖LuxS的QSS来形成强大且分化的生物膜，以及在固体表面上群体游动。此外，LuxS活性是形成复杂气生菌落所必需的，这些菌落表现为巨大的子实体，其中AI-2的产生和孢子形态发生在发育中的菌落的不同位点受到空间调控。我们提出，LuxS/AI-2构成了一种群体感应调节的新形式，其中AI-2表现为一种形态发生素样分子，协调枯草芽孢杆菌的社会和多细胞行为。
