Public Health Research Center, New Jersey Medical School, 225 Warren Street, Newark, NJ 07103, USA.
Mol Microbiol. 2013 Apr;88(2):283-300. doi: 10.1111/mmi.12186. Epub 2013 Mar 12.
Bacillus subtilis has adopted a bet-hedging strategy to ensure survival in changing environments. From a clonal population, numerous sub-populations can emerge, expressing different sets of genes that govern the developmental processes of sporulation, competence and biofilm formation. The master transcriptional regulator Spo0A controls the entry into all three fates and the production of the phosphorylated active form of Spo0A is precisely regulated via a phosphorelay, involving at least four proteins. Two proteins, YmcA and YlbF were previously shown to play an unidentified role in the regulation of biofilm formation, and in addition, YlbF was shown to regulate competence and sporulation. Using an unbiased proteomics screen, we demonstrate that YmcA and YlbF interact with a third protein, YaaT to form a tripartite complex. We show that all three proteins are required for proper establishment of the three above-mentioned developmental states. We show that the complex regulates the activity of Spo0A in vivo and, using in vitro reconstitution experiments, determine that they stimulate the phosphorelay, probably by interacting with Spo0F and Spo0B. We propose that the YmcA-YlbF-YaaT ternary complex is required to increase Spo0A~P levels above the thresholds needed to induce development.
枯草芽孢杆菌采取了一种“赌注式生存”的策略，以确保在不断变化的环境中生存。从一个克隆群体中，可以出现许多亚群，表达不同的基因集，这些基因集控制着芽孢形成、感受态和生物膜形成的发育过程。主要转录调节剂 Spo0A 控制着所有三种命运的进入，并且 Spo0A 的磷酸化活性形式的产生是通过磷酸传递精确调节的，涉及至少四种蛋白质。先前已经证明，两种蛋白质 YmcA 和 YlbF 在生物膜形成的调节中发挥了未知的作用，此外，YlbF 被证明调节感受态和芽孢形成。使用无偏蛋白质组学筛选，我们证明 YmcA 和 YlbF 与第三种蛋白质 YaaT 相互作用形成三元复合物。我们表明，所有三种蛋白质都是正确建立上述三种发育状态所必需的。我们表明，该复合物在体内调节 Spo0A 的活性，并通过体外重组实验确定它们通过与 Spo0F 和 Spo0B 相互作用来刺激磷酸传递。我们提出，YmcA-YlbF-YaaT 三元复合物是必需的，以将 Spo0A~P 水平提高到诱导发育所需的阈值以上。
