Regulation of Stationary Phase in Escherichia coli

描述（由申请人提供）：肠道细菌如大肠杆菌一生中大部分时间都在缺乏一种或多种必需营养素。为了在饥饿条件下生存，这些细菌进入一种称为静止期的非生长状态。固定相位的主调节器是备用的初级σ因子RpoS。在快速生长的细胞中，RpoS水平较低，因为孤儿反应调节剂SprE （RssB）靶向RpoS，使其被CIpP/X蛋白酶降解。我们发现，当细菌缺乏碳时，RpoS水平会增加，因为RpoS的降解停止了。对磷的缺乏也会导致RpoS水平升高，但在这种情况下，由于RpoS mRNA翻译的增加，RpoS水平升高。相反，缺氮并不会导致RpoS水平的增加；相反，RpoS活动增加了。我们建议结合遗传、生化、代谢组学和计算方法来识别介导这些不同营养剥夺反应的关键信号和效应分子。由于已知RpoS对某些细菌的发病机制很重要，因此对细菌如何进入和退出静止期的详细了解可能会揭示这些病原体盔甲中的裂缝。此外，由于中枢代谢的途径在整个生物学中都是保守的，我们认为触发过渡到非生长状态的信号也可能是保守的。因此，在细菌中获得的见解可能会揭示真核微生物，甚至动物细胞中的类似过程。

DESCRIPTION (provided by applicant): Enteric bacteria such as Escherichia coli spend most of their lifetimes starved for one or more essential nutrients. To survive environmental challenges under starvation conditions these bacteria enter a non-growing state called stationary phase. The master regulator of stationary phase is the alternate primary sigma factor RpoS. In rapidly growing cells RpoS levels are low because the orphan response regulator SprE (RssB) targets RpoS for degradation by the CIpP/X protease. We have discovered that when bacteria are starved for carbon, RpoS levels increase because RpoS degradation stops. Starvation for phosphorus also results in elevated levels of RpoS, but in this case levels are elevated because of an increase in rpoS mRNA translation. In contrast starvation for nitrogen does not cause an increase in RpoS levels; rather, RpoS activity is increased. We propose a combination of genetic, biochemical, metabolomic, and computational methods to identify the key signaling and effector molecules that mediate these diverse responses to nutrient deprivation. Since RpoS is known to be important for the pathogenesis of certain bacteria, a detailed understanding of how bacteria enter and exit stationary phase may reveal chinks in the armor of these pathogens. In addition, because the pathways of central metabolism are conserved throughout biology, we think that the signals that trigger transition to a non-growing state may be conserved as well. Thus insights gained in bacteria may shed light on similar processes in eukaryotic microbes, and perhaps animal cells as well.