Physiological role of RpoS-controlled functions of Escherichia coli

增加我们对细菌基因的了解对于理解细菌生理学和环境适应的基本方面是至关重要的。近年来，关于一种关键的保守调控因子rpos的研究已有很多，但仍有许多未解之谜。我们对受rpos控制的基因的功能还没有完全的了解。为了解决这个问题，我们将使用遗传学和分子生物学工具来检查我们分离的rpos依赖基因的表达。通过同时描述许多依赖rpos的基因，我们将了解这些基因作为一个类别与正常生长所需的所谓管家基因有何不同。除了表征rpos依赖的基因外，我们还将研究我们先前研究中出现的有关赖氨酸脱羧酶、转醛醇酶和过氧化氢酶表达的具体问题。这些稳定的特定基因中的每一个在帮助细胞适应压力条件方面都可能是重要的，因为我们已经发现，它们只在细胞处于饥饿状态时的静止阶段表达--它们在正常条件下不表达。我们还将研究rpos中选定的突变如何有助于细菌细胞的整体适应性，并将使用代谢物分析来发现rpos如何影响在次优生长条件下维持的细菌的代谢物通量。这些研究将扩大我们对细菌持久性和存活率的影响因素的了解。

Increasing our knowledge regarding bacterial genes that are expressed in response to nutrient deprivation or other stresses is crucial for understanding basic aspects of bacterial physiology and environmental adaptation. In recent years, much has been learned about a key conserved regulator, RpoS, that is required for the expression of a large number of stress-induced genes but many unanswered questions remain. We do not have a full understanding of the function of genes controlled by RpoS. To address this, we will use genetic and molecular biology tools to examine the expression of RpoS-dependent genes that we have isolated. By simultaneously characterizing many RpoS-dependent genes, we will learn how these genes differ as a class from so-called housekeeping genes that are required for normal growth. In addition to characterizing RpoS-dependent genes, we will investigate specific questions that have arisen from our previous studies regarding lysine decarboxylase, transaldolase and catalase expression. Each of these stationary-specific genes are probably important in helping the cell adapt to stress conditions since we have found that they are expressed only in stationary phase when cells are in a starved state--they are not expressed under normal conditions. We will also examine how selected mutations in RpoS contribute to the overall fitness of the bacterial cell and will use metabolite analysis to discover how RpoS affects metabolite flux in bacteria maintained under suboptimal growth conditions. These studies will extend our knowledge of factors that contribute to bacterial persistence and survival.