REGULATION OF THE MAJOR OUTER MEMBRANE PORIN PROTEINS

描述：大肠杆菌两种主要孔蛋白的合成， OmpF和OmpC由复杂的重叠调节机制控制 每一个都对关键的环境线索做出反应。 因此，孔蛋白调节子 提供了一个强有力的实验系统， 细菌适应的分子机制。 了解这些机制 将揭示细菌盔甲上的裂缝， 与传染病作无休止的斗争。 OmpR/EnvZ双组分信号转导系统调控转录 两个孔蛋白结构基因的相互作用， 渗透压 我们的遗传分析揭示了结构基序， 重要的是由每个调节蛋白执行的多种功能。 在OmpR的情况下，我们的数据与最近确定的 DNA结合域的三维结构。 但重要 OmpR与DNA、OmpR与RNA之间的相互作用 聚合酶仍然存在。 我们提出具体的遗传实验来解决这些问题 问题. 我们与EnvZ的合作有助于澄清机械差异 在这种原型的相反的激酶和磷酸酶活性之间， 传感器. 未来的实验将使用遗传和物理方法， 试着去理解这种膜蛋白是如何感知媒体的 渗透压 MicF是一种反义RNA，它可以阻止mRNA的翻译， 当某些有毒分子如胆汁盐被 礼物 我们将使用micF-lacZ融合研究其机制， 上调这种反义RNA的合成以响应生长 温度 此外，RpoS（固定相位sigma因子）阻止 在精心编程的努力中， 当细胞面对不可预测的压力时， 饥饿后可能出现的症状 我们发现了两个新的 蛋白质，SprE和Crl，其功能是控制稳定性和活性 的RPoS。 遗传学和生物化学实验被提议用于 阐明这些新的调控机制。

DESCRIPTION: Synthesis of the two major porin protein of Escherichia coli, OmpF and OmpC, is controlled by complex, overlapping regulatory mechanisms that each respond to key environmental cues. Accordingly, the porin regulon provides a powerful experimental system for studying the integrated molecular mechanisms of bacterial adaptation. Knowledge of these mechanisms will reveal chinks in the bacterial armor that can be exploited in our never-ending fight against infectious disease. The OmpR/EnvZ two-component signal transduction system control transcription of both porin structural genes in reciprocal fashion in response to media osmolarity. Our genetic analysis has revealed structural motifs that are important for the multiple functions performed by each regulatory protein. In the case of OmpR, our data fit beautifully with the recently determined three-dimensional structure of the DNA-binding domain. However, important questions about the interactions between OmpR and DNA, and OmpR and RNA polymerase remain. We propose specific genetic experiments to address these issues. Our work with EnvZ has helped clarify the mechanistic difference between the opposed kinase and phosphatase activities of this prototypic sensor. Future experiments here will use genetic and physical methods to try and understand how this integral membrane protein senses media osmolarity. MicF, an antisense RNA, prevents translation of the mRNA for the larger porin, OmpF, when certain toxic molecules such as bile salts are present. We will use micF-lacZ fusions to investigate the mechanism that upregulates synthesis of this antisense RNA in response to growth temperature. In addition, RpoS, the stationary phase sigma factor, blocks transcription of ompF during an elaborately programmed effort to maximize changes for survival when the cell is faced with the unpredictable stresses that might occur following starvation. We have discovered two novel proteins, SprE and Crl, that function to control the stability and activity of RpoS respectively. Genetic and biochemical experiments are proposed to elucidate these novel regulatory mechanisms.