Mechanisms Governing Bacillus Mother Cell Gene Expression

描述（由申请人提供）：本研究的目的是了解细菌中基因表达是如何在时间和空间上受到调节的。枯草芽孢杆菌的产孢提供了一个有吸引力的实验系统来阐明可能被其他细菌（包括病原体）使用的信号传导和基因调控的新机制。在产孢过程中，细胞分为母细胞室和前孢子室，每个室都有基因组的拷贝。RNA聚合酶（RNAP）的不同sigma亚基在不同的时间在每个隔室中活跃，在很大程度上解释了时间和空间的基因调控。此外，转录因子激活或抑制许多基因的表达。本研究的重点是母细胞区室的基因调控机制，其中两个sigma因子和两个转录因子按照sigmaE、SpoIIID、sigmaK、GerE的顺序按等级级联组织。每个sigma的活性受一个独特的信号通路控制，该信号通路始于前孢子，结束于母细胞中抑制前序列的蛋白水解去除。这些信号通路的组成部分是已知的，但信号传导和蛋白水解过程的分子机制仍有待阐明。目的之一是了解pro-sigmaK加工的机制以及美国银行对其的监管。该途径涉及SpoIVFB金属蛋白酶对pro-sigmaK的膜内蛋白水解（RIP）调控。RIP参与了关键的生物过程，但人们对其了解甚少。pro-sigmaK的RIP由SpoIVFB提供了一个极好的机会来开辟新天地。pro-sigmaE的加工似乎不涉及RIP，但其机制及其由前孢子信号调控的机制尚不清楚。为了阐明这一途径，将应用成功研究前符号加工的方法。另一个目的是研究sigmaK RNAP负性调控早期基因表达的反馈回路的重要性。这将使我们深入了解从一个调控子到另一个调控子的转换，这是细菌和噬菌体基因调控的一个共同特征。最后，spoiid的小尺寸和在孢子形成中的重要作用使其对结构/功能和遗传分析具有吸引力，这将增加对细菌转录激活机制的了解。

DESCRIPTION (provided by applicant): The objective of this research is to understand how gene expression is regulated temporally and spatially in bacteria. Sporulation of Bacillus subtilis provides an attractive experimental system to elucidate novel mechanisms of signaling and gene regulation likely to be used by other bacteria, including pathogens. During sporulation, the cell is divided into mother cell and forespore compartments, each with a copy of the genome. Different sigma subunits of RNA polymerase (RNAP) become active in each compartment at different times, accounting for much of the temporal and spatial gene regulation. In addition, transcription factors activate or repress expression of many genes. This proposal focuses on mechanisms of gene regulation in the mother cell compartment, where two sigma factors and two transcription factors are organized in a hierarchical cascade with the order sigmaE, SpoIIID, sigmaK, then GerE. Activity of each sigma is governed by a unique signaling pathway that begins in the forespore and ends with proteolytic removal of an inhibitory pro-sequence in the mother cell. Components of these signaling pathways are known, but the molecular mechanisms of signaling and proteolytic processing remain to be elucidated. One aim is to understand the mechanism of pro-sigmaK processing and its regulation by BofA. This pathway involves regulated intramembrane proteolysis (RIP) of pro-sigmaK by SpoIVFB metalloprotease. RIP is involved in crucial biological processes, but is poorly understood. RIP of pro-sigmaK by SpoIVFB provides a fantastic opportunity to break new ground. Processing of pro-sigmaE does not appear to involve RIP, but its mechanism and its regulation by a signal from the forespore are unclear. To clarify this pathway, approaches used successfully to study pro-sigmaK processing will be applied. Another aim is to investigate the importance of a feedback loop by which sigmaK RNAP negatively regulates early gene expression. This will give insight into the switch from one regulon to another, a common feature in bacterial and phage gene regulation. Finally, SpoIIID's small size and essential role in sporulation make it attractive for structure/function and genetic analyses that will add knowledge about mechanisms of transcriptional activation in bacteria.