Role of RNA Polymerase in Bacterial Differentiation

描述（由申请人提供）：本项目旨在阐明枯草芽孢杆菌孢子形成过程中细胞特异性基因表达的调控机制。孢子形成涉及到一个不对称位置的隔膜的形成。隔膜将发育中的细胞分为前孢子和母细胞，它们遵循不同的基因表达和分化途径。不对称分裂包括将姐妹染色体重塑成一个细长的DNA团块，该DNA团块固定在发育中的细胞的两极，并在称为Z环的细胞动力学结构的形成位置上发生开关，该结构由微管蛋白样蛋白FtsZ组成。我们将通过实验来研究发育蛋白RacA在染色体重塑中的作用，以及ftsz相关蛋白SpollE在细胞极附近Z环形成中的作用。RacA在染色体锚定与极性分裂的检查点机制中的作用也将被研究。转录因子sigmaF在极隔形成后的前孢子中开始活跃。实验将通过SpollE蛋白来研究sF活化与极性隔膜形成的耦合。实验还将探讨控制进入孢子形成的dna结合蛋白Spo0A在不对称分裂后成为母细胞特异性转录因子，并启动母细胞系基因表达的假设。母细胞中的基因表达通过细胞间信号转导途径与前孢子中的基因表达联系的机制，包括膜结合的蛋白加工复合体。其他项目的目标是了解蛋白质亚细胞定位的机制，在全基因组的基础上阐明前孢子和母细胞中的基因表达程序，并研究涉及多细胞相互作用的孢子形成的新发现。这些目标解决了分化和基因控制的基本问题，这些问题在许多种类的发育系统中是共同的，包括高等生物中正常和异常发育的复杂系统。

DESCRIPTION (provided by applicant): The objective of this project is to elucidate the mechanisms that govern cell-specific gene expression during the process of spore formation in the bacterium Bacillus subtilis. Sporulation involves the formation of an asymmetrically positioned septum. The septum divides the developing cell into a forespore and a mother cell, which follow dissimilar pathways of gene expression and differentiation. Asymmetric division involves the remodeling of sister chromosomes into an elongated DNA mass that is anchored to both poles of the developing cell and a switch in the site of formation of a cytokinetic structure called the Z ring, which is composed of the tubulin-like protein FtsZ. Experiments will be carried out to investigate the role of the developmental protein RacA in chromosome remodeling and the role of the FtsZ-associated protein SpollE in the formation of Z rings near the cell poles. The role of RacA in a checkpoint mechanism that links chromosome anchoring to polar division will also be investigated. The transcription factor sigmaF becomes active in the forespore just after the formation of the polar septum. Experiments will be carried out to investigate the coupling of sF activation to the formation of the polar septum via the SpollE protein. Experiments will also be carried out to investigate the hypothesis that the DNA-binding protein Spo0A, which controls entry into sporulation, becomes a mother-cell-specific transcription factor after asymmetric division and sets in motion the mother-cell-line of gene expression. The mechanism by which gene expression in the mother cell is linked to gene expression in the forespore via an intercellular signal transduction pathway involving a membrane-bound proprotein processing complex will be investigated. Other projects are directed at understanding mechanisms of protein subcellular localization, elucidating on a genome-wide basis the programs of gene expression in the forespore and the mother cell, and investigating newly discovered aspects of sporulation involving multicellular interactions. These goals address basic questions of differentiation and gene control that are common to developing systems of many kinds, including complex systems of normal and abnormal development in higher organisms.