GENE EXPRESSION DURING SPORULATION

描述（由申请人提供）：细胞分化是一个基本的生物学过程。其核心是在不同细胞类型中建立不同的基因表达程序以及基因表达与形态变化的协调。枯草芽孢杆菌形成孢子是一种原始的细胞分化系统，由于其易于遗传操作，已成为研究原核生物细胞分化的范例。在所有已测序的芽孢科物种中，包括病原体炭疽芽孢杆菌和艰难梭菌，也鉴定出了孢子形成的所有关键调节因子。孢子形成过程包括分裂成两种不同的细胞类型，母细胞和孢子前。前孢子被母细胞吞没，发育成成熟的、具有抗性的孢子。孢子形成需要四种RNA聚合酶，分别是孢子前的sigmaF和sigmaG，然后是母细胞的sigmaa。这里的主要目的是了解区隔化基因表达是如何建立和维持的，以及基因表达是如何与形态变化协调的。大多数建议集中在枯草芽孢杆菌上。将进行一系列相互关联的研究。我们提出要研究为什么sigmaG活性在spolladdelta突变体中从孢子前切换到母细胞。我们建议使用我们开发的两部分区隔化测试来鉴定和表征孢子前特异性表达所需的分裂基因和sF激活调节因子。有人提出要调查为什么某些sf导向基因在染色体末端附近重新定位时表达不良。我们建议鉴定和表征参与sigmaF和sigmaG活性的时间控制的基因。与芽孢杆菌和梭状芽孢杆菌的孢子分裂位置不对称形成鲜明对比的是，我们提出了在孢子分裂位于中间位置的脲孢杆菌中研究区隔化的建立。

DESCRIPTION (provided by applicant): Cell differentiation is a fundamental biological process. Central to it are the establishment of distinct programs of gene expression in the different cell types and the coordination of gene expression with morphological change. Formation of spores by Bacillus subtilis is a primitive system of cell differentiation that has become a paradigm for the study of cell differentiation in prokaryotes because of the ease of its genetic manipulation. All the key regulators of spore formation are also identified in all sequenced species of Bacillaceae, including the pathogens Bacillus anthracis and Clostridium difficile. Sporulation involves a characteristic division into two distinct cell types, the mother cell and the prespore. The prespore is engulfed by the mother cell and develops into the mature, resistant spore. Sporulation requires the action of four RNA polymerase sigma factors, sigmaF and then sigmaG in the prespore and sigmaE and then in sigmak the mother cell. The major objectives here are to understand how compartmentalized gene expression is established and maintained and how gene expression is coordinated with morphological change. Most of the proposal centers on B. subtilis. A series of interconnected lines of research will be pursued. It is proposed to investigate why sigmaG activity switches from the prespore to the mother cell in spollAdelta mutants. It is proposed to identify and characterize division genes and regulators of sF activation that are required for prespore-specific expression using a two-part compartmentalization test we have developed. It is proposed to investigate why certain sF-directed genes are poorly expressed when they are relocated near the chromosome terminus. It is proposed to identify and characterize genes involved in temporal control of sigmaF and sigmaG activity. It is proposed to investigate the establishment of compartmentalization in Sporosarcina ureae where the sporulation division is medially located, in contrast to its grossly asymmetric location for species of Bacillus and Clostridium.