Temporal and Spatial Control of B subtilis cytokinesis

描述（由申请人提供）：细胞如何决定何时何地分裂仍然是现代生物学的一大谜团。在空间上，严格控制分隔，以确保隔片的准确定位。在时间上，分裂与DNA复制和染色体分离相协调。从细菌到酵母再到人类，细胞分裂都是通过在新生分裂位点形成细胞骨架蛋白环来启动的。该环确定了分隔隔膜的位置，并用作分隔装置组装的框架。在细菌中，该环由必需的微管蛋白样GTftsZ组成。该建议侧重于土壤细菌B中FtsZ环形成的调控网络。枯草杆菌。建立分裂位点并将FtsZ环形成与细胞周期结合的因素仍然未知。理解细菌分裂的空间和时间调节，因此需要识别的细胞和分子机制，刺激FtsZ环形成在中细胞响应细胞周期的线索，并抑制FtsZ环形成在所有其他网站。 EzrA是一种有助于限制FtsZ环形成于中细胞的因子，通过经典遗传筛选鉴定。初步的生物化学数据表明，EzrA直接与FtsZ相互作用，通过FtsZ聚合物的不稳定来抑制环的形成。这项建议有三个主要目标。第一，表征EzrA防止异位FtsZ环形成的分子机制。第二，克隆wee 2基因并对其进行鉴定。wee 2是一种突变，它使细胞分裂与生长分离，导致小细胞的形成，许多细胞的大小不到野生型B的25%。枯草杆菌。第三，扩展遗传筛选，以确定其他因素，（i）促进FtsZ环形成在中间细胞，（ii）耦合FtsZ环形成的细胞周期，和（iii）抑制FtsZ环形成在不适当的网站。 作为细菌细胞分裂机制的重要组成部分，FtsZ及其活性调控因子有望成为开发新抗生素的潜在靶点。此外，这项工作不仅应该阐明细菌细胞分裂，而且还对所有生物体都至关重要的胞质分裂方面。了解通常控制细胞分裂的分子机制将有助于确定为什么它们在肿瘤发生过程中失败，导致癌细胞的异常分裂和快速增殖。

DESCRIPTION (provided by applicant): How cells determine when and where to divide remains one of the great mysteries of modern biology. Spatially, division is tightly regulated to ensure the accurate positioning of septa. Temporally, division is coordinated with DNA replication and chromosome segregation. From bacteria to yeast to humans, cell division is initiated by the formation of a ring of a cytoskeletal protein at the nascent division site. This ring establishes the location of the division septum and serves as a framework for assembly of the division apparatus. In bacteria this ring is composed of the essential tubulin-like GTPase FtsZ. This proposal focuses on the regulatory networks that govern FtsZ ring formation in the soil bacterium B. subtilis. The factors that establish the division site and couple FtsZ ring formation to the cell cycle remain unknown. Comprehending the spatial and temporal regulation of bacterial division thus requires the identification of the cellular and molecular mechanisms that stimulate FtsZ ring formation at midcell in response to cell cycle cues and inhibit FtsZ ring formation at all other sites. EzrA, a factor that helps restrict FtsZ ring formation to midcell, was identified through classical genetic screens. Preliminary biochemical data suggest that EzrA interacts directly with FtsZ to inhibit ring formation by destabilization of FtsZ polymers. This proposal has three major goals. One, to characterize the molecular mechanism by which EzrA prevents ectopic FtsZ ring formation. Two, to clone and to characterize the gene identified by wee2, a mutation that uncouples cell division from growth, leading to the formation of small cells, many less than 25% the size of wild type B. subtilis. Three, to extend genetic screens to identify additional factors that (i) promote FtsZ ring formation at midcell, (ii) couple FtsZ ring formation to the cell cycle, and (iii) inhibit FtsZ ring formation at inappropriate sites. As essential components of the bacterial cell division machinery, FtsZ and the factors governing its activity hold promise as potential targets for the development of new antibiotics. Furthermore, this work should illuminate not only bacterial cell division, but also aspects of cytokinesis fundamental to all organisms. Understanding the molecular mechanisms that normally control cell division will help identify why they fail during oncogenesis, leading to the aberrant divisions and rapid proliferation characteristic of cancer cells.