Cell Division in a Filamentous, Sporulating Bacterium

为了在细胞周期中正确的时间和正确的位置沉积隔膜，单细胞细菌必须能够监测DNA复制的完成和新复制DNA的分离，定位细胞中心，并启动新细胞壁和细胞质膜的向心生长。因为二元裂变是大多数细菌繁殖的唯一方式，许多细胞分裂所需的基因是必不可少的，因此不能轻易地通过突变分析来剖析。与其他细菌不同的是，链霉菌以分枝、丝状、多核细胞的形式生长，这些细胞经历多次分裂形成孢子链。链霉菌分化的关键事件包括形成注定成为孢子的室室所必需的大量和相对同步的分离，以及分化结构在分离之前的广泛生长。为了鉴定导致细胞结构剧烈变化的结构蛋白、酶和调节蛋白，本项目重点研究孢子间隔形成所需的两种蛋白：FtsZ和间隔特异性青霉素结合蛋白。这些实验将通过综合报告系统、突变体分析和ftsZ转录所需的蛋白质分析，确定与灰色链霉菌ftsZ发育调控有关的因素。分离稻瘟病菌隔区特异性青霉素结合蛋白的编码基因并测定其核苷酸序列；在另一个实验中，这个基因将被破坏，以确认它在隔膜形成中的作用。细胞分裂是所有生物的基本特性。为了繁殖，每个细胞必须分裂产生有活力的子细胞。丝状细菌细胞分裂的分析是一个逻辑系统，用于研究细胞分裂的正确时间和位置的核心分子事件。通过描述这些细菌的细胞分裂机制，这项研究将有助于建立细胞生长的基础。

Kendrick 9724038 To deposit a septum at the correct time in the cell cycle and at the correct location, a unicellular bacterium must be able to monitor the completion of DNA replication and the segregation of the newly replicated DNA, locate the center of the cell, and initiate the centripetal growth of new cell wall and cytoplasmic membrane. Because binary fission is the only means by which most commonly studied bacteria reproduce, many of the genes required for cell division are essential and thus cannot be readily dissected by mutation analysis. Unlike other bacteria, Streptomyces grows as branched, filamentous, multinucleoidal cells that undergo multiple septation events to form chains of spores. Key events in Streptomyces differentiation include the massive and relatively synchronous septation necessary to form the compartments destined to become the spores, and the extensive growth of the differentiated structures prior to septation. To identify structural, enzymatic, and regulatory proteins responsible for this dramatic change in cell structure, this project focuses on two proteins required for sporulation septum formation: FtsZ and the septum-specific penicillin-binding protein. These experiments will identify the factors involved in the developmental regulation of ftsZ in Streptomyces griseus by using an integrative reporter system, mutant analysis, and the analysis of proteins required for transcription of ftsZ. The gene encoding the septum-specific penicillin-binding protein of S.griseus will be isolated and its nucleotide sequence determined; in another experiment this gene will be disrupted to confirm its role in septum formation. Cell division is an essential property of all organisms. To reproduce, each cell must divide to generate viable daughter cells. The analysis of cell division in filamentous bacteria is a logical system to use to study molecular events central to the correct timing and location of cell division. By characterizing the cell division machine ry in these bacteria, this research will help to build the cornerstones of cell growth.