Forespore Engulfment During B. subtilis Sporulation

枯草芽孢杆菌孢子形成过程中前孢子的吞噬

• 批准号: 6837721
• 负责人: Kit J Pogliano
• 金额: $ 30.31万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6837721
• 关键词: Forespore; Engulfment; During; B.; subtilis

EXCEED THE SPACE PROVIDED. Bacteria from the genera Bacillus and Clostridium produce unusually durable and long lived spores that are the infectious agent of Anthrax and Botulism, and which are assembled in the cytoplasm of another cell. This unique cell within a cell structure is produced by the phagocytosis-like process of engulfment, during which the membrane of the larger mother cell migrates around the smaller forespore, until it is completely enclosed within the mother cell cytoplasm. Engulfment provides a dramatic example of the dynamic capabilities of the bacterial cell, but its mechanism remains unclear. Previously, the only engulfment mutants blocked septal thinning, during which peptidoglycan within the septum is thinned in preparation for membrane migration. We have developed new tools for the study of engulfment, and identified mutants defective in membrane migration, and in the final step of engulfment, membrane fusion. The membrane fusion defective mutants affect a protein that is both highly conserved and essential in many species. This protein localizes to site of division and is involved in the final stages of chromosome segregation, suggesting that it may also be involved in membrane fusion at the completion of cell division, a process about which little is known. Sporulation-specific enzymes are required to hydrolyze peptidoglycan during septal thinning, and we will test if vegetative autolysins can partially substitute for the sporulation specific enzymes. Autolysins are found in all bacteria (the Bacillus subtilis genome is predicted encode more than 30 such enzymes), and are thought to allow peptidoglycan remodeling for cell elongation and division. However, these enzymes are potentially lethal, since unless they are tightly regulated both spatially and temporally, their activity can result in cell lysis. Indeed, the lethality of many commercial antibiotics requires autolysins. Engulfment provides an ideal system for understanding how bacteria control these potentially lethal enzymes, which are attractive targets for novel antibiotics. We will take a combined cell biological, genetic and biochemical approach to study the spatial regulation of peptidoglycan hydrolysis, the mechanism of membrane fusion in bacterial cells, as well as to understand how bacteria move and localize macromolecules within their cells. PERFORMANCE SITE ========================================Section End===========================================

超出所提供的空间。 芽孢杆菌属和梭状芽孢杆菌属的细菌产生异常耐用且寿命长的孢子，这些孢子是炭疽和肉毒杆菌的传染源，并在另一个细胞的细胞质中组装。细胞结构中的这种独特的细胞是通过类似吞噬作用的吞噬过程产生的，在此过程中，较大母细胞的膜在较小的前孢子周围迁移，直到它完全封闭在母细胞的细胞质内。吞噬提供了细菌细胞动态能力的一个引人注目的例子，但其机制仍不清楚。此前，唯一的吞噬突变体阻止了隔膜变薄，在此期间隔膜内的肽聚糖变薄，为膜迁移做准备。我们开发了用于研究吞噬的新工具，并鉴定了膜迁移和吞噬的最后一步（膜融合）有缺陷的突变体。膜融合缺陷突变体影响一种在许多物种中高度保守且必需的蛋白质。这种蛋白质定位于分裂位点，并参与染色体分离的最后阶段，这表明它也可能参与细胞分裂完成时的膜融合，而这一过程目前知之甚少。在隔膜变薄过程中，需要孢子形成特异性酶来水解肽聚糖，我们将测试植物自溶素是否可以部分替代孢子形成特异性酶。自溶素存在于所有细菌中（枯草芽孢杆菌基因组预计编码超过 30 种此类酶），并且被认为允许肽聚糖重塑以促进细胞伸长和分裂。然而，这些酶可能是致命的，因为除非它们在空间和时间上受到严格调控，否则它们的活性可能会导致细胞裂解。事实上，许多商业抗生素的致死性需要自溶素。吞噬提供了一个理想的系统来了解细菌如何控制这些潜在致命的酶，这些酶是新型抗生素的有吸引力的目标。我们将采用细胞生物学、遗传学和生化相结合的方法来研究肽聚糖水解的空间调控、细菌细胞膜融合的机制，以及了解细菌如何在细胞内移动和定位大分子。表演网站==========================================章节结束===============================================