Forespore Engulfment During B subtilis Sporulation

来自芽孢杆菌属和梭菌属的细菌产生异常持久且寿命长的孢子， 炭疽和肉毒杆菌中毒的传染媒介，聚集在另一个细胞的细胞质中。 这种独特的细胞结构（内生孢子）是由一种类似吞噬作用的过程产生的， 吞没在吞噬过程中，较大的母细胞的膜围绕较小的母细胞迁移， 前孢子，直到它被完全包围在母细胞的细胞质中。吞噬提供了一个戏剧性的 这是细菌细胞动态能力的一个例子，但其机制仍不清楚。我们有 为研究吞噬、膜融合和蛋白质定位开发了新的工具， 突变体在这些步骤中有缺陷。融合缺陷突变体在吞噬的最后一步 和细胞分裂，并影响一个保守的蛋白质也参与了染色体的最后阶段， 种族隔离我们认为，这些蛋白质协调染色体分离与完成细胞 分裂，以确保细胞分离不会损害不完全分离的染色体。我们有 我还确定了两种机制，其中一个取决于膜围绕前孢子移动， SpollD肽聚糖水解酶。我们将把细胞生物学、遗传学和生物化学结合起来， 方法来研究肽聚糖水解的空间调节，蛋白质-蛋白质相互作用， 介导吞噬，以及了解细菌细胞催化膜的机制 融合并动态组织。吞噬为研究细胞生物学提供了一个新的系统 这些事件对所有细菌都是必不可少的，例如蛋白质定位和膜融合。它还要求 肽聚糖水解酶，其存在于合成肽聚糖的所有细菌中，并且 因为它们的活性可导致细胞裂解而没有严格的空间和时间调节，所以它们可能是致命的。 事实上，许多商业抗生素的致命性需要这些水解酶。吞噬提供了 这是了解细菌如何控制这些潜在致命酶的理想系统， 新抗生素的靶点，并有可能在蛋白质中识别新的药物靶点， 细菌膜或介导细菌蛋白的定位。

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 (the endospore) is produced by a phagocytosis-like process known as engulfment. During engulfment, 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. We have developed new tools for the study of engulfment, membrane fusion and protein localization and identified mutants defective in these steps. The fusion defective mutant is defective in both the final step of engulfment and cell division, and affects a conserved protein also involved in the final stages of chromosome segregation. We suggest that these proteins coordinate chromosome segregation with the completion of cell division, to ensure that cell separation does not damage an incompletely segregated chromosome. We have also identified two mechanisms by which the membranes move around the forespore, one of which depends on the SpollD peptidoglycan hydrolase. We will take a combined cell biological, genetic and biochemical approach to study the spatial regulation of peptidoglycan hydrolysis, the protein-protein interactions that mediate engulfment, as well as to understand the mechanisms by which bacterial cells catalyze membrane fusion and are dynamically organized. Engulfment provides a dispensable system to study cell biological events that are essential for all bacteria, such as protein localization and membrane fusion. It also requires peptidoglycan hydrolases, which are found in all bacteria that synthesize peptidoglycan, and which are potentially lethal because their activity can result in cell lysis without strict spatial and temporal regulation. Indeed, the lethality of many commercial antibiotics requires these hydrolytic enzymes. Engulfment provides an ideal system for understanding how bacteria control these potentially lethal enzymes, which are attractive targets for novel antibiotics, and has the potential to identify new drug targets in proteins that remodel bacterial membranes or mediate localization of bacterial proteins.