Bacterial cell wall synthesis, shape and septation

描述（由申请人提供）：除了保护细菌免于裂解外，肽聚糖细胞壁在几个生理过程中起着重要的作用，但未被充分认识。从产生细胞极性、影响分化和阻止病毒进入的基本生物学功能，到促进宿主附着、毒素产生和先天免疫反应的识别。人们对细菌形态在营养积累、附着、运动、染色体分离、捕食、生物膜形成和毒力方面的贡献了解得更少。我们的长期目标是了解肽聚糖的结构、合成、调控和功能含义，以及产生和修饰肽聚糖的酶。特别是，我们一直在寻找低分子量青霉素结合蛋白的生理功能，这是一个大家族的肽聚糖修饰酶，以多种形式存在，在细菌王国中高度保守。这些酶与细菌分裂蛋白FtsZ相互作用，通过独立于或先于由FtsZ启动的经典分裂途径的反应，产生具有明确和均匀形状的细胞。重要的是，在多重突变菌株中新描述的表型允许通过以前无法用于此类研究的遗传技术来解决细胞形状和极性的问题。我们建议通过追求以下具体目标来完善和表征这种“形态途径”的功能：1)表征FtsZ在惰性肽聚糖的生成和定位中的作用；2)描述肽聚糖水解酶在细胞形态和完整性中的作用；3)定义相互作用的螺旋结构如何推动壁和包膜的生长；4)分离和表征抑制突变体，以更详细地定义形态学途径。这些目标将通过创建缺乏所提出途径部分的菌株，通过分析现有的FtsZ突变体并创建新的突变体，以及通过分离抑制突变体来定义该途径的其他成分来实现。

DESCRIPTION (provided by applicant): In addition to protecting bacteria from lysis, the peptidoglycan cell wall plays an important, underappreciated role in several physiological processes. These range from the basic biological functions of creating cellular polarity, influencing differentiation and impeding virus entry, to contributing to host attachment, toxin production and recognition by the innate immune response. Even less well understood are the contributions of bacterial morphology to nutrient accumulation, attachment, motility, chromosome segregation, predation, biofilm formation and virulence. Our long-term goal is to understand the structure, synthesis, regulation and functional implications of peptidoglycan and the enzymes that create and modify it. In particular, we've been searching for the physiological functions of the low molecular weight penicillin binding proteins, a large family of peptidoglycan-modifying enzymes that are present in multiple forms and highly conserved across the bacterial kingdom. These enzymes interact with the bacterial division protein, FtsZ, to create cells of defined and uniform shape via reactions that are either independent of or which precede the now-classic division pathway initiated by FtsZ. Of great import is that newly described phenotypes in multiply-mutated strains allow questions of cell shape and polarity to be approached by genetic techniques not previously available for such studies. We propose to refine and characterize the functioning of this "morphological pathway" by pursuing the following specific aims: 1) characterize the role of FtsZ in generating and localizing inert peptidoglycan; 2) characterize the roles of peptidoglycan hydrolases in cell shape and integrity; 3) define how interacting helical structures propel growth of the wall and envelope; and 4) isolate and characterize suppressor mutants to define the morphological pathway in more detail. These goals will be realized by creating strains deficient in portions of the proposed pathway, by assaying current FtsZ mutants and creating new ones, and by isolating suppressor mutants to define additional components of the pathway.