Intermembrane Transfer and Assembly of the Type II Secretion System of Gram-Negative Bacteria

革兰氏阴性菌II型分泌系统的膜间转移和组装

• 批准号: 203383-2012
• 负责人: Howard, Peter
• 金额: $ 2.48万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=569943
• 关键词: Intermembrane; Transfer; Assembly; Type; II

The research programme of our laboratory is concerned with the structure and function of the double membrane envelope of Gram-negative bacteria. We study interactions between the inner and outer membrane as well as the transport of materials across the outer membrane. This transport is a fundamental life process since membranes act as a barrier in protecting the cell, but that barrier must be overcome so that nutrients and proteins required for life can cross them. The major focus of our current research is the structure and function of the type two secretion system (T2SS) that allows Gram negative bacteria to secrete degradative enzymes and toxins. In our previous studies we showed that a complex of two membrane proteins, ExeAB, are required for the transport and assembly of the secretin, the outer membrane channel through which T2SS proteins are secreted. We have demonstrated that ExeA binds to peptidoglycan, a major structural component of the cell envelope, and identified critical amino acids of the peptidoglycan binding site. In our current experiments, a major focus is how interactions between ExeAB and peptidoglycan allow the secretin to assemble into a channel in the outer membrane. We hypothesize that ExeAB itself forms a multimeric scaffold to which the secretin binds in order to assemble. We are using biochemical and genetic approaches to study the multiple factors involved during secretin assembly in E. coli and V. cholerae. In E. coli we hypothesize that the secretins of the two T2SS systems in this bacterium are assembled independently, whereas in V. cholerae we have evidence that there are at least two different mechanisms involved in assembly of the same secretin, and have identified a candidate for the second, as yet unidentified mechanism. These studies will provide new information concerning how Gram negative bacteria secrete enzymes and protein toxins, and lead to new strategies for harnessing bacterial protein synthesis and for interfering with toxin secretion.

本实验室的研究项目是革兰氏阴性菌双膜被膜的结构和功能。 我们研究了内外膜之间的相互作用以及物质穿过外膜的运输。 这种运输是一个基本的生命过程，因为细胞膜是保护细胞的屏障，但必须克服这一屏障，使生命所需的营养物质和蛋白质可以穿过它们。 我们目前研究的主要焦点是第二型分泌系统（T2SS）的结构和功能，该系统允许革兰氏阴性菌分泌降解酶和毒素。 在我们以前的研究中，我们表明，一个复杂的两个膜蛋白，ExeAB，所需的运输和组装的分泌素，外膜通道，通过T2SS蛋白的分泌。我们已经证明，ExeA结合到肽聚糖，细胞包膜的主要结构组成部分，并确定了肽聚糖结合位点的关键氨基酸。 在我们目前的实验中，一个主要的焦点是ExeAB和肽聚糖之间的相互作用如何允许分泌素组装成外膜中的通道。我们假设ExeAB本身形成一个多聚体支架，分泌素与之结合以组装。 我们正在使用生物化学和遗传学的方法来研究在大肠杆菌中分泌素组装过程中涉及的多种因素。大肠杆菌和霍乱弧菌。在大肠在大肠杆菌中，我们假设该细菌中两个T2SS系统的分泌素是独立组装的，而在霍乱弧菌中，我们有证据表明至少有两种不同的机制参与同一分泌素的组装，并确定了第二种机制的候选者，但尚未确定。 这些研究将提供有关革兰氏阴性菌如何分泌酶和蛋白质毒素的新信息，并导致利用细菌蛋白质合成和干扰毒素分泌的新策略。