IasB is Essential for Surface Motility in P. aeruginosa

描述（由申请人提供）：铜绿假单胞菌是一种普遍存在的重要机会性病原体，具有令人印象深刻的毒力因子库。弹性蛋白酶是一种由lasB基因编码的金属蛋白酶，通过降解或使组织和免疫系统成分失活而产生毒力。lasB的表达既需要群体感应（QS）系统，也需要群体感应（PQS）系统。人们对弹性蛋白酶在这种细菌的生命中所起的作用知之甚少。我们的实验室最近发现了lasB突变细胞严重缺乏抽搐和群体运动的证据，并在这里首次提出。表面相关的运动对细菌种群的生存和扩散至关重要，在生物膜的形成中起着决定性的作用。拟议的研究将探讨弹性蛋白酶影响这两种运动形式的机制。抽搐运动依赖于PilT介导的IV型菌毛的收缩。lasB突变细胞的菌毛收缩受到抑制，因此我们将重点研究lasB影响菌毛收缩的机制。群体运动既需要鞭毛也需要鼠李糖脂。鞭毛的数量和位置在lasB突变细胞上发生改变。此外，lasB突变细胞产生较少的c4 -高丝氨酸内酯（HSL）。鼠李糖脂、pyocyanin和pyoverdin的产生都由rhl群体感应系统控制，C4-HSL是其同源信号。lasB基因本身受QS调控，拟议的研究旨在确定弹性蛋白酶如何影响P. aeruginosa中AHL的产生。lasB突变的多效性效应最好通过涉及微阵列和蛋白质组学分析的全局方法来解决。拟议的研究结果将有助于更好地了解LasB是如何在宿主组织开发中至关重要的重要毒力因子，也有助于该细菌的表面相关运动性，生物膜形成和QS调节。

DESCRIPTION (provided by applicant): Pseudomonas aeruginosa is a ubiquitous and important opportunistic pathogen that possesses an impressive arsenal of virulence factors. Elastase, a metalloprotease encoded by the lasB gene, contributes to virulence by degrading or inactivating tissue and immune system components. The expression of lasB requires both the las quorum-sensing (QS) system and PQS. Little is known about the role elastase plays in the life of this bacterium. Evidence that lasB mutant cells are severely deficient in both twitching and swarming motility was recently discovered in our lab and is presented here for the first time. Surface associated motility is essential for survival and dispersal of bacterial populations and plays a defining role in biofilm formation. The proposed research will investigate the mechanism(s) by which elastase affects these two forms of motility. Twitching motility is dependent upon PilT mediated retraction of the Type IV pilus. Pilus retraction is inhibited in lasB mutant cells, thus our studies will focus on the mechanism by which LasB affects pilus retraction. Swarming motility requires both flagella and rhamnolipids. The number and position of flagella are altered on lasB mutant cells. Additionally, lesser amounts of C4-homoserine lactone (HSL) are produced by lasB mutant cells. The production of rhamnolipids, pyocyanin, and pyoverdin are all controlled by the rhl quorum-sensing system for which C4-HSL is the cognate signal. The lasB gene itself is regulated by QS and the proposed research seeks to determine how elastase affects AHL production in P. aeruginosa. The pleiotropic effects of the lasB mutation are best addressed by a global approach involving microarray and proteomic analyses which are proposed. The results of the proposed research will lead to a greater understanding of how LasB, an important virulence factor that is crucial in host tissue exploitation, also contributes to surface-associated motility, biofilm formation and QS regulation in this bacterium.