Post-translational regulation of type VI secretion in Pseudomonas aeruginosa

描述(申请人提供)：细菌的毒力与其释放分泌因子的能力密切相关。因此，在致病性革兰氏阴性菌(I-VI型)中存在许多进化上不同的蛋白质转位途径。VI型分泌物(T6S)是这些途径中最新描述的，是许多病原菌毒力的重要贡献者。该提案的发起人Joseph Mougous博士首先描述了铜绿假单胞菌的这种分泌系统。这项工作对分泌系统产生了基本的生化和结构洞察；此外，它还提供了证据，证明铜绿假单胞菌的T6S系统(T6SS)对于该菌导致囊性纤维化患者的破坏性慢性感染是重要的。这项建议的重点，也是Mougous博士的实验室的主要研究重点，是了解紧密调控铜绿假单胞菌T6SS活性的调控途径。这一途径类似于真核信号，由跨膜丝氨酸-苏氨酸激酶的二聚化启动。这会引发一系列事件，“触发”分泌系统，导致底物移位。尽管Mougous博士之前的工作已经揭示了这一途径的一些机制细节，但许多关键问题仍然没有答案。拟议的实验试图回答这些机械性的问题，并利用这种新的调节模式来识别分泌系统的底物--这是该领域的当前障碍。许多对人类健康和生物防御具有重要意义的病原体需要T6S来毒力，并使用这一途径来调节其活性；因此，拟议的研究结果将具有广泛的意义，并可能导致新的治疗策略的开发。公共卫生相关性：病原菌利用蛋白质分泌来致病。这项建议的目的是调查一种类型的蛋白质分泌，即VI型分泌(T6S)，是如何在机会性人类病原体铜绿假单胞菌中调节的。这项拟议的研究还试图了解T6S释放的哪些因素有助于其在慢性铜绿假单胞菌感染中的作用。

DESCRIPTION (provided by applicant): The virulence of a bacterium is closely linked to its ability to release secreted factors. It follows that many evolutionarily distinct pathways exist for the translocation of proteins in pathogenic Gram-negative bacteria (types I-VI). Type VI secretion (T6S), the most recently described of these pathways, is an important contributor to the virulence of many pathogenic bacteria. The PI of this proposal, Dr. Joseph Mougous, first characterized this secretion system in Pseudomonas aeruginosa. This work produced fundamental biochemical and structural insights into the secretion system; furthermore, it provided evidence that the T6S system (T6SS) of P. aeruginosa is important for the devastating chronic infections this organism causes in cystic fibrosis patients. The focus of this proposal, and the major research emphasis of Dr. Mougous' laboratory, is to understand the regulatory pathway that tightly modulates the activity of the P. aeruginosa T6SS. This pathway, which is reminiscent of eukaryotic signaling, is initiated by dimerization of a transmembrane serine-threonine kinase. This provokes a series of events that "triggers" the secretion system, leading to substrate translocation. Although prior work by Dr. Mougous has revealed some of the mechanistic details of this pathway, many key questions remain unanswered. The proposed experiments seek to answer these mechanistic questions, and also to utilize this novel mode of regulation for the purpose of identifying substrates of the secretion system - a current impediment to the field. Many pathogens of significance to human health and biodefense require T6S for virulence and use this pathway to regulate its activity; therefore, findings generated by the proposed research will have broad implications and could lead to the development of new therapeutic strategies. PUBLIC HEALTH RELEVANCE: Pathogenic bacteria utilize protein secretion to cause disease. The aims of this proposal investigate how one type of protein secretion, type VI secretion (T6S), is regulated in the opportunistic human pathogen Pseudomonas aeruginosa. The proposed research also seeks to understand what factors released by T6S contribute to its role in chronic P. aeruginosa infections.