Pseudomonas aeruginosa quorum sensing

项目摘要 群体感应(QS)是一种广泛分布的细胞间通信方法，由细菌用来 协调小组活动。人类条件致病菌铜绿假单胞菌利用qs调节 大量分泌产物的生产，其中包括毒力因子、抗生素和蛋白酶。这个 铜绿假单胞菌作为一个群体改变其行为的能力导致了治疗这种细菌的困难 囊性纤维化等疾病，在这些疾病中它会造成慢性呼吸道感染。在铜绿假单胞菌中，qs是 部分由转录因子LasR和RhlR介导，它们对酰基高丝氨酸内酯产生反应 信号。在实验室菌株中，LasR调节RhlR，它们共同控制数百个 基因。LasR突变在CF中很常见(尽管RhlR突变通常不被观察到)，这意味着 这些分离物中的qs失活。然而，在许多囊性纤维化铜绿假单胞菌分离株中，RhlR活性 不依赖于LasR，许多LasR缺失的分离物仍然进行酰基高丝氨酸内酯QS。 这些菌株中活性的RhlR QS的存在意味着QS对于某些 肺循环内的因素。这项建议使用了大量囊性纤维化铜绿假单胞菌的分离株。 患者探索铜绿假单胞菌的适应，以保留QS，尽管LasR突变。这些实验 问：1)受QS转录因子调控的基因是什么？ 临床分离株的“核心”QS调控；2)允许LasR非依赖性RhlR的基因变化是什么 这些临床分离株的活性以及RhlR的直接基因靶点是什么？以及3)什么是 阻止RhlR突变在铜绿假单胞菌种群中出现的分子机制？ 对这些问题的回答将给出临床上铜绿假单胞菌QS的更完整的图景，并指导 针对QS或QS调节基因的努力，以管理和治疗人类疾病中的细菌种群。

Project Summary Quorum sensing (QS) is a broadly distributed intercellular communication method used by bacteria to coordinate group activities. The opportunistic human pathogen Pseudomonas aeruginosa uses QS to regulate the production of numerous secreted products that include virulence factors, antibiotics, and proteases. The ability of P. aeruginosa to alter its behavior as a group contributes to the difficulty of treating this bacterium in diseases such as cystic fibrosis, in which it establishes chronic airway infections. In P. aeruginosa, QS is mediated in part by the transcription factors LasR and RhlR, which respond to acyl-homoserine lactone signals. In laboratory strains, LasR regulates RhlR, and together they control the transcription of hundreds of genes. LasR mutants are common in CF (although RhlR mutants are not usually observed) implying inactivation of QS in these isolates. However, in many P. aeruginosa isolates from cystic fibrosis, RhlR activity is not dependent on LasR and many LasR-null isolates still engage in acyl-homoserine lactone QS. The presence of active RhlR QS in these strains implies that QS is important for the regulation of certain factors within the CF lung. This proposal uses a large collection of P. aeruginosa isolates from cystic fibrosis patients to explore adaptations P. aeruginosa makes to preserve QS despite lasR mutation. The experiments described in this proposal ask: 1) what are the genes regulated by QS transcription factors and what is the “core” QS regulon of clinical isolates; 2) what are the genetic changes that allow for LasR-independent RhlR activation in these clinical isolates and what are the direct gene targets of RhlR?; and 3) what are the molecular mechanisms that prevent RhlR mutants from emerging in populations of P. aeruginosa? The answers to these questions will give a more complete picture of QS in clinical P. aeruginosa, and guide efforts to target QS or QS-regulated genes to manage and treat bacterial populations in human disease.