ROLE OF A NEW SIGNAL MOLECULE IN P. AERUGINOSA VIRULENCE

铜绿假单胞菌是医院获得性感染患者中最常见的革兰氏阴性菌，在免疫功能低下和囊性纤维化患者中都有很高的死亡率。这种机会性的病原体产生大量的毒力因子，其中一些由作为群体感应的细胞密度监测机制控制。群体感应涉及一种信号分子，即自动诱导剂，它随着细菌密度的增加而积累浓度，直到达到阈值浓度，在那里它结合并激活转录激活蛋白。铜绿假单胞菌使用两个群体感应系统LAS和RHL，通过两个主要的自身诱导剂3-oxo-C12-HSL和C4-HSL来控制众多毒力因子(包括LasB弹性蛋白酶)。最近，第三种诱导分子被命名为假单胞菌喹诺酮信号(PQS)。初步结果表明，PQS受LAS群体感应系统的调节，至少需要Rh1R来诱导lasB。为了阐明PQS的合成途径，g3enes表征了控制PQs表达的因素。为了阐明途径，将研究负责合成邻氨基苯甲酸酯(PQS前体)的基因，并将使用表型和基于LasB产生的表型筛选来克隆其他负责PQS产生的基因。为了确定PQS在铜绿假单胞菌毒力中的作用，将利用报告基因融合来确定PQS如何影响不同毒力基因的表达。最后，为了研究PQS的表达，将使用PQS生物测定来监测其在各种条件下的产生。这项建议的长期目标是确定PQS在铜绿假单胞菌感染发病机制中的作用，希望它将导致治疗铜绿假单胞菌的新的有效方法。

Pseudomonas aeruginosa is the most prevalent Gram negative bacteria found in patient with hospital-acquired infections and produces a high mortality rate in both immunocompromised and cystic fibrosis patients. This opportunistic pathogen produces an arsenal of virulence factors, some of which are controlled by the cell density monitoring mechanism as quorum sensing. Quorum sensing involves a signal molecule, the autoinducer, that builds in concentration with bacterial density until a threshold concentration is reached where it binds and activates a transcriptional activator protein. P. aeruginosa uses two quorum sensing systems, las and rhl, to control numerous virulence factors (including LasB elastase) through two primary autoinducers, 3-oxo-C12-HSL and C4-HSL. Recently a third inducer molecule designated as the Pseudomonas Quinolone Signal (PQS) was discovered. Preliminary results show that PQS is regulated by the las quorum sensing system and that it requires at least Rh1R to inducer lasB. To elucidate the PQS synthetic pathway, g3enes characterize factors controlling PQS expression. To elucidate pathway, genes responsible for anthranilate (a PQS precursor) synthesis will be studied, and a phenotypic, and a phenotypic screen based on LasB production will be used to clone other genes responsible for PQS production. To define the role of PQS in P. aeruginosa virulence, reporter gene fusions will be used to determine how PQS affects the expression of different virulence genes. Finally, to study PQS expression, or PQS bioassay will be used to monitor its production under various conditions. The long term goal of this proposal is to determine the role of PQS in the pathogenesis of P. aeruginosa infections with the hope it will lead to new and effective therapies against aeruginosa.