P AERUGINOSA PHOSPHOLIPASE C--MOLECULAR PATHOGENESIS

铜绿假单胞菌是一种重要的条件致病菌， 就其引起的感染的发病率和死亡率而言。 最 囊性纤维化（CF）患者在幼年时定植有 这种生物体和大多数CF患者最终死于慢性肺 铜绿假单胞菌感染。 之所以会有如此非凡的成就 铜绿假单胞菌在这些患者中的致病性，与其他 例如假单胞菌，就不清楚了。 极有可能 铜绿假单胞菌产生的无数毒力决定因子有助于 其致病潜力。 不幸的是，这些人的贡献 因素，单独或组合，即使是最简单的P。 铜绿假单胞菌感染尚未阐明。 过去几年 利用分子、生物化学和遗传学方法的研究已经开始， 阐明结构-功能关系和机制 毒力决定因子的调节。 这项研究旨在 了解磷脂酶C（PLC）的生产在 铜绿假单胞菌感染的发病机制。 PLC已成为公认的 近年来作为一个关键酶在真核生物和原核生物 生物学 在真核生物中，它是一种重要的第二信使， 细胞过程，特别是在特定的功能， 非特异性免疫机制 在原核生物中， PLC作为一个关键的毒力决定因素的兴趣的复苏， 革兰氏阴性和革兰氏阳性感染。 铜绿假单胞菌产生 两种不同的PLC可能在发病机制中发挥重要作用， 以及其他类型的感染。 一个PLC是溶细胞的 （PLC-H）对人红细胞和中性粒细胞，而另一个不是 （PLC-N）裂解这些类型的细胞。 这些和其他特征表明 PLC活性与细胞溶解性构效关系 将在本研究项目中进行研究。 一个更 完全理解两者的结构-功能关系 PLC将导致更好地了解其在发病机制中的作用 的铜绿假单胞菌，并可能导致对P. 铜绿假单胞菌肺部感染，以前没有考虑。 我们也 提出由该作用产生的底物产物的衍生物 磷脂酰胆碱，肺中的主要必需脂质 表面活性剂，显着有助于铜绿假单胞菌的发病机制 感染. 我们假设其中一些衍生物特别 与CF患者肺中该生物体的存活相关。 我们将研究如何一类化合物，被称为植物保护剂 包括甘氨酸甜菜碱，能够诱导两种PLC的合成 在铜绿假单胞菌中。 该化合物来源于底物之一， 这两种PLC的产品，可以提供这种生物体的生存， 高渗透环境，例如在CF患者的肺中或在 泌尿道 我们建议，理解这种不寻常的监管 这一过程可能会导致发现新的药物， 缓和铜绿假单胞菌的致病潜力，如果不直接影响 其在CF患者的肺中持续存在的能力，或在 泌尿道的高渗透环境。

Pseudomonas aeruginosa is an important opportunistic pathogen both in terms of the morbidity and mortality of infections it causes. Most patients with cystic fibrosis (CF), are colonized at an early age with this organism and most CF patients ultimately succumb to a chronic lung infection from P. aeruginosa. The reason for the extraordinary pathogenicity of P. aeruginosa in these patients, as compared to other Pseudomonads for example, is not clear. It is highly probable that the myriad of virulence determinants P. aeruginosa produces contributes to its pathogenic potential. Unfortunately, the exact contribution of these factors, alone or in combination, to even the simplest kind of P. aeruginosa infection has not yet been elucidated. In the past few years studies using molecular, biochemical and genetic approaches have begun to elucidate the structure-function relationships and mechanisms of regulation of virulence determinants. This research is directed at understanding the role of phospholipase C (PLC) production in the pathogenesis of P. aeruginosa infections. PLC has become recognized in recent years as a critical enzyme in both eukaryotic and prokaryotic biology. In eukaryotic organisms it is a critical second messenger in cellular processes, particularly in the function of specific and nonspecific immune mechanisms. In prokaryotic organisms there has been a resurgence of interest in PLC as a critical virulence determinant, both in gram negative and gram positive infections. P. aeruginosa produces two distinct PLCs that could play a significant role in the pathogenesis of lung, as well a other kinds of infections. One PLC is cytolytic (PLC-H) on human erythrocytes and neutrophils, while the other is not (PLC-N) lytic to these kind of cells. These and other features suggest structure-functions relationships between PLC activity and cytolytic activity that will be investigated in this research project. A more complete understanding of the structure-function relationships of both PLCs will lead to better understanding of their role in the pathogenesis of P. aeruginosa, and could result in therapeutic interventions for P. aeruginosa lung infections that were not previously considered. We also propose that derivatives of the substrate products produced by the action of both PLCs on phosphatidylcholine, the major essential lipid in lung surfactant, significantly contribute to the pathogenesis of P. aeruginosa infections. We hypothesize that some of these derivatives are especially relevant to the survival of this organism in the lungs of CF patients. We will investigate how a class of compounds, known as osmoprotectants including, glycine betaine, are able to induce the synthesis of both PLCs in P. aeruginosa. This compound, derived from the one of substrate products of both PLCs, can provide for the survival of this organism in a high osmotic environment, such as found in the lungs of CF patients or in the urinary tract. We propose that understanding this unusual regulatory process could lead to the discovery of novel agents which might at least temper the pathogenic potential of P. aeruginosa, if not directly affect its ability to persist in the lungs of CF patients, or survive in the high osmotic environment of the urinary tract.