P AERUGINOSA PHOSPHOLIPASE C--MOLECULAR PATHOGENESIS

摘要铜绿假单胞菌是一种重要的条件致病菌。 关于其引起的感染的发病率和死亡率。多数 囊性纤维化(CF)患者在很小的时候就被定居在 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。非同寻常的原因 铜绿假单胞菌在这些患者中的致病性与其他 以假单胞菌为例，目前还不清楚。很有可能是 铜绿假单胞菌产生的无数毒力决定因素有助于 它的致病潜能。不幸的是，这些产品的确切贡献 因素，单独的或组合的，即使是最简单的P。 铜绿假单胞菌感染尚未阐明。在过去几年里 使用分子、生物化学和遗传学方法的研究已经开始 阐明其结构与功能的关系及机制 毒力决定因素的调控。这项研究是针对 了解磷脂酶C(PLC)的产生在生物合成中的作用 铜绿假单胞菌感染的发病机制。PLC在以下方面得到认可 近年来在真核和原核生物中都是一种关键酶 生物学。在真核生物中，它是关键的第二信使 细胞过程，特别是在特定的和 非特异性免疫机制。在原核生物中，有一种 重新引起人们对PLC作为关键毒力决定因素的兴趣，两者 革兰氏阴性和革兰氏阳性感染。铜绿假单胞菌产生 两个不同的PLC可能在发病机制中发挥重要作用 肺部感染，以及其他类型的感染。一种PLC是细胞溶解的 (PLC-H)在人红细胞和中性粒细胞上，而另一种不是 (PLC-N)裂解这些细胞。这些特征和其他特征表明 PLC活性与细胞溶解的结构-功能关系 将在本研究项目中调查的活动。A更多 对两者的结构-功能关系有完整的理解 PLC将有助于更好地了解它们在发病机制中的作用 可能导致对铜绿假单胞菌的治疗干预。 以前没有考虑到的铜绿假单胞菌肺部感染。我们也 提出了衍生品对底物产物产生的作用 两种细胞对肺中主要必需脂质磷脂酰胆碱的影响 表面活性物质在铜绿假单胞菌致病中的重要作用 感染。我们假设其中一些衍生品特别是 与这种微生物在CF患者的肺中的生存有关。 我们将研究一类称为渗透保护剂的化合物是如何 包括甘氨酸甜菜碱，能够诱导这两种PLC的合成 在铜绿假单胞菌。这种化合物是从底物的一种衍生而来的 这两种PLC的产物，可以为这种有机体在 高渗透环境，如在慢性阻塞性肺疾病患者的肺部或在 尿路。我们建议理解这一不同寻常的监管 这一过程可能会导致发现新的制剂，至少可能 缓和铜绿假单胞菌的致病潜能，如果不直接影响 它在CF患者的肺中持续存在的能力，或在 尿路的高渗透环境。

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.