NOVEL CLASS OF PHOSPHOLIPASES--MOLECULAR PATHOGENESIS

新一类磷脂酶——分子发病机制

• 批准号: 6185028
• 负责人: Michael L. Vasil
• 金额: $ 34.24万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-06-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6185028
• 关键词: Pseudomonas aeruginosa; betaine compound; cystic fibrosis; cytolysis; enzyme activity; fusion gene; gene mutation; host organism interaction; laboratory mouse; laboratory rabbit; laboratory rat; molecular cloning; molecular pathology; monoclonal antibody; opportunistic infections; osmotic pressure; phosphatidylcholines; phospholipase C; posttranslational modifications; protein structure function; pulmonary surfactants; respiratory infections; site directed mutagenesis; virulence

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.

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。 最多 囊性纤维化（CF）患者在很小的时候就被定植为 这种微生物和大多数 CF 患者最终死于慢性肺病 铜绿假单胞菌感染。 非凡的原因 与其他患者相比，铜绿假单胞菌在这些患者中的致病性 例如，假单胞菌尚不清楚。 很有可能的是 铜绿假单胞菌产生的多种毒力决定子有助于 其致病潜力。 不幸的是，这些的具体贡献 单独或组合的因素，甚至是最简单的 P 类型。 铜绿假单胞菌感染尚未阐明。 在过去的几年里 使用分子、生化和遗传学方法的研究已经开始 阐明结构与功能的关系和机制 毒力决定因素的调节。 这项研究针对的是 了解磷脂酶 C (PLC) 生产在 铜绿假单胞菌感染的发病机制。 PLC已得到认可 近年来作为真核和原核生物中的关键酶 生物学。 在真核生物中，它是重要的第二信使 细胞过程，特别是特定和 非特异性免疫机制。 在原核生物中已经存在 人们对 PLC 作为关键毒力决定因素的兴趣重新燃起， 在革兰氏阴性和革兰氏阳性感染中。 铜绿假单胞菌产生 两种不同的 PLC 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。 1 个 PLC 具有溶细胞性 (PLC-H) 对人红细胞和中性粒细胞有影响，而另一个对人红细胞和中性粒细胞没有影响 (PLC-N) 裂解此类细胞。 这些和其他特征表明 PLC活性与溶细胞作用之间的结构-功能关系 本研究项目将调查的活动。 一个更多 完全理解两者的结构与功能关系 PLC 将有助于更好地了解它们在发病机制中的作用 铜绿假单胞菌，并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 提出该作用产生的底物产物的衍生物 两种 PLC 对磷脂酰胆碱（肺中主要必需脂质）的影响 表面活性剂，对铜绿假单胞菌的发病机制有显着贡献 感染。 我们假设其中一些衍生物特别 与该微生物在 CF 患者肺部的存活有关。 我们将研究一类称为渗透保护剂的化合物如何 包括甘氨酸甜菜碱，能够诱导两种 PLC 的合成 铜绿假单胞菌。 该化合物源自底物之一 两种 PLC 的产品，可以为该生物体的生存提供条件 高渗透环境，例如在 CF 患者的肺部或在 泌尿道。 我们建议了解这种不寻常的监管 这个过程可能会导致新药物的发现，这至少可能 缓和铜绿假单胞菌的致病潜力，如果不直接影响 它能够在 CF 患者的肺部持续存在，或者在 泌尿道的高渗透环境。