Regulation of Fatty Acid Biosynthesis and Degradation in Pseudomonas aeruginosa

描述(由申请人提供)：铜绿假单胞菌在肺内复制到非常高的细胞密度(HCD)，使细菌能够群体感应并分泌大量毒力毒素，导致囊性纤维化(CF)患者发生严重和慢性肺部感染。这些过程的中心是脂肪酸生物合成(FAB)和脂肪酸降解(FAD)。Fab负责铜绿假单胞菌中两个控制毒力的酰化高丝氨酸内酯(AHL)分子的合成，Fad作为营养源参与囊性纤维化肺中磷脂酰胆碱(PC)的代谢。因此，Fab-和Fad-通路在铜绿假单胞菌的发病机制中都是至关重要的，它们允许HCD复制并产生两个AHL群体感应分子。对这两条途径的监管在很大程度上是未知的。根据我们的初步数据，工作假设是在铜绿假单胞菌中，通过上调一条途径和下调另一条途径，Fab和Fad是协同反向调节的。基于这一工作假说，我们建议：i)鉴定和表征控制FabAB和对PC代谢重要的FadBA操纵子之一的调控因子；ii)进行微阵列实验，以建立在相同调节子中调控的其他FAD或Fab相关基因。鉴定这种在基因水平上控制这两条途径的调节蛋白，是理解生理学和控制对铜绿假单胞菌致病至关重要的过程的关键。此外，它还将有助于在同一调控子中发现与肺营养物质利用相关的其他FAD基因。铜绿假单胞菌是一种新出现和再次出现的感染性病原体，对公共卫生造成严重负担，因为它是医院获得性肺炎的主要罪魁祸首，并导致数十万CF患者(主要是儿童)长期痛苦和高死亡率。因此，预计这些研究将有助于改进治疗的创新方法，以延长患有衰弱的慢性肺部感染的CF患者的生命。

DESCRIPTION (provided by applicant): Replication of Pseudomonas aeruginosa to very high-cell-density (HCD) in the lung allows the bacteria to quorum-sense and secrete numerous virulence toxins, causing severe and chronic lung infections in cystic fibrosis (CF) patients. Central to these processes are Fatty acid biosythesis (Fab) and fatty acid degradation (Fad). Fab is responsible for the syntheses of two virulence-controlling acylated-homoserine- lactone (AHL) molecules in P. aeruginosa, and Fad contributes to phosphatidylcholine (PC) metabolism in the Cystic Fibrosis lung as a nutrient source. Hence, both Fab- and Fad-pathways are critical for the pathogenesis of P. aeruginosa by allowing HCD replication and producing two AHL quorum-sensing molecules. Regulation of both pathways is largely unknown. The working hypothesis, based on our preliminary data, is that Fab and Fad are coordinately inverse regulated in P. aeruginosa, by up-regulating one pathway and down-regulating the other. Based on this working hypothesis, we propose to: i) identify and characterize the regulator that controls fabAB and one of the fadBA-operons important for PC metabolism and ii) perform microarray experiments to establish other Fad or Fab related genes that are regulated in the same regulon. Identifying this regulatory protein that controls both pathways, at the genetic level, is the key to understanding physiology and control of processes that are critical for the pathogenesis of P. aeruginosa. In addition, it will contribute to the identification of other fad-genes in the same regulon that could contribute to nutrient utilization in the CF lung. P. aeruginosa is an emerging and re-emerging infectious agent that causes serious burdens to public health, because it is a major culprit of hospital-acquired pneumonia and causes prolonged suffering and high mortality to hundreds of thousands of people (mostly children) with CF. Hence, it is expected that these studies will contribute to innovative approaches for improved treatment to extend the lives of CF patients with debilitating chronic lung infections.