Mechanisms of Resistance in Gram-Negative Bacteria

囊性纤维化(CF)患者发生慢性呼吸道感染 机会革兰氏阴性杆菌铜绿假单胞菌。呼吸道炎症 这些感染的特征是中性粒细胞渗入而不是细菌破坏。它 已有研究表明，从囊性纤维化患者中分离的假单胞菌具有特异性， 它们的类脂A结构中的毒力相关修饰。这些修改，即 包括与棕榈酸酯和4-氨基阿拉伯糖取代，是造成抗性的原因 对天然免疫的重要组成部分阳离子抗菌肽(CAMP) 还有多粘菌素，一种阵营抗生素。负责4-氨基丁酸生物合成的酶 氨基阿拉伯糖-脂A聚集在最近被重新命名为ArnBCADTEF的操纵子中。 这些基因中的任何一个突变都会取消4-氨基阿拉伯糖加成到脂类A和 对营地的抵抗。基于我们之前对Arna所做的结构和生化工作 我们已经开发了一种选择性抑制Arna的策略。在这项提案中，我们还 靶ARND，一种假想的脱甲酰基酶，对4-甲基-4-酮的生物合成是必不可少的 氨基阿拉伯糖-脂类A，用于生化和结构表征。禁止任何 这些酶的使用将消除铜绿假单胞菌对抗菌素的耐药性 多肽，从而大大增强宿主对慢性疾病的免疫反应 感染假单胞菌。既要提高生活质量，又要提高生存年龄 Cf患者必须制定新的策略来管理他们的肺 感染。鉴于这些感染的慢性性质，预防或废除 抵抗是一个根本问题。这项提案侧重于描述 介导对营地的耐药性的细菌靶标。

Patients with Cystic Fibrosis (CF) develop chronic airway infections with the opportunistic gram negative bacteria Pseudomonas aeruginosa. Airway inflammation and neutrophilic infiltration without bacterial destruction characterize these infections. It has been shown that Pseudomonas isolated from Cystic Fibrosis patients have specific, virulence-associated modifications in their lipid A structure. These modifications, which include substitutions with palmitate and 4-aminoarabinose, are responsible for resistance to cationic antimicrobial peptides (CAMPs), an important component of innate immunity and Polymyxin, a CAMP antibiotic. The enzymes responsible for the biosynthesis of 4- aminoarabinose-lipid A are clustered in an operon recently renamed to ArnBCADTEF. Mutation of any of these genes abolishes 4-aminoarabinose addition to lipid A and resistance to CAMPs. Based on our previous structural and biochemical work with ArnA we have developed a strategy for selective inhibition ArnA . In this proposal we also target ArnD, a hypothetical deformylase essential for the biosynthesis of 4- aminoarabinose-lipid A, for biochemical and structural characterization. Inhibition of any of these enzymes would abolish Pseudomonas aeruginosa resistance to antimicrobial peptides, therefore greatly enhancing the host immune response against chronic infections with Pseudomonas. To improve both the quality of life and the survival age of CF patients it is crucial that new strategies are developed to manage their pulmonary infections. Given the chronic nature of these infections preventing or abolishing resistance is a fundamental problem. This proposal focuses on the characterization of bacterial targets that mediate resistance to CAMPs.