Bacterial Proteins Containing Novel Iron Sites

含有新铁位点的细菌蛋白质

基本信息

批准号：
7933133
负责人：
DONALD M. KURTZ
金额：
$ 2.26万
依托单位：
UNIVERSITY OF TEXAS SAN ANTONIO
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-30 至 2010-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7933133
关键词：
Active Sites Air Amino Acid Sequence Anaerobic Bacteria Animals Antibiotics Bacteria Bacterial Proteins Campylobacter jejuni Colon Crystallography Desulfovibrio vulgaris Dioxygen Electron Nuclear Double Resonance Electron Transport Electronics Electrons Enzyme Inhibitor Drugs Enzyme Inhibitors Enzymes Freezing Generations Genes Goals Heme Iron Homologous Gene Human Hydrogen Peroxide Infection Investigation Iron Kinetics Knock-out Life Ligands Monitor Movement Nature Nitric Oxide Oral cavity Oxidation-Reduction Oxidoreductase Oxygen Peroxidases Physiologic pulse Porphyromonas gingivalis Reaction Research Research Personnel Resistance Roentgen Rays Role Site Spectrum Analysis Stomach Structure Superoxides Temperature Tertiary Protein Structure Testing Time Treponema denticola X-Ray Crystallography cryogenics design enzyme mechanism foodborne foodborne pathogen in vivo intestinal epithelium macrophage millisecond mutant nitrosative stress novel oral pathogen oxidation pathogen pathogenic bacteria programs research study response superoxide reductase

项目摘要

DESCRIPTION (provided by applicant): The focus of the proposed research is the structure, function and catalytic mechanisms of three non-heme iron enzymes involved in oxidative or nitrosative stress protection in air-sensitive bacteria. All of the enzymes proposed for study reductively scavenge diatomic molecules that are toxic to air-sensitive bacteria at micromolar or lower levels. The enzyme, superoxide reductase (SOR), scavenges superoxide resulting from the bacteria's accidental one-electron reduction of oxygen. The enzyme, rubrerythrin (Rbr), scavenges hydrogen peroxide resulting from accidental two-electron reduction of oxygen. The flavo-diiron enzyme, FprA, scavenges nitric oxide generated both internally and externally, e.g., from symbiotic bacteria or the intestinal epithelium. Hundreds of bacterial species occupy the human colon and oral cavity, and the vast majority are air-sensitive. These enzymes also conceivably protect against the oxidative and nitrosative burst of macrophages, which is the mammalian host's initial response to infection, but very few studies of these enzymes from pathogens have been conducted. The enzymes listed above from two human periodontal pathogens and from a food-borne human gastric pathogen are among those that will be investigated. Since the catalytic reactions of these enzymes occur on microsecond to millisecond time scales at room temperature, experiments are proposed to either rapidly mix and trap the reaction intermediates or to slow down the reactions using cryogenic temperatures. Both approaches should then allow structural and electronic characterizations of these intermediates using various spectroscopies and X-ray crystallography. The goals are to obtain "snapshots" of the reaction progress and to correlate these reaction mechanisms with the protective roles of these enzymes in vivo. Many of the bacteria that contain SOR, Rbr and FprA have become resistant to the available antibiotics. Since homologues of these enzymes have not been found in humans or animals, inhibitors of these enzymes could conceivably be developed into new classes of antibiotics. The detailed understanding of the catalytic mechanisms of these enzymes and their protective roles resulting from the proposed studies will be essential for the intelligent design of such antibiotics.

描述（由申请人提供）：拟议研究的重点是三种参与空气敏感细菌中氧化或硝化应力保护的三种非血红素铁酶的结构，功能和催化机制。提出的所有用于研究的酶还原性清除双原子分子，这些分子在微摩尔或较低水平上对空气敏感细菌有毒。酶，超氧化物还原酶（SOR），由细菌意外单电子还原氧引起的超氧化物清除。酶，rubrerythrin（RBR），由于意外的两电子还原的氧气减少而导致的过氧化氢。 Flavo-Diiron酶，FPRA，清除一氧化氮在内部和外部产生，例如从共生细菌或肠上皮产生。数百种细菌占据了人类结肠和口腔，绝大多数物种对空气敏感。这些酶还可以想象，可以预防巨噬细胞的氧化性和硝化剂爆发，这是哺乳动物宿主对感染的初始反应，但是对这些酶进行了从病原体进行的这些酶的研究很少。上面从两种人类牙周病原体和食物传播的人类胃病原体中列出的酶是将要研究的酶。由于这些酶的催化反应发生在室温下的微秒至毫秒时尺度上，因此提出了实验以快速混合并捕获反应中间体或使用低温温度减慢反应。然后，两种方法都应使用各种光谱和X射线晶体学对这些中间体进行结构和电子表征。目标是获得反应进展的“快照”，并将这些反应机理与这些酶在体内的保护作用相关联。许多含有SOR，RBR和FPRA的细菌已经对可用的抗生素具有抗药性。由于这些酶的同源物尚未在人类或动物中发现，因此可以想象可以想到这些酶的抑制剂已发展为新的抗生素类。对这些酶的催化机制及其由拟议研究产生的保护作用的详细理解对于这种抗生素的智能设计至关重要。