Molecular Analysis of Bacterial Adaptive Response to Host Reactive Species

描述(由申请人提供)： 感染性腹泻是由多种病毒、寄生虫、真菌和沙门氏菌等细菌引起的一种复杂综合征。沙门氏菌病本身包括一系列临床疾病，从每年导致约60万人死亡的严重疾病肠热病，到每年影响100多万美国人的非伤寒人畜共患感染，其中包括现役军人和退伍军人。沙门氏菌和医学上重要的革兰氏阴性杆菌的治疗往往因病原菌对临床使用的抗生素的耐药性增加而变得复杂。外排泵、修饰酶和改变的靶标增强了细菌对抗生素的耐药性。此外，细菌细胞所使用的代谢途径和机体对环境压力的适应性反应在很大程度上影响了抗生素治疗的有效性。我们实验室和其他实验室最近的研究表明，巨噬细胞内源性或先天反应产生的一氧化氮在多种革兰氏阳性和阴性微生物中引起抗生素耐受。一氧化氮引起的保护性反应似乎与这种双原子自由基引发抗氧化反应的能力有关。在他的申请中提出的初步数据已经确定，Dks A球状结构域中的锌指是氧化和亚硝化应激的骨骼传感器。我们推测，Dks A锌指对活性物质的感知促进了抗氧化剂和抗亚硝化性防御、抗生素耐药性和沙门氏菌的致病性。目的1研究DksA锌指介导氧化和亚硝化应激反应的分子机制。目标2和3将确定Dks A调节的严格反应和半胱氨酸生物合成如何促进沙门氏菌毒力、抗氧化防御和抗生素耐受性。这些研究将为沙门氏菌的抗氧化剂和抗亚硝化性防御提供深刻的见解，这对细胞内生存和毒力至关重要。这项研究还将有助于合理开发未来的预防和治疗方法，用于治疗各种革兰氏阴性细菌，这些细菌在全球范围内导致高发病率和死亡率，包括退伍军人和退伍军人医院的患者。

DESCRIPTION (provided by applicant): Infectious diarrhea is a complex syndrome caused by many viruses, parasites, fungi and bacteria such as Salmonella. Salmonellosis itself encompasses a spectrum of clinical diseases that range from enteric fever, a serious condition that kills about 600,000 people a year, to non-typhoidal zoonotic infections that affect more than a million Americans annually, including active military servicemen and the veteran population. Treatment of Salmonella and medically important Gram- negative rods is often complicated by the increasing resistance of pathogenic bacteria to the antibiotics used in the clinic. Efflux pumps, modifying enzymes, and altered targets enhance bacterial resistance to antibiotics. In addition, the effectiveness of antibiotic therapy is greatly influenced by the metabolic pathways used by the bacterial cell and by the adaptive responses of the organism to environmental stresses. Recent investigations from our laboratory and others have shown that nitric oxide produced endogenously or in the innate response of macrophages elicits antibiotic tolerance in a variety of Gram-positive and -negative microorganisms. The protective response elicited by nitric oxide appears to be associated the ability of this diatomic radical to elicit antioxidative responses. Preliminary data presented in his application has identified the zinc finger in the globular domain of DksA as a bone fide sensor of oxidative and nitrosative stress. We hypothesize that sensing of reactive species by the DksA zinc finger promotes antioxidant and antinitrosative defenses, antibiotic resistance and the pathogenicity of Salmonella. Aim 1 will determine the molecular mechanisms that mediate sensing of oxidative and nitrosative stress by the DksA zinc finger. Aims 2 and 3 will identify how DksA-regulated stringent response and cysteine biosynthesis foster Salmonella virulence, antioxidant defenses and antibiotic tolerance. These investigations will provide profound insights into the antioxidant and antinitrosative defenses of Salmonella that are critical for intracellula survival and virulence. This research will also help in the rational development of future prophylactic and therapeutic approaches for the treatment of a variety of Gram-negative, often antibiotic resistant, bacteria that cause high rates of morbidity and mortality in people around the globe, including veterans and patients in VA hospitals.