Molecular Analysis of Bacterial Adaptive Response to Host Reactive Species

感染性腹泻每年折磨着10亿人，占人类死亡总数的4%。许多 2,500种非伤寒沙门氏菌血清型是感染性腹泻的常见原因， 普通民众、现役军人和退伍军人。与沙门氏菌一样， 对抗生素有抗药性的细菌数量在稳步增加。革兰阴性杆菌的耐药性是 成为一个几乎没有治疗药物的临床问题。未来 针对耐药细菌的预防和治疗方法将大大受益于更深入的研究， 了解细菌致病的分子机制。本课题组的研究， 许多其他研究表明，RNA聚合酶调节蛋白DksA在细胞凋亡中起着关键作用。 多种革兰氏阴性杆菌，包括沙门氏菌，志贺氏菌，弯曲杆菌， 嗜血杆菌，假单胞菌和弧菌。我们已经发现， DksA锌指蛋白不仅在沙门氏菌致病机制中起重要作用，而且也是一种新型的沙门氏菌致病传感器。 氧化应激这项拟议的研究将检验DksA锌指形成稳定的锌指的假设。 亚磺酸对低水平氧化应激的反应，从而激活转录。上级 然而，DnaJ分子伴侣的氧化还原酶活性催化二硫键 DksA锌指的形成，一种抑制基因转录的氧化还原状态。该模型高度 创新，因为它将DksA定义为具有离散调节输出的硫醇多重体， 锌指中半胱氨酸残基的氧化程度。我们的调查将有助于更深层次的 了解细菌致病的关键步骤，也将有助于合理开发 抗生素对遗传多样性革兰氏阴性杆菌。基于我们对 DksA，我们已经确定了一种药物，其靶向于这种蛋白的卷曲螺旋结构域尖端的口袋。 RNA聚合酶调节蛋白。该新化合物具有优异的抗生素活性， 沙门氏菌和杆菌这项研究将有助于开发和测试新的抗生素， DksA中的保守口袋。我们的研究将有助于未来疗法的合理发展 针对各种革兰氏阴性菌，通常是抗生素耐药菌，导致高发病率 以及退伍军人及其家属的死亡率。

Infectious diarrhea afflicts a billion people a year and is responsible for 4% of all human deaths. Many of the 2,500 serovars of nontyphoidal Salmonella enterica are common causes of infectious diarrhea in the general population, active military servicemen and veterans. As is the case for Salmonella, the number of bacteria resistant to antibiotics is steadily increasing. Antibiotic resistance in Gram-negative bacilli is becoming a clinical problem of epic proportions with few therapeutic agents in the horizon. Future prophylactic and therapeutic approaches against drug resistant bacteria will greatly benefit from a deeper understanding of the molecular mechanisms of bacterial pathogenesis. The research of our group and many others has shown critical roles for the RNA polymerase regulatory protein DksA in the pathogenesis of multiple Gram-negative bacilli, including Salmonella, Shigella, Campylobacter, Haemophilus, Pseudomonas, and Vibrio. We have discovered that conserved cysteine residues in the DksA zinc finger are not only important for Salmonella pathogenesis but also represent a novel sensor of oxidative stress. The proposed research will test the hypothesis that the DksA zinc finger forms a stable sulfenic acid in response to low levels of oxidative stress, thereby activating transcription. At higher levels of oxidative stress, however, the oxidoreductase activity of the DnaJ chaperone catalyzes disulfide bond formation in DksA zinc finger, a redox state that represses gene transcription. This model is highly innovative because it defines DksA as a thiol multiplex with discrete regulatory outputs according to degree of oxidation of cysteine residues in the zinc finger. Our investigations will contribute to a deeper understanding of critical steps in bacterial pathogenesis and will also help the rational development of antibiotics against phylogenetically diverse Gram-negative bacilli. Based on our basic knowledge of DksA, we have already identified a drug that targets a pocket at the tip of the coiled-coil domain of this RNA polymerase regulatory protein. This novel compound has excellent antibiotic activity against Salmonella and E. coli. The proposed research will help develop and test novel antibiotics against conserved pockets in DksA. Our investigations will aid with the rational development of future therapies against a variety of Gram-negative, often antibiotic resistant, bacteria that cause high rates of morbidity and mortality in veterans and their families.