Structure and Inhibition of the Conjugative DNA Relaxase-Helicase

描述（由申请人提供）：耐抗生素细菌感染每年杀死更多的美国人比结肠癌，前列腺癌和卵巢癌的总和。接合DNA转移产生了大多数感染人类的抗生素抗性细菌菌株。我们最近已经表明，松弛酶必不可少的DNA转移过程中，可以抑制纳摩尔效力使用各种小分子，包括一些骨质疏松症药物。松弛酶抑制剂阻止DNA转移并选择性地杀死抗生素耐药细菌。接合F质粒的松弛酶是大型多功能TraI蛋白的一部分，该蛋白还含有高效解旋酶和推定的蛋白结合C-末端结构域。TraI的松弛酶、解旋酶和C-末端区域对于接合DNA转移都是必需的。该应用程序的重点是扩展我们的初步结构和化学生物学研究，目的是了解DNA转移的分子基础，并开发能够杀死抗生素耐药细菌的小分子。该项目将实现四个具体目标：1。阐明一系列松弛酶抑制剂复合物的晶体结构。2.发现和合成新的松弛酶抑制剂，并测试它们对接合和细菌存活的影响。3.揭示TraI C端结构域在接合转移中的作用。4.检查TraI接合解旋酶区域的结构、功能和抑制。这些研究的结果将为发现的第一个DNA操纵系统之一提供详细的机械见解。此外，由于保守的松弛酶存在于一系列致病微生物中，我们的研究结果可能提供一种新的方法来靶向最危险的感染性细菌-那些具有抗生素抗性并能够将其抗性传播到邻近细胞的细菌。公共卫生相关性：接合DNA转移是抗生素抗性基因在细菌群体中传播的主要途径，由DNA松弛酶和解旋酶启动和驱动。我们最近已经表明，接合松弛酶可以抑制纳摩尔效力，这种抑制阻止DNA接合，并选择性地杀死抗生素耐药细菌。该项目将扩展我们的初步结构和化学生物学发现，目的是了解DNA转移的分子基础，并开发有效杀死抗生素耐药细菌的药物。

DESCRIPTION (provided by applicant): Antibiotic resistant bacterial infections kill more Americans each year than colon, prostate and ovarian cancer combined. Conjugative DNA transfer generates most of the antibiotic resistant strains of bacteria that infect humans. We have recently shown that the relaxase enzyme essential to this DNA transfer process can be inhibited with nanomolar efficacy using a variety of small molecules, including some osteoporosis drugs. Relaxase inhibition prevents DNA transfer and selectively kills antibiotic resistant bacteria. The relaxase of the conjugative F plasmid is part of the large multifunctional TraI protein that also contains highly efficient helicase and putative protein-binding C-terminal domains. The relaxase, helicase and C-terminal regions of TraI are all essential for conjugative DNA transfer. This application focuses on extending our preliminary structural and chemical biology studies with the goals of understanding the molecular basis of DNA transfer and developing small molecules capable of killing antibiotic resistant bacteria. This project will accomplish four specific aims: 1. Elucidate crystal structures of a range of relaxase-inhibitor complexes. 2. Discover and synthesize new relaxase inhibitors and test their impact on conjugation and bacterial survival. 3. Unravel the role the TraI C-terminal domain plays in conjugative transfer. 4. Examine the structure, function and inhibition of the TraI conjugative helicase region. Results from these studies will provide detailed mechanistic insights into one of the first DNA manipulation systems discovered. In addition, because conserved relaxases are present in a range of pathogenic microbes, our results may provide a novel method to target the most dangerous infectious bacteria - those that are antibiotic resistant and are capable of spreading their resistance to neighboring cells. PUBLIC HEALTH RELEVANCE: Conjugative DNA transfer, the primary route by which antibiotic resistance genes spread through bacterial populations, is initiated and driven by DNA relaxase and helicase enzymes. We have recently shown that conjugative relaxases can be inhibited with nanomolar efficacy, and that this inhibition prevents DNA conjugation and selectively kills antibiotic resistant bacteria. This project will extend our preliminary structural and chemical biology discoveries with the goal of understanding the molecular basis of DNA transfer and developing drugs that potently kill antibiotic resistant bacteria.