Development of DHPS as a Bioterrorism Therapeutic Target

DHPS 作为生物恐怖主义治疗目标的发展

• 批准号: 6809822
• 负责人: STEPHEN W WHITE
• 金额: $ 26.4万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6809822
• 关键词: Bacillus anthracis; Francisella tularensis; X ray crystallography; Yersinia pestis; active sites; bacterial genetics; binding sites; bioterrorism /chemical warfare; catalyst; chemical models; combinatorial chemistry; computer simulation; drug design /synthesis /production; drug receptors; enzyme inhibitors; enzyme mechanism; other phosphotransferase; pharmacokinetics; polymerase chain reaction; pteridines; site directed mutagenesis

DESCRIPTION (provided by applicant): Unlike higher animals, folate biosynthesis is an essential bacterial pathway, and it is an attractive target for the development of new antibacterial agents. The sulfa drugs target a key enzyme in the pathway, dihydropteroate synthase (DHPS), but bacterial resistance is making them less potent in clinical therapy. Sulfa drugs mimic the binding of p-arninobenzoic acid (pABA) to DHPS, but the second pterin binding site has yet to be developed in the search for novel inhibitors. This site is buried in the protein core, and mutations that can lead to resistance are less likely to be structurally tolerated than those in the pABA binding site, which comprises flexible loops. A barrier to developing new DHPS inhibitors is our incomplete understanding of the catalytic mechanism. Four structures of the enzyme are available, but the loop regions have not been visualized in their functional conformation. In contrast, the rigid and conserved pterin-binding site has been clearly defined. We propose to design and synthesize transition state analogues of DHPS and other inhibitors that access the pterin binding site, and to iteratively use them to characterize the catalytic mechanism and to generate inhibitor scaffolds for a future drug discovery program. This project is being submitted in the high risk, high impact category under PA-03-080 (biodefense and emerging infectious disease) for three reasons. First, there is no guarantee that useful small molecules will be forthcoming from the project, but the discovery of the exact catalytic mechanism of this enzyme and tight pterin binding scaffolds would be a major advance in pursuing this well validated drug target. Second, we have solved the structure of DHPS from the category A biowarfare agent B. anthracis, and this enzyme, together with those from Y, pestis and F. tularensis will be the focus of this application. Our goal is to design related inhibitors with activity spectra tuned to these three enzymes that could form the basis of biowarfare therapeutics. Third, the pterin-binding pocket of DHPS offers the opportunity of also developing desperately needed broad-spectrum anti-infectives. The project will be a collaboration between a crystallographer at St. Jude Children's Research Hospital and a medicinal chemist at the University of Tennessee Health Science Center. The institutions have complementary programs in infectious diseases with a strong emphasis on studying bioterrorism.

描述（由申请人提供）：与较高的动物不同，叶酸生物合成是必不可少的细菌途径，它是开发新抗菌剂的有吸引力的靶标。 Sulfa药物靶向途径中的关键酶，即二氢蛋白酶合酶（DHP），但细菌耐药性使它们在临床疗法中的有效性降低。 Sulfa药物模仿p-氨基苯甲酸（PABA）与DHP的结合，但是在寻找新型抑制剂时尚未开发第二个翼龙结合位点。该部位埋在蛋白质核心中，与PABA结合位点中的突变相比，可能导致抗性的突变在结构上耐受性较小，PABA结合位点包括柔性环。开发新DHP抑制剂的障碍是我们对催化机制的不完全理解。可以使用四个酶的结构，但是循环区域尚未在其功能构象中可视化。相反，已经明确定义了刚性和保守的翼龙结合位点。我们建议设计和合成DHP的过渡状态类似物和其他访问翼龙结合位点的抑制剂，并迭代地使用它们来表征催化机制，并为未来的药物发现程序生成抑制剂支架。由于三个原因，该项目正在以PA-03-080（Biodefense和新兴传染病）下的高风险，高影响力类别提交。首先，不能保证该项目可以从该项目中获得有用的小分子，但是发现该酶的确切催化机制和紧密的翼龙结合支架将是追求这一经过良好验证的药物靶标的重大进步。其次，我们已经解决了A类生物生物剂B.炭疽病的类别的DHP结构，该酶以及来自Y，Pestis和F. tolarensis的酶将成为该应用的重点。我们的目标是设计相关的抑制剂，该抑制剂调整了这三种酶，这些酶可能构成生物质量治疗的基础。第三，DHPS的翼骨结合口袋提供了开发急需的广谱抗感染物的机会。该项目将是圣裘德儿童研究医院的一位结晶师与田纳西大学健康科学中心的药物学家之间的合作。这些机构在传染病方面具有互补的计划，重点是研究生物恐怖主义。