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）：与高等动物不同，叶酸生物合成是必不可少的细菌途径，它是开发新型抗菌剂的一个有吸引力的目标。磺胺类药物靶向该途径中的一种关键酶——二氢蝶呤合成酶（DHPS），但细菌耐药性使它们在临床治疗中的作用减弱。磺胺类药物模拟对氨基苯甲酸（pABA）与DHPS的结合，但在寻找新的抑制剂时，还没有开发出第二种蝶呤结合位点。该位点隐藏在蛋白质核心中，与pABA结合位点相比，可能导致耐药性的突变在结构上不太可能耐受，pABA结合位点由柔性环组成。开发新的DHPS抑制剂的一个障碍是我们对催化机制的不完整理解。酶的四种结构是可用的，但环区还没有可视化的功能构象。相比之下，刚性和保守的pterin结合位点已经明确定义。我们建议设计和合成DHPS和其他进入蝶呤结合位点的抑制剂的过渡态类似物，并迭代地使用它们来表征催化机制，并为未来的药物发现计划生成抑制剂支架。本项目被列入PA-03-080（生物防御和新发传染病）下的高风险、高影响类别，原因有三。首先，不能保证从这个项目中会得到有用的小分子，但是发现这种酶的确切催化机制和紧密的蝶呤结合支架将是追求这种良好验证的药物靶点的重大进展。其次，我们已经从A类生物战剂炭疽杆菌中解出了DHPS的结构，该酶将与Y、鼠疫菌和土拉菌的DHPS一起成为本次应用的重点。我们的目标是设计与这三种酶的活性谱相匹配的相关抑制剂，以形成生物战治疗的基础。第三，DHPS的蝶呤结合口袋也提供了开发迫切需要的广谱抗感染药物的机会。该项目将由圣裘德儿童研究医院的晶体学家和田纳西大学健康科学中心的药物化学家合作完成。这些机构在传染病方面有补充项目，重点是研究生物恐怖主义。