DRUGS DIRECTED AGAINST ISOPRENOID BIOSYNTHESIS

多药结核病在世界范围内日益流行，寻找新的抗结核药物势在必行。更好地了解结核分枝杆菌的基本生物化学将极大地促进这一过程。这项建议的总体目标是确定与结核分枝杆菌细胞壁合成有关的药物靶点，确定所涉及的酶的特征，并确定用于药物开发的先导化合物。本项目(3)侧重于参与类异戊二烯生物合成的酶所起的作用。异戊二烯的生物合成可以被认为是细胞壁合成的最早步骤之一，使其成为理想的潜在药物靶点。异戊二烯类化合物，如聚戊烯基磷酸酯、孟喹酮，可能还有类己二烯类化合物，在分枝杆菌新陈代谢中起着至关重要的作用，在某些情况下甚至是必不可少的。观察到结核分枝杆菌对局部抗生素杆菌肽敏感，这种抗生素抑制类异戊二烯的生物合成，表明类异戊二烯化合物的合成是结核分枝杆菌生存所必需的。许多细菌类异戊二烯在结构上与真核生物中发现的不同，但对结核分枝杆菌中这些化合物的生物合成知之甚少。最初的假设是原核生物使用与真核生物相同的生物合成途径来合成类异戊二烯，这一假设最近被证明是正确的。我们相信，对参与独特和必要的生物合成途径的酶的鉴定和表征将导致治疗结核病的新药的开发。考虑到这一点，我们开发了以下项目，其中我们将尝试：1)使用中高通量实验，鉴定抑制1-脱氧木糖-5-磷酸合成酶(DXS)的化合物，DXS是细菌类异戊二烯生物合成所必需的酶，在哺乳动物中找不到。2)鉴定分枝杆菌特有的类异戊二烯生物合成途径的部分。

The prevalence of multi-drug tuberculosis is increasing worldwide making the search for new anti-tuberculosis drugs imperative. A greater understanding of the basic biochemistry of M. tuberculosis will greatly facilitate this process. The overall objective of this proposal is to identify drug targets relating to cell wall synthesis in M. tuberculosis, characterize the enzymes involved and identify lead compounds for drug development. This project (3) focuses on the role played by the enzymes involved in isoprenoid biosynthesis. Isoprenoid biosynthesis can be considered one of the earliest steps in cell wall synthesis making it an ideal potential drug target. Isoprenoid compounds such as polyprenyl phosphate, menaquinone and possibly hopanoids play crucial and in some cases essential roles in mycobacterial metabolism. The observation that M. tuberculosis is susceptible to the topical antibiotic bacitracin, which inhibits isoprenoid biosynthesis demonstrates that the synthesis of the isoprenoid compounds is required for the survival of M. tuberculosis. Many bacterial isoprenoids are structurally distinct from those found in eukaryotes yet little is known about the biosynthesis of these compounds in M. tuberculosis. It was originally assumed that prokaryotes use the same biosynthetic pathways as eukaryotes for the synthesis of isoprenoids This assumption has recently been shown to be correct. We believe that identification and characterization of enzymes involved in unique and essential biosynthetic pathways will lead to the development of novel drugs for the treatment of tuberculosis. With that in mind, we have developed the following project in which we will attempt to: 1) identify compounds that inhibit 1-deoxyxylulose-5-phosphate synthase (DXS), an enzyme essential for bacterial isoprenoid biosynthesis that is not found in mammals, using a medium to high throughput assay. 2) Characterize the portions of the isoprenoid biosynthetic pathway that are unique to mycobacteria.