Sterol/Hopanoid Biosynthesis: An Anti-TB Drug Target

描述（由申请人提供）：耐多药结核病是 世界范围内的流行率增加;因此，更好地了解 结核分枝杆菌的基本生物化学是至关重要的。 对M.结核病基因组表明， 生物合成途径类似于真核生物的甾醇合成。 初步证据表明，M。结核基因组编码酶 与几种真核生物甾醇合成酶具有结构同源性 包括法呢基二磷酸合酶，角鲨烯合酶，角鲨烯环氧酶， 氧化角鲨烯环化酶和羊毛甾醇14 α-脱甲基酶。已经显示 M.结核法呢基二磷酸合酶和羊毛甾醇 14 α-脱甲基酶是真核生物的功能和结构同源物， 内切酶更重要的是，已知的商业抗真菌药物 甾醇合成的抑制剂（特别是氧化角鲨烯环化酶和 羊毛甾醇14 α-脱甲基酶）有效地抑制了M.结核 在文化中。假设M.结核病综合征 类异戊二烯化合物，可能是甾醇或类霍帕烷，这是必不可少的， 有机体的生存能力。因此，这项建议的具体目标是 目的：1）鉴定和表征M. 结核2)分离、酶促表征和测定 M.结核第三章 鉴定和表征氧化角鲨烯环化酶同系物的活性位点。 鉴定了M.结核 和相关酶的表征代表了一种新的方法， 确定以前未被怀疑的抗结核药物靶点。

DESCRIPTION (provided by applicant): Multi-drug resistant tuberculosis is increasing in prevalence worldwide; therefore, a greater understanding of the basic biochemistry of Mycobacterium tuberculosis is of utmost importance. Analysis of the M. tuberculosis genome suggests that there may be a biosynthetic pathway analogous to eukaryotic sterol synthesis in this organism. Preliminary evidence indicates that the M. tuberculosis genome encodes enzymes with structural homology to several eukaryotic sterol synthesis enzymes including farnesyl diphosphate synthase, squalene synthase, squalene epoxidase, oxidosqualene cyclase and lanosterol 14a-demethylase. It has been shown that both the M. tuberculosis farnesyl diphosphate synthase and lanosterol 14a-demethylase are functional as well as structural homologs of the eukaryotic enzymes. More importantly, commercial anti-fungal drugs that are known inhibitors of sterol synthesis (specifically oxidosqualene cyclase and lanosterol 14a-demethylase) effectively inhibit the growth of M. tuberculosis in culture. It is hypothesized that M. tuberculosis synthesizes cyclic isoprenoid compounds, perhaps sterols or hopanoids, which are essential to the viability of the organism. Therefore, the specific aims of this proposal are to: 1) identify and characterize cyclic isoprenoid compounds in M. tuberculosis. 2) isolate, enzymatically characterize and determine the essentiality of the sterol synthesis homologs expressed by M. tuberculosis. 3) identify and characterize the active site of the oxidosqualene cyclase homolog. The identification of a sterol/hopanoid biosynthetic pathway in M. tuberculosis and characterization of relevant enzymes represents a novel approach to the identification of previously unsuspected antituberculosis drug targets.