Sterol/Hopanoid Biosynthesis: An Anti-TB Drug Target

描述(申请人提供)：耐多药结核病是 在世界范围内流行；因此，更好地了解 结核分枝杆菌的基础生物化学是至关重要的。 对结核分枝杆菌基因组的分析表明，可能存在一个 生物合成途径，类似于真核生物中的甾醇合成。 初步证据表明，结核分枝杆菌基因组编码酶。 与几种真核生物甾醇合成酶结构同源 包括法尼基二磷酸合成酶、角鲨烯合成酶、角鲨烯环氧酶、 氧化橙烯环化酶和羊毛甾醇14a-脱甲基酶。事实证明， 结核分枝杆菌法尼基二磷酸合成酶和羊毛甾醇 14A-去甲基酶是真核生物的功能和结构上的同源物 酵素。更重要的是，已知的商业抗真菌药物 甾醇合成的抑制剂(特别是氧化橙烯环化酶和 羊毛甾醇14a-脱甲基酶)有效抑制结核分枝杆菌的生长 在文化上。假设结核分枝杆菌合成环状 异戊二烯类化合物，可能是类固醇或类胡萝卜素，它们对 生物体的生存能力。因此，这项建议的具体目标是 目的：1)鉴定和鉴定环异戊二烯类化合物。 肺结核。2)分离、酶学鉴定及鉴定 结核分枝杆菌表达的类固醇合成同系物的重要性。3) 鉴定和鉴定氧化橙烯环化酶同系物的活性部位。 结核分枝杆菌类固醇/类胡萝卜素生物合成途径的鉴定 而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.