Structural Basis for Isoprenoid Biosynthesis

描述：（由申请人提供）本研究的长期目标 计划是了解类异戊二烯的结构基础 生物合成的细菌和寄生虫，这将作为基础， 新型抗菌剂和抗疟剂的设计。在 特别是，这项建议的一个主要目的是了解结构和 控制类异戊二烯前体生物合成的机制特征 异戊烯基二磷酸（IPP）和异构体化合物二甲基烯丙基 二磷酸（DMAPP），其由包含甲羟戊酸非依赖性 通路此外，还对近年来出现的一种新的 描述的和新的IPP异构酶，其在机理和结构上不同 将进行从先前描述的IPP异构酶。2型IPP 异构酶，不像研究充分的1型酶，依赖于黄素 Monopoltide和NADPH的活性。值得注意的是，这种类型2类IPP 异构酶存在于几种革兰氏阳性细菌中， 金黄色葡萄球菌表明，它将作为一个有效的目标，新的 抗葡萄球菌药物最后，细菌形式的结构， 将从大肠杆菌获得的酶法呢基二磷酸合酶， 测定IPP和DMAPP是类异戊二烯的基本结构单元， 所有生物体，是构建许多生物体的必需代谢物。 高级萜类化合物。最近的独立研究表明， 一种新的，不依赖甲羟戊酸的IPP合成途径，称为 1-脱氧-D-木酮糖5-磷酸/ 2-C-甲基-D-β-4-磷酸（DXP/MEP） 通路后一种甲羟戊酸盐非依赖性途径利用丙酮酸盐， 甘油醛3-磷酸作为生产IPP的起始材料。的 DXPIMEP途径发生在多种真细菌中，包括几种 病原性物种，如结核分枝杆菌，藻类， 在恶性疟原虫的顶质体中， 引起疟疾的寄生虫鉴于DXP/MEP途径的本质， 在这些生物体中，以及在哺乳动物中缺乏这种途径， 包括DXP/MEP途径的化合物代表用于产生 选择性抗菌剂和抗疟疾剂。为了更好地理解 这一途径的机制特征和随后形成的 关键的二磷酸中间体法呢基二磷酸（FPP），我们已经开始了 包括DXP/MEP途径的酶的结构解析和 分别由IPP异构酶和FPP合酶形成DMAPP和FPP， 使用蛋白质X射线晶体学。

DESCRIPTION: (provided by applicant) The long term objective of this research plan is to gain an understanding of the structural basis for isoprenoid biosynthesis in bacteria and parasites, which will serve as a foundation for the design of new classes of antibacterial and antimalarial agents. In particular, a key aim of this proposal is to understand the structural and mechanistic features governing the biosynthesis of the isoprenoid precursors isopentenyl disphosphate (IPP) and the isomeric compound, dimethylallyl diphosphate (DMAPP) catalyzed by enzymes comprising the mevalonate-independent pathway. In addition, the structural and functional analysis of a recently described and novel IPP isomerase that differs mechanistically and structurally from previously described IPP isomerases will be undertaken. This type 2 IPP isomerase, unlike the well-studied type 1 enzymes, depends on flavin mononucleotide and NADPH for activity. Notably, this type 2 class of IPP isomerase is found in several Gram-positive bacteria such as Staphylococcus aureus suggesting that it will serve as an effective target for new anti-staphylococcal drugs. Finally, the structure of the bacterial form of the enzyme farnesyl diphosphate synthase obtained from Escherichia coli will be determined. IPP and DMAPP are the fundamental building blocks of isoprenoids in all organisms and are essential metabolites for the construction of numerous higher order terpenoids. Recent independent studies demonstrated the existence of a novel, mevalonate-independent pathway for IPP synthesis known as the 1-deoxy-D-xylulose 5-phosphate / 2-C-methyl-D-erythritol 4-phosphate (DXP/MEP) pathway. This latter mevalonate-independent pathway utilizes pyruvate and glyceraldehyde 3-phosphate as starting materials for production of IPP. The DXPIMEP pathway occurs in a variety of eubacteria that includes several pathogenic species such as Mycobacterium tuberculosis, in algae, in the plastids of plant cells and in the apicoplast of Plasmodium falciparum the parasite that causes malaria. Given the essential nature of the DXP/MEP pathway in these organisms and the absence of this pathway in mammals, the enzymes comprising the DXP/MEP pathway represent targets for the generation of selective antibacterial and antimalarial agents. In order to better understand the mechanistic features of this pathway and the subsequent formation of a critical diphosphate intermediate farnesyl diphosphate (FPP), we have begun the structural elucidation of the enzymes comprising the DXP/MEP pathway and the formation of DMAPP and FPP from IPP isomerase and FPP synthase, respectively, using protein x-ray crystallography.