BIOSYNTHESIS OF CYCLOPENTANOIDS

环戊烷类化合物的生物合成

• 批准号: 2174738
• 负责人: RONALD J PARRY
• 金额: $ 17.16万
• 依托单位: RICE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-01 至 1996-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2174738
• 关键词: Pseudomonas; Streptomyces; antibiotics; antifungal antibiotics; biosynthesis; cell free system; chemical structure; cyclopentane; enzyme substrate; microorganism metabolism; nucleoside analog; plant poisons

It is proposed to investigate the biosynthesis of two cyclopentanoid natural products. The first is the nucleoside antibiotic aristeromycin, a cyclopentyl analog of adenosine produced by Streptomyces citricolor and accompanied by the closely related antitumor and antiviral agent neplanocin A. Previous investigations of aristeromycin biosynthesis revealed that the adenine ring is biosynthesized along familiar lines, while the cyclopentane ring of the antibiotic is generated by C-C bond formation between C-2 and C-6 of glucose. The mechanism of cyclopentane ring formation was probed using specifically tritiated forms of glucose. Isotope dilution experiments provided evidence for the presence of the cyclopentyl analogs of ribose-5-phosphate and 5-phosphoribosyl-1-amine in extracts of S. citricolor. Future studies will investigate the formation of the cyclopentyl analogs of ribose-5-phosphate, PRPP, and 5- phosphoribosyl-1-amine in cell-free extracts of S. citricolor. The formation of the cyclopentyl analog of AMP (aristeromycin-5'- monophosphate) in cell-free extracts will also be investigated, since previous studies indicate that aristeromycin can be biosynthesized via the purine salvage pathway. Investigations will also be carried out with purified forms of three enzymes involved in the biosynthesis of adenosine in bacteria. The goal of these studies will be to determine whether these enzymes can utilize the cyclopentyl analogs of their normal substrates. The results should provide insight into the nature of some of the enzymes involved in aristeromycin biosynthesis and may allow the enzymatic synthesis of one or more of the intermediates in the aristeromycin pathway. If the purine biosynthetic enzymes will utilize the cyclopentyl analogs, then these enzymes could also be used in coupled assays for the formation of cyclopentyl compounds in S. citricolor extracts. The second cyclopentanoid to be investigated is the phytotoxin coronatine, which is produced by Pseudomonas syringae. Previous investigations have revealed that the hydrindane portion of the molecule, coronafacic acid, is a novel polykeytide derived from five acetate units and one pyruvate unit. The cyclopropyl amino acid moiety of the toxin, coronamic acid, has been found to be biosynthesized from L-alloisoleucine by an unusual process that appears to be related to the oxidative cyclizations associated with the biosynthesis of the beta- lactam antibiotics. Future studies of coronatine biosynthesis will include an attempt to clarify the mode of assembly of the hydrindane ring and will examine the mechanism of the biosynthesis of coronamic acid in further detail. The investigations should be greatly facilitated by a collaboration with Dr. Carol Bender of Oklahoma State University, who is cloning the genes for the coronatine biosynthetic pathway. Finally, the investigations of coronamic acid biosynthesis will be extended to an investigation of the mechanism of biosynthesis of 3- ethylidene-L-azetidine-2-carboxylic acid (polyoximic acid) from L- isoleucine. Polyoximic acid is a component of the polyoxins, a group of antifungal antibiotics produced by S. cacaoi var. asoensis.

提议研究两个环戊酸的生物合成 天然产品。首先是核苷抗生素瘤霉素， 链霉菌产生的腺苷的环戊烯基类似物 并伴随着密切相关的抗肿瘤和抗病毒剂 NeplanocinA。先前对瘤霉素生物合成的研究 揭示腺嘌呤环是沿熟悉的线生物合成的 而抗生素的环烷环由C-C键产生 葡萄糖的C-2和C-6之间的形成。环戊烷的机制 使用特异性的葡萄糖形式探测环形成。 同位素稀释实验为存在的证据提供了证据 5-磷酸核糖和5-磷酸蛋白酶基-1-胺的环戊烯基类似物 在柠檬色的提取物中。未来的研究将调查 5-磷酸核糖，PRPP和5-的环戊烯基类似物的形成 柠檬色链球菌中无细胞提取物中的磷酸贝糖基-1-胺。这 AMP的环戊烯基类似物的形成（瘤霉素5'-- 也将研究无细胞提取物中的单磷酸盐），因为 先前的研究表明，瘤霉素可以通过 嘌呤打捞路径。调查也将与 参与生物合成的三种酶的纯化形式 细菌中的腺苷。这些研究的目的是确定 这些酶是否可以利用其环戊烯类似物的类似物 正常底物。结果应提供对的性质 一些参与瘤霉素生物合成的酶，可能允许 一个或多个中间体的酶促合成 瘤霉素途径。如果将使用嘌呤生物合成酶 环戊烯类似物，然后这些酶也可以在 耦合的测定法用于形成S.中环戊烯化合物的测定法 柠檬色提取物。要研究的第二个环戊糖苷是 植物毒素冠脉，由丁香假单胞菌产生。 先前的调查显示， 分子，冠状酸，是一种衍生自五个的新型多钥匙丁物 乙酸单元和一个丙酮酸单元。环丙基氨基酸部分 毒素，冠状酸的冠状酸是生物合成的 L-异亮氨酸氨基氨酸盐通过似乎与 与β-的生物合成相关的氧化循环 LACTAM抗生素。冠状动脉生物合成的未来研究将 包括试图阐明水合烷的组装方式 环，将检查冠状动脉生物合成的机理 酸进一步详细。调查应大大促进 与俄克拉荷马州立大学的Carol Bender博士合作， 谁是克隆冠状生物合成途径的基因。 最后，冠状酸生物合成的研究将是 扩展到研究3-的生物合成机理 乙烯-l-唑替丁-2-羧酸（多氧化酸）的L- 异亮氨酸。多氧合酸是多氧的组成部分，一组 S. cacaoi Var产生的抗真菌抗生素。 Asoensis。