Radical Mechanisms of Iron-Sulfur Proteins

铁硫蛋白的自由基机制

• 批准号: 9277146
• 负责人: SQUIRE J. BOOKER
• 金额: $ 29.88万
• 依托单位: PENNSYLVANIA STATE UNIVERSITY, THE
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9277146
• 关键词: Aerobic Bacteria; Amaze; Anabolism; Anaerobic Bacteria; Antibiotic Resistance; Antibiotics; Carbon; Cleaved cell; DNA Repair; DNA biosynthesis; Disease; Dissociation; Enzymes; Free Radicals; Genome; Health; Human; Hydrogen; Hydrogen Bonding; Individual; Iron; Iron-Sulfur Proteins; Laboratories; Methods; Methylation; Methyltransferase; Modification; Pathway interactions; Phosphorus; Play; Process; Proteins; Reaction; Resistance; Ribosomes; Role; S-Adenosylmethionine; Source; Sulfur; Thioctic Acid; Transfer RNA; Transition Elements; Viral; Work; cobamamide; cofactor; member; novel

PROJECT SUMMARY Elaborations of unactivated carbon centers are among the most demanding reactions that enzymes catalyze. These reactions generally involve radical intermediates, often produced by strategic abstraction of substrate hydrogen atoms (H·). A prevalent strategy to cleave C–H bonds possessing homolytic bond-dissociation energies (BDEs) in excess of 95 kcal/mol involves intermediates derived from the reaction of O2 with transition metal cofactors. A distinct strategy, predominant in the anaerobic world and still important in aerobes, employs a 5'-deoxyadenosyl 5'-radical as the H· abstractor. This radical is generated via the homolysis of adenosylcobalamin (AdoCbl) or the reductive cleavage of S-adenosylmethionine (SAM). Those enzymes employing SAM to catalyze radical-dependent reactions belong to the so-called radical SAM (RS) superfamily, which contains almost 114,000 individual sequences that encompass at least 65 distinct reactions. Moreover, the number of enzymes and reactions catalyzed by members of the superfamily are increasing at an amazing pace as sequences of new genomes become available. The work described herein builds on and advances work from our laboratory on the characterization of some of the most novel reactions within the superfamily, including those involved in tRNA and ribosome modification, lipoic acid biosynthesis, the biosynthesis of several antibiotics, and antibiotic resistance. Specific objectives will be to i) elucidate how methylation of unactivated carbon and phosphorus atoms takes place, and provide rationale for the strategy employed for each type of methyl acceptor; ii) formulate methods to determine substrates for the many unannotated radical SAM methylases; iii) elucidate how iron-sulfur clusters are used as sources of sulfur atoms during sulfur insertion reactions and to determine how they are resynthesized after each turnover; iv) elucidate the pathway for the biosynthesis of the thiopeptide antibiotic, nosiheptide; and v) begin to characterize several radical SAM enzymes from humans that play important roles in health and disease.

项目摘要 未活化的碳中心的阐述是催化酶的最苛刻的反应之一。 这些反应通常涉及自由基中间体，通常由底物的战略抽象产生 氢原子（H·）。清除具有同型债券解决的C – H债券的普遍策略 超过95 kcal/mol的能量（BDE）涉及源自O2反应与过渡的中间体 金属辅因子。一个独特的策略，在厌氧界占主导地位，在健美动物中仍然很重要， 使用5'-脱氧丁糖基5'-Radical作为H·抽象器。通过 腺苷胆素（ADOCBL）或S-腺苷甲氨酸（SAM）的裂解降低。那些酶 采用SAM催化自由基依赖性反应属于所谓的自由基SAM（RS）超家族， 其中包含近114,000个单独的序列，其中包含至少65个不同的反应。而且， 超家族成员催化的酶和反应的数量在惊人的情况下增加 随着新基因组序列的速度可用。本文所描述的工作是建立和进步的工作 从我们的实验室来表征超家族中一些最新反应的表征 包括参与tRNA和核糖体修饰的那些，lipoic酸生物合成，生物合成的生物合成 几种抗生素和抗生素抗性。特定目标将是i）阐明如何 未活化的碳和磷原子发生，并为用于 每种类型的甲基受体； ii）制定方法来确定许多未注释的自由基的底物 SAM甲基酶； iii）阐明如何将铁硫簇用作硫期间硫原子的来源 插入反应并确定每次失误后如何重新合成它们； iv）阐明途径 为了硫代肽抗生素的生物合成； v）开始表征几个激进的SAM 人类的酶在健康和疾病中起重要作用。