Mechanisms of Iron-Sulfur Dependent Reactions

铁硫依赖性反应的机制

• 批准号: 10406673
• 负责人: SQUIRE J. BOOKER
• 金额: $ 37.01万
• 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 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10406673
• 关键词: Anabolism; Antibiotic Resistance; Antibiotics; Antifungal Agents; Architecture; Biological; Biology; Carbapenems; Carbohydrates; Carbon; Cobalamin; DNA; Enzymes; Free Radicals; Health; Human; Hybrids; Iron; Lipids; Methylation; Methyltransferase; Natural Products; Nitrogen; Oxygen; Pathway interactions; Phosphorus; Prevalence; Process; Proteins; RNA; Reaction; Resistance; Resort; S-Adenosylhomocysteine; S-Adenosylmethionine; Source; Sulfur; System; Thiostrepton; Work; anti-cancer; base; carbanion; cofactor; enzyme structure; macromolecule; methyl group; small molecule; tRNA Methyltransferases

PROJECT SUMMARY/ABSTRACT The prevalence and significance of methylation reactions in biology is well established. Methyl groups are appended to a wide array of biological molecules, including numerous small-molecule metabolites and natural products, and various macromolecules, such as proteins, DNA, RNA, carbohydrates, and lipids. In the vast majority of methylation reactions, S-adenosylmethionine (SAM) is the source of the appended methyl group. In classical methyltransferase reactions, strong nucleophiles such as oxygen, nitrogen, and sulfur attack the sp3- hybridized methyl group of SAM in a polar SN2 reaction, affording S-adenosylhomocysteine as a co-product. Carbon atoms can also be methylated by this mechanism, but only if a suitably nucleophilic carbanion can be generated. Relatively recently, it has come to light that SAM can be used to methylate inert carbon or phosphinate phosphorous atoms via pathways involving radical intermediates. These noncanonical SAM- dependent methylations are found in numerous biosynthetic pathways for antibiotic, antifungal, anticancer, and herbicidal natural products, and are catalyzed exclusively by enzymes within the radical S- adenosylmethionine superfamily. Radical SAM methylases currently consist of three classes (Class A, Class B, and Class C) based on structural architecture, cofactor requirement, and mechanism of action. Class A enzymes use a Cys dyad to catalyze methylation of sp2-hybridized carbon centers. Class B enzymes use cobalamin cofactors to catalyze methylation of both sp2- and sp3-hybridized carbon centers. Class C enzymes use two simultaneously bound molecules of SAM to methylate sp2-hybridized carbon centers. In all cases, the appended methyl group derives from a second molecule of SAM. This work will continue our efforts to understand how these radical SAM methylases work, with a particular focus on efforts to determine structures of these enzymes with bound substrates, cofactors, and intermediates. Important systems include RNA methylases that are involved in antibiotic resistance, as well as methylases that are involved in the biosynthesis of important antibiotics, such as thiostrepton A, nosiheptide, and carbapenems, the antibiotics currently of last resort.

项目摘要/摘要 甲基化反应在生物学中的患病率和意义已得到很好的确定。甲基是 附加到广泛的生物分子上，包括许多小分子代谢物和天然 产物和各​​种大分子，例如蛋白质，DNA，RNA，碳水化合物和脂质。在广阔的地方 大多数甲基化反应，S-腺苷甲硫氨酸（SAM）是附加甲基的来源。在 经典的甲基转移酶反应，氧气，氮和硫等强的亲核试剂攻击SP3- 极性SN2反应中的SAM的杂交甲基，为S-腺基质型半胱氨酸作为共产力提供。 碳原子也可以通过这种机制甲基 生成。相对较最近，已经揭示了SAM可用于甲基化惰性碳或 磷酸磷酸原子通过涉及自由基中间体的途径。这些非规范的sam- 在许多生物合成途径中发现了依赖甲基，抗生素，抗真菌，抗癌， 和除草剂天然产物，并仅由根部S-内的酶催化 腺苷甲硫代超家族。激进的SAM甲基酶目前由三类（A类B类组成） c）基于结构结构，辅助因素和作用机理。 A类 酶使用Cys Dyad催化SP2杂交碳中心的甲基化。 B类酶的使用 钴胺素辅因子可催化SP2-和SP3杂交碳中心的甲基化。 C类酶 使用两个同时结合的SAM分子甲基化SP2杂交碳中心。在所有情况下， 附加的甲基源自SAM的第二个分子。这项工作将继续我们的努力 了解这些激进的SAM甲基酶如何工作，特别关注确定结构的努力 这些酶具有结合的底物，辅助因子和中间体。重要系统包括RNA 参与抗生素耐药性的甲基酶以及与生物合成有关的甲基化酶 重要的抗生素，例如硫代A，氧肽和碳青霉烯，目前是最后一次的抗生素 采取。