Radical SAM catalysis via an organometallic intermediate with an Fe-[5'-C]-deoxyadenosyl bond.
Radical SAM catalysis via an organometallic intermediate with an Fe-[5'-C]-deoxyadenosyl bond.
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DOI：
10.1126/science.aaf5327
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发表时间：
2016-05-13
期刊：
影响因子：
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通讯作者：
Broderick JB
中科院分区：
文献类型：
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作者：
Horitani M;Shisler K;Broderick WE;Hutcheson RU;Duschene KS;Marts AR;Hoffman BM;Broderick JB
自由基SAM酶利用[4Fe-4S]簇裂解S-腺苷甲硫氨酸(SAM)，启动各种自由基反应。它们被认为涉及尚未被检测到的5‘-脱氧腺苷自由基中间体。在这里，我们快速冷冻-淬火捕捉在自由基SAM酶丙酮酸甲酸裂解酶激活酶催化的反应中具有催化活性的中间体。通过电子顺磁共振和~(13)C，~(57)Fe电子-核双共振谱对该中间体进行了表征，结果表明，该中间体含有一个有机金属中心，其中SAM衍生的脱氧腺苷部分的5‘-碳与[4Fe-4S]团簇中唯一的铁形成了一个键。该中间体的发现将酶生物有机金属中心的名单扩展到自由基SAM酶，这是已知的最大的酶超家族，并揭示了与B12自由基酶有趣的相似之处。
Radical SAM enzymes use a [4Fe-4S] cluster to cleave S-adenosylmethionine (SAM) to initiate diverse radical reactions. These are thought to involve the 5′-deoxyadenosyl radical intermediate, which has not yet been detected. Here we rapid freeze-quench trap a catalytically competent intermediate in the reaction catalyzed by the radical SAM enzyme pyruvate formate-lyase activating enzyme. Characterization of the intermediate by electron paramagnetic resonance and 13C, 57Fe electron-nuclear double resonance spectroscopies reveals that it contains an organometallic center in which 5′-carbon of a SAM-derived deoxyadenosyl moiety forms a bond to the unique iron of the [4Fe-4S] cluster. Discovery of this intermediate extends the list of enzymatic bio-organometallic centers to the radical SAM enzymes, the largest enzyme superfamily known, and reveals intriguing parallels to B12 radical enzymes.