Radical SAM Enzyme HydE Generates Adenosylated Fe(I) Intermediates En Route to the [FeFe]-Hydrogenase Catalytic H-Cluster
Radical SAM Enzyme HydE Generates Adenosylated Fe(I) Intermediates En Route to the [FeFe]-Hydrogenase Catalytic H-Cluster
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DOI：
10.1021/jacs.0c03802
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发表时间：
2020-06-17
影响因子：
15
通讯作者：
Britt, R. David
中科院分区：
文献类型：
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作者：
Tao, Lizhi;Pattenaude, Scott A.;Britt, R. David
[FeFe]-氢化酶的H-簇由一个[4Fe-4S]（H）-亚簇通过半胱氨酰桥连接到一个独特的有机金属[2Fe]（H）-亚簇组成，该亚簇被指定为质子和分子氢之间的相互转化位点。该[2Fe]（H）-亚簇由一组Fe-S成熟酶HydG、HydE和HydF组装。在这里，我们表明HydG产物[Fe-II（Cys）（CO）（2）（CN）]合成子是自由基SAM酶HydE的底物，产生的5 '-脱氧腺苷基攻击半胱氨酸S形成C5'-S键，伴随着中心低自旋Fe（II）还原为Fe（I）氧化态。这导致半胱氨酸C3-S键断裂，产生单核[Fe-I（CO）（2）（CN）S]物质，其作为[2Fe]（H）-亚簇的双核Fe（I）Fe（I）中心的前体。这项工作揭示了HydE在H-簇的酶促组装中所起的作用，并扩大了自由基SAM酶化学的范围。
The H-cluster of [FeFe]-hydrogenase consists of a [4Fe-4S](H)-subcluster linked by a cysteinyl bridge to a unique organometallic [2Fe](H)-subcluster assigned as the site of inter-conversion between protons and molecular hydrogen. This [2Fe](H)-subcluster is assembled by a set of Fe-S maturase enzymes HydG, HydE and HydF. Here we show that the HydG product [Fe-II(Cys)(CO)(2)(CN)] synthon is the substrate of the radical SAM enzyme HydE, with the generated 5'-deoxyadenosyl radical attacking the cysteine S to form a C5'-S bond concomitant with reduction of the central low-spin Fe(II) to the Fe(I) oxidation state. This leads to the cleavage of the cysteine C3-S bond, producing a mononuclear [Fe-I(CO)(2)(CN)S] species that serves as the precursor to the dinuclear Fe(I)Fe(I) center of the [2Fe](H)-subcluster. This work unveils the role played by HydE in the enzymatic assembly of the H-cluster and expands the scope of radical SAM enzyme chemistry.