Desulfovibrio desulfuricans iron hydrogenase:: the structure shows unusual coordination to an active site Fe binuclear center
Desulfovibrio desulfuricans iron hydrogenase:: the structure shows unusual coordination to an active site Fe binuclear center
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DOI：
10.1016/s0969-2126(99)80005-7
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发表时间：
1999-01-15
期刊：
影响因子：
5.7
通讯作者：
Fontecilla-Camps, JC
中科院分区：
文献类型：
--
作者：
Nicolet, Y;Piras, C;Fontecilla-Camps, JC
背景资料：许多微生物有能力氧化分子氢产生还原力或产生氢，以消除低电位电子，这些反应是由两个不相关的酶催化：Ni-Fe氢化酶和Fe-唯一的氢化酶，结果：我们在这里报告的异二聚体Fe-唯一的氢化酶脱硫弧菌的结构-这类酶的第一个。除了铁氧还蛋白样结构域之外，该结构代表了一种新的蛋白质折叠，该酶的所谓H簇由典型的[4Fe-4S]立方烷桥连到双核活性位点Fe中心（含有推定的CO和CN配体）和一个桥连1，3-丙二硫醇分子组成，亚基的构象可以解释为单体细胞质酶转化为二聚体周质酶的进化变化。结论：Ni-Fe氢化酶和纯Fe氢化酶的活性中心具有以下共同特征：双原子配体与Fe离子配位，其中一个金属离子上的空配位点代表可能的底物结合点，一个硫醇桥双核中心，一个金属离子上的空配位点代表可能的底物结合点。以及合理的质子和电子转移途径和底物通道。与Fe离子的双原子配位使它们具有低自旋并有利于低氧化还原态，这可能是催化所需的。复杂的电子顺磁共振信号典型的铁只有氢化酶产生的[4Fe-4S]簇和活性位点双核中心之间的磁相互作用，该中心的蛋白质配体的缺乏表明，它是从无机世界进口作为一个已经功能单位。
Background: Many microorganisms have the ability to either oxidize molecular hydrogen to generate reducing power or to produce hydrogen in order to remove low-potential electrons, These reactions are catalyzed by two unrelated enzymes: the Ni-Fe hydrogenases and the Fe-only hydrogenases,Results: We report here the structure of the heterodimeric Fe-only hydrogenase from Desulfovibrio desulfuricans - the first for this class of enzymes. With the exception of a ferredoxin-like domain, the structure represents a novel protein fold, The so-called H cluster of the enzyme is composed of a typical [4Fe-4S] cubane bridged to a binuclear active site Fe center containing putative CO and CN ligands and one bridging 1,3-propanedithiol molecule, The conformation of the subunits can be explained by the evolutionary changes that have transformed monomeric cytoplasmic enzymes into dimeric periplasmic enzymes. Plausible electron- and protontransfer pathways and a putative channel for the access of hydrogen to the active site have been identified.Conclusions: The unrelated active sites of Ni-Fe and Fe-only hydrogenases have several common features: coordination of diatomic ligands to an Fe ion; a vacant coordination site on one of the metal ions representing a possible substrate-binding site; a thiolate-bridged binuclear center; and plausible proton- and electron-transfer pathways and substrate channels. The diatomic coordination to Fe ions makes them low spin and favors low redox states, which may be required for catalysis. Complex electron paramagnetic resonance signals typical of Fe-only hydrogenases arise from magnetic interactions between the [4Fe-4S] cluster and the active site binuclear center, The paucity of protein ligands to this center suggests that it was imported from the inorganic world as an already functional unit.