A conformational mimic of the MgATP-bound "on state" of the nitrogenase iron protein.
A conformational mimic of the MgATP-bound "on state" of the nitrogenase iron protein.
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固氮酶铁蛋白的 MgATP 结合“开启状态”的构象模拟。
DOI：
10.1021/bi0358465
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Peters,JohnW
中科院分区：
文献类型：
--
作者：
Sen,Sanchayita;Igarashi,Robert;Smith,Archer;Johnson,MichaelK;Seefeldt,LanceC;Peters,JohnW
固氮酶 Fe 蛋白单位点缺失变体的晶体结构揭示了 Fe 蛋白的一种明显新的构象，并表明在与 MgATP 结合后，Fe 蛋白经历了显着的构象变化，这在很大程度上表现为同二聚体 Fe 蛋白亚基相对于彼此的刚体重新定向。观察到的构象状态使得结构和化学互补相互作用的模型合理化，该模型在与 MoFe 蛋白质组分形成初始复合物时发生，这与之前针对稳定固氮酶复合物表征的蛋白质-蛋白质相互作用不同。晶体学结果与互补的紫外可见吸收、EPR 和共振拉曼光谱数据相结合，表明在 MgATP 存在下，Fe 蛋白缺失变体和天然 Fe 蛋白的 [4Fe-4S] 簇可以在还原态的常规立方烷型 [4Fe-4S] 簇和涉及两个原子的裂解形式之间可逆循环。 氧化态的[2Fe-2S]碎片。共振拉曼研究表明，这种新颖的簇转化是由甘油诱导的，并且晶体学数据表明甘油作为桥接双齿配体与氧化态的两个 [2Fe-2S] 簇片段结合。
The crystal structure of a nitrogenase Fe protein single site deletion variant reveals a distinctly new conformation of the Fe protein and indicates that, upon binding of MgATP, the Fe protein undergoes a dramatic conformational change that is largely manifested in the rigid-body reorientation of the homodimeric Fe protein subunits with respect to one another. The observed conformational state allows the rationalization of a model of structurally and chemically complementary interactions that occur upon initial complex formation with the MoFe protein component that are distinct from the protein−protein interactions that have been characterized previously for stabilized nitrogenase complexes. The crystallographic results, in combination with complementary UV−visible absorption, EPR, and resonance Raman spectroscopic data, indicate that the [4Fe-4S] cluster of both the Fe protein deletion variant and the native Fe protein in the presence of MgATP can reversibly cycle between a regular cubane-type [4Fe-4S] cluster in the reduced state and a cleaved form involving two [2Fe-2S] fragments in the oxidized state. Resonance Raman studies indicate that this novel cluster conversion is induced by glycerol, and the crystallographic data suggest that glycerol is bound as a bridging bidentate ligand to both [2Fe-2S] cluster fragments in the oxidized state.