Electron transfer complex formation between oxygenase and ferredoxin components in Rieske nonheme iron oxygenase system
Electron transfer complex formation between oxygenase and ferredoxin components in Rieske nonheme iron oxygenase system
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DOI：
10.1016/j.str.2006.10.004
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发表时间：
2006-12-01
期刊：
影响因子：
5.7
通讯作者：
Nojiri, Hideaki
中科院分区：
文献类型：
--
作者：
Ashikawa, Yuji;Fujimoto, Zui;Nojiri, Hideaki
咔唑 1,9a-双加氧酶 (CARDO) 是 Rieske 非血红素铁加氧酶系统 (ROS) 的成员，由末端加氧酶 (CARDO-0) 和电子转移组件（铁氧还蛋白 [CARDO-F] 和铁氧还蛋白还原酶 [CARDO-R]）组成。我们分别以 1.9、1.8 和 2.0 埃的分辨率确定了 CARDO-0 及其电子供体 CARDO-F 的非还原、还原和底物结合二元复合物的晶体结构。这些结构为ROS中铁氧还蛋白和加氧酶的两个Rieske [2Fe-2S]簇之间的组分间电子转移提供了第一个基于结构的解释。三个 CARDO-F 分子与一个 CARDO-O 三聚体分子的亚基边界结合，静电和疏水相互作用与构象变化产生的特异性结合适当地对齐两个 Rieske 簇以进行电子转移。此外，结合咔唑时的构象变化导致底物结合袋上的盖子闭合，从而似乎将咔唑捕获在底物结合位点。
Carbazole 1,9a-dioxygenase (CARDO), a member of the Rieske nonheme iron oxygenase system (ROS), consists of a terminal oxygenase (CARDO-0) and electron transfer components (ferredoxin [CARDO-F] and ferredoxin reductase [CARDO-R]). We determined the crystal structures of the nonreduced, reduced, and substrate-bound binary complexes of CARDO-0 with its electron donor, CARDO-F, at 1.9, 1.8, and 2.0 angstrom resolutions, respectively. These structures provide the first structure-based interpretation of intercomponent electron transfer between two Rieske [2Fe-2S] clusters of ferredoxin and oxygenase in ROS. Three molecules of CARDO-F bind to the subunit boundary of one CARDO-O trimeric molecule, and specific binding created by electrostatic and hydrophobic interactions with conformational changes suitably aligns the two Rieske clusters for electron transfer. Additionally, conformational changes upon binding carbazole resulted in the closure of a lid over the substrate-binding pocket, thereby seemingly trapping carbazole at the substrate-binding site.