Higher order structure contributes to specific differences in redox potential and electron transfer efficiency of root and leaf ferredoxins
Higher order structure contributes to specific differences in redox potential and electron transfer efficiency of root and leaf ferredoxins
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DOI：
10.1021/bi061779d
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发表时间：
2006-12-05
期刊：
影响因子：
2.9
通讯作者：
Hase, Toshiharu
中科院分区：
文献类型：
--
作者：
Gou, Ping;Hanke, Guy T.;Hase, Toshiharu
植物型铁氧还蛋白（Fd）是一种含[2Fe-2S]簇的电子传递蛋白，具有高度负的氧化还原电位。高等植物的根和叶中含有不同的Fd同工蛋白类型，反映了这两种组织之间氧化还原级联反应的差异。我们结合了重组嵌合体中的叶和根FDS的亚结构域，以研究结构效应和残基组之间的关系对氧化还原电位，电子转移和蛋白质-蛋白质相互作用。所有嵌合体具有与野生型叶和根Fds中等的氧化还原电位。令人惊讶的是，最大的差异来自N-末端的交换，该区域距离氧化还原中心最远。同源建模和能量最小化计算表明，N-末端嵌合体可能间接影响氧化还原电位的结构扰动的活性位点。电子传递和蛋白质相互作用的测量表明，根Fd的C-和N-末端之间的协同相互作用赋予一个特定的高亲和力接受电子的根型电子级联，并有歧视光合电子捐赠根Fd的基础上的C-末端的分子。两者合计，实验和计算研究支持一个模型，在该模型中，高阶结构有助于异蛋白质特异性相互作用和电子转移性质。
Plant type ferredoxin (Fd) is a small [2Fe-2S] cluster containing electron-transfer protein with a highly negative redox potential. Higher plants contain different iso-protein types of Fd in roots and leaves, reflecting the difference in redox cascades between these two tissues. We have combined subdomains of leaf and root Fds in recombinant chimeras, to examine structural effects and the relationship between groups of residues on redox potential, electron transfer, and protein-protein interactions. All chimeras had redox potentials that were intermediate to the wild type leaf and root Fds. Surprisingly, the largest differences resulted from exchange of the N-terminus, the region farthest from the redox center. Homology modeling and energy minimization calculations suggest that the N-terminal chimeras may indirectly influence redox potentials by structurally perturbing the active site. Measurements of electron transport and protein interaction indicate that synergistic interaction between the C- and N-terminal of root Fd bestows a specific high affinity for accepting electrons in the root type electron cascade, and that there is discrimination against photosynthetic electron donation to root Fd based on the C-terminus of the molecule. Taken together, the experimental and computational studies support a model in which higher order structure contributes to iso-protein specific interaction and electron-transfer properties.