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首页> 外文期刊>Biochemistry >Binding Stoichiometry and Affinity of the Manganese-Stabilizing Protein Affects Redox Reactions on the Oxidizing Side of Photosystem II
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Binding Stoichiometry and Affinity of the Manganese-Stabilizing Protein Affects Redox Reactions on the Oxidizing Side of Photosystem II

机译：锰稳定蛋白的结合化学计量和亲和力影响光系统II氧化侧的氧化还原反应

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It has been reported previously that the two subunits of PsbO, the photosystem II (PSII) manganese stabilizing protein, have unique functions in relation to the Mn, Ca~(2+), and Cl- cofactors in eukaryotic PSII [Popelkova; et al. (2008) Biochemistry 47, 12593]. The experiments reported here utilize a set of N-terminal truncation mutants of PsbO, which exhibit altered subunit binding to PSII, to further characterize its role in establishing efficient O_2 evolution activity. The effects of PsbO binding stoichiometry, affinity, and specificity on Q_A- reoxidation kinetics after a single turnover flash, S-state transitions, and O_2 release time have been examined. The data presented here show that weak rebinding of a single PsbO subunit to PsbO-depleted PSII repairs many of the defects in PSII resulting from the removal of the protein, but many of these are not sustainable, as indicated by low steady-state activities of the reconstituted samples [Popelkova; et al. (2003) Biochemistry 42, 6193]. High affinity binding of PsbO to PSII is required to produce more stable and efficient cycling of the water oxidation reaction. Reconstitution of the second PsbO subunit is needed to further optimize redox reactions on the PSII oxidizing side. Native PsbOand recombinant wild-type PsbO from spinach facilitate PSII redox reactions in a very similar manner, and nonspecific binding of PsbO to PSII has no significance in these reactions.
机译：以前已经报道过，PsbO的两个亚基，光系统Ⅱ（PSII）锰稳定蛋白，与真核PSII中的Mn，Ca〜（2+）和Cl-辅因子具有独特的功能。等。 （2008）Biochemistry 47，12593]。本文报道的实验利用了一组PsbO的N端截短突变体，这些突变体表现出与PSII结合的改变的亚基，进一步表征了其在建立有效O_2进化活性中的作用。已经检查了PsbO结合化学计量，亲和力和特异性对单次翻转闪光，S状态转变和O_2释放时间后Q_A-再氧化动力学的影响。此处提供的数据表明，单个PsbO亚基与贫PsbO的PSII的弱重新结合可修复由于蛋白质去除引起的PSII中的许多缺陷，但许多缺陷是不可持续的，这表现为低稳态活性。复原后的样品[Popelkova;等。 （2003）Biochemistry 42，6193]。需要PsbO与PSII的高亲和力结合才能产生更稳定和有效的水氧化反应循环。需要重构第二个PsbO亚基，以进一步优化PSII氧化侧的氧化还原反应。来自菠菜的天然PsbO和重组野生型PsbO以非常相似的方式促进PSII氧化还原反应，并且PsbO与PSII的非特异性结合在这些反应中没有意义。

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