Photoassembly of the manganese cluster in mutants perturbed in the high affinity Mn-binding site of the H2O-oxidation complex of photosystem II.
Photoassembly of the manganese cluster in mutants perturbed in the high affinity Mn-binding site of the H2O-oxidation complex of photosystem II.
复制标题
突变体中锰簇的光组装在光系统 II 的 H2O 氧化复合物的高亲和力 Mn 结合位点受到干扰。
DOI：
10.1021/bi700761v
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发表时间：
2007
期刊：
影响因子：
2.9
通讯作者：
Burnap,RobertL
中科院分区：
文献类型：
--
作者：
Hwang,HongJin;McLain,Aaron;Debus,RichardJ;Burnap,RobertL
光驱动的 Mn2+ 离子氧化组装成光系统 II (PSII) 反应中心的 H2O-氧化络合物 (WOC) 称为光活化，并最终形成 WOC 的析氧 (Mn4−Ca) 中心。 Mn2+ 与脱辅基蛋白的初始结合和光氧化很大程度上取决于高亲和力 Mn 位点的 D1 蛋白 (D1−D170) 的天冬氨酸 170 [Nixon 和 Diner (1992)Biochemistry31, 942−948]。研究了集胞藻的三种 O2 进化突变株 D1−D170E、D1−D170H 和 D1−D170V 在连续光和闪烁光下的光活化动力学。使用单周转闪光的光激活显示，D1−D170H 和 D1−D170V，但不是 D1−D170E，易于形成大量（∼40−50%）的失活中心，归因于基于失活的可逆性和与先前体外结果的相似性的异常非功能性 Mn 的光连接 [Chen, C.、Kazimir, J. 和 Cheniae, G. M. (1995)生物化学 34, 13511−13526]。另一方面，与野生型相比，D1−D170E 降低了光活化的量子效率，降幅最大（降低 80%），而 D1−D170H 和 D1−D170V 不会产生可测量的量子效率下降。 D1−D170E 中光活化的低量子效率是由于光活化中间体的不稳定造成的。数值分析表明，D1−D170E 中的 PSII 中心在光活化动力学方面是异质的，并且大多数中心的特征是中间体的衰减速度比野生型对照快约 10 倍。此外，与 D1-D170H 和 D1-D170V 相比，D1-D170E 中 S3−S0 转变期间 O2 释放的动力学显着延迟，与野生型相比，D1-D170H 和 D1-D170V 没有表现出明显的减慢。
The light-driven, oxidative assembly of Mn2+ions into the H2O-oxidation complex (WOC) of the photosystem II (PSII) reaction center is termed photoactivation and culminates in the formation of the oxygen-evolving (Mn4−Ca) center of the WOC. Initial binding and photooxidation of Mn2+to the apoprotein is critically dependent upon aspartate 170 of the D1 protein (D1−D170) of the high affinity Mn site [Nixon and Diner (1992)Biochemistry31, 942−948]. Three O2-evolving mutant strains ofSynechocystis, D1−D170E, D1−D170H, and D1−D170V, were studied in terms of the kinetics of photoactivation under both continuous and flashing light. Photoactivation using single turnover flashes revealed D1−D170H and D1−D170V, but not D1−D170E, were prone to form substantial amounts (∼40−50%) of inactive centers ascribed to photoligation of aberrant nonfunctional Mn based upon the reversibility of the inactivation and similarity to previousin vitroresults [Chen, C., Kazimir, J., and Cheniae, G. M. (1995)Biochemistry 34, 13511−13526]. On the other hand, D1−D170E lowers the quantum efficiency of photoactivation compared to the wild-type by the largest amount (80% decrease) versus D1−D170H and D1−D170V, which do not produce measurable decreases in quantum efficiency. The low quantum efficiency of photoactivation in D1−D170E is due to the destabilization of photoactivation intermediates. Numerical analysis indicates that the PSII centers in D1−D170E are heterogeneous with respect to photoactivation kinetics and that the majority of centers are characterized by intermediates that decay ∼10-fold more rapidly than the wild-type control. Additionally, the kinetics of O2release during the S3−S0transition was markedly retarded in D1-D170E, in contrast to D1-D170H and D1-D170V, which did not exhibit a discernible slow-down compared to the wild-type.