Stabilization of the Mn cluster by Y_D tyrosine in oxygen evolving complex of photosystem II

Y_D 酪氨酸对光系统 II 放氧复合物中 Mn 簇的稳定性

• 批准号: 13640659
• 负责人: ONO Takaaki
• 金额: $ 1.28万
• 依托单位: The Institute of Physical and Chemical Research
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640659/
• 关键词: photosynthesis; photosystem II; oxygen evolution; tyrosine D; manganese cluster; Chlamydomonas; D2 protein; green alga; 光化学系; 酸素電極; クラミドモナス; Y_Dチロシン; FTIR; ESR; 部位特異変異; TDチロシン

Function of a redox active Y_D tyrosine residue in photosystem II has been studied by the use of the unicellular green alga Chlamydomonas reinhardtii, in which the tyrosine for Y_D (the 160th tyrosine of the D2 protein) was replaced by phenylalanine by site-directed mutagenesis using His-tagged psbD plasmid. The processes of S state transition in photosynthetic oxygen evolution was monitored by analyzing the flash-induced oxygen evolution using a home-made high sensitive Joliot-type O_2 electrode, which enable us to measure the flash O_2 pattern of cultured algal cells directly without further condensation. In the mutant cells, no fast component was detected in the dark decay from O_2 to S_1 but slow decaying component was normal as compared with the wild-type cells, indicating the direct involvement of Y_D tyrosine in the fast decaying process. The flash O_2 pattern did not change even after prolonged dark incubation, indicating that Y_D does not contribute the redox equilibration between S_1 and S_0. Therefore, higher stability of S_1 than S_0 is predominantly ascribed to their thermodynamic natures.Furthermore, the absence of Y_D tyrosine did not affect the O_2 capability after long dark incubation. The results show that Y_D is not involved in the stability of The Mn cluster in the dark. In fact, PS II cores with high O_2 activity were prepared from the mutants by means of Ni-affinity column chromatography. This preparation is useful for the physicochemical studies, including ESR and FTIR, on photosystem II.

本文以单细胞绿色衣藻Chlamydiumreinhardtii为材料，研究了光系统Ⅱ中具有氧化还原活性的Y_D酪氨酸残基的功能。利用自行研制的高灵敏度Joliot型O_2电极，通过分析闪光诱导的光合放氧过程，监测了光合放氧过程中S态的转变过程，使我们能够直接测量培养藻细胞的闪光O_2模式，而不需要进一步的冷凝。在突变体细胞中，从O_2到S_1的暗衰变中未检测到快衰变成分，而慢衰变成分与野生型细胞相比正常，表明Y_D酪氨酸直接参与了快衰变过程。闪光O_2模式即使在长时间的黑暗培养后也没有变化，表明Y_D对S_1和S_0之间的氧化还原平衡没有贡献。因此，S_1比S_0具有更高的稳定性主要归因于它们的热力学性质。结果表明，Y_D不影响Mn团簇在黑暗中的稳定性。事实上，通过镍亲和柱层析，从突变体中制备了具有高O_2活性的PS II核心。该制剂可用于光系统II的物理化学研究，包括ESR和FTIR。

项目成果

K.Hasegawa: "Ab Initio DFT calculations and vibrational analysis of zinc-bound 4-methylimidazole as the model of a histidine ligand in metalloenzymes"J.Chem.Phys.A. 106. 3377-3390 (2002)

K.Hasekawa：“作为金属酶中组氨酸配体模型的锌结合 4-甲基咪唑的从头开始 DFT 计算和振动分析”J.Chem.Phys.A。

H.Teramoto, T.Ono, J.Minagawa: "Identification of Lheb gene family encoding the light-harvesting chlorophyll-a/b proteins of photosystem II in Chlamydomonas reinharditii"Plant Cell Physiology. 42. 849-856 (2001)

H.Teramoto、T.Ono、J.Minakawa：“编码莱茵衣藻光系统 II 的捕光叶绿素-a/b 蛋白的 Lheb 基因家族的鉴定”植物细胞生理学。

Kimura, Y., Hasegawa, K. and Ono, T.: "Characteristics changes of the S_2/S_1 difference FTIR spectrum induced by Ca^<2+>-depletion and metal cation substitution in photosynthetic oxygen evolving complex."Biochemistry. 41. 5844-5653 (2002)

Kimura, Y.、Hasekawa, K. 和 Ono, T.：“光合产氧复合物中 Ca^2-耗尽和金属阳离子取代引起的 S_2/S_1 差异 FTIR 光谱的特征变化。”生物化学。

Y.Kimura: "Characteristic changes of the S_2/S_1 difference FTIR spectrum induced by Ca^<2+>-depletion and metal cation substitution in photosynthetic oxugen evolving complex"Biochemistry. 41. 5844-5653 (2002)

Y.Kimura：“光合产氧复合物中 Ca^2-耗尽和金属阳离子取代引起的 S_2/S_1 差异 FTIR 光谱的特征变化”生物化学。

Y.Kimura: "Chelator-induced disappearance of carboxylate stretching vibrational modes in S_1/S_2 FTIR spectrum in oxygen-evolving complex of photosystem II"Biochemistry. 40. 14064-14068 (2001)

Y.Kimura：“光系统 II 的放氧复合物中 S_1/S_2 FTIR 光谱中羧酸伸缩振动模式的螯合剂诱导消失”生物化学。