Cyanobacterial photosystem II at 2.9-Å resolution and the role of quinones, lipids, channels and chloride
Cyanobacterial photosystem II at 2.9-Å resolution and the role of quinones, lipids, channels and chloride
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DOI：
10.1038/nsmb.1559
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发表时间：
2009-03-01
影响因子：
16.8
通讯作者：
Saenger, Wolfram
中科院分区：
文献类型：
--
作者：
Guskov, Albert;Kern, Jan;Saenger, Wolfram
光系统II（PSII）是位于光合类囊体膜上的一个大的同源二聚体蛋白质-辅因子复合物，其充当光驱动的水：质体醌氧化还原酶。在2.9埃分辨率的PSII从细长热聚球藻的晶体结构允许所有20个蛋白质亚基的明确分配和所有35个叶绿素a分子和12个类胡萝卜素分子，25个积分脂质和1个氯离子每个单体的完整建模。第三plastoquinone QC和第二plastoquinone转移通道，这是以前没有观察到的存在下，表明plastoquinol-plastoquinone交换机制，我们计算了其他可能的水或分子氧和质子通道。从氙衍生物获得的推定的氧位置表明脂质在氧扩散到PSII的细胞质侧的作用。氯化物的位置表明在质子转移反应中的作用，因为它是通过一个假定的水分子在6.5埃的距离Mn 4Ca集群绑定，并接近两个可能的质子通道。(c)2009 Nature America，Inc. All rights reserved.
Photosystem II ( PSII) is a large homodimeric protein-cofactor complex located in the photosynthetic thylakoid membrane that acts as light-driven water: plastoquinone oxidoreductase. The crystal structure of PSII from Thermosynechococcus elongatus at 2.9-angstrom resolution allowed the unambiguous assignment of all 20 protein subunits and complete modeling of all 35 chlorophyll a molecules and 12 carotenoid molecules, 25 integral lipids and 1 chloride ion per monomer. The presence of a third plastoquinone QC and a second plastoquinone-transfer channel, which were not observed before, suggests mechanisms for plastoquinol-plastoquinone exchange, and we calculated other possible water or dioxygen and proton channels. Putative oxygen positions obtained from a Xenon derivative indicate a role for lipids in oxygen diffusion to the cytoplasmic side of PSII. The chloride position suggests a role in proton-transfer reactions because it is bound through a putative water molecule to the Mn4Ca cluster at a distance of 6.5 angstrom and is close to two possible proton channels. (c) 2009 Nature America, Inc. All rights reserved.