What can we still learn from the electrochromic band-shifts in Photosystem II?
What can we still learn from the electrochromic band-shifts in Photosystem II?
复制标题
我们还能从 Photosystem II 中的电致变色带移中学到什么？
DOI：
10.1016/j.bbabio.2020.148176
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
and M. Sugiura,
中科院分区：
文献类型：
--
作者：
A. Boussac;J. Selles;and M. Sugiura,
研究了长链热共胞球菌光系统II （PSII）的电致变色带移。首先，利用贫mn的PsbA1-PSII和PsbA3-PSII对phed1的qx吸收不同，在pH 8.6氧化TyrD时，发现了以~ 544 nm为中心的phed2的qx区有带移。相反，在PsbA3-PSII中，由于QA•-或TyrZ•的形成，在~ 546 nm处观察到带移，与E130 h键与PheD1的预期相同，与Q130 h键与PheD1的预期相同，为~ 544 nm。其次，在PsbA3-PSII中，在PsbA3/H198Q突变体中，在PsbA3/T179H突变体中，pd1的Soret带蓝移的PSII中，测量了ChlaSoret区域的电致变色带移位。TyrZ•QA•-形成后，pd1的Soret带发生红移，chld1的Soret带发生蓝移。相比之下，只有pd1经历了可检测的s态依赖电致变色。第三，除s1到S2外，所有s态跃迁中pd1的时间分辨s态电致变色都是双相的，并表明：1)从s1到s1的质子释放发生在电子转移中；2)从S2到S3的质子释放和电子转移动力学。长形，比通常认为的要快得多。根据文献中涉及s2到S3transition中间态的模型，讨论了S2TyrZ•的性质。
Electrochromic band-shifts have been investigated in Photosystem II (PSII) fromThermosynechoccocus elongatus. Firstly, by using Mn-depleted PsbA1-PSII and PsbA3-PSII in which the QXabsorption of PheD1differs, a band-shift in the QXregion of PheD2centered at ~ 544 nm has been identified upon the oxidation, at pH 8.6, of TyrD. In contrast, a band-shift due to the formation of either QA•-or TyrZ•is observed in PsbA3-PSII at ~ 546 nm, as expected with E130 H-bonded to PheD1and at ~ 544 nm as expected with Q130 H-bonded to PheD1. Secondly, electrochromic band-shifts in the ChlaSoret region have been measured in O2-evolving PSII in PsbA3-PSII, in the PsbA3/H198Q mutant in which the Soret band of PD1is blue shifted and in the PsbA3/T179H mutant. Upon TyrZ•QA•-formation the Soret band of PD1is red shifted and the Soret band of ChlD1is blue shifted. In contrast, only PD1undergoes a detectable S-state dependent electrochromism. Thirdly, the time resolved S-state dependent electrochromism attributed to PD1is biphasic for all the S-state transitions except for S1to S2, and shows that:i) the proton release in S0to S1occursafterthe electron transfer andii) the proton release and the electron transfer kinetics in S2to S3, inT. elongatus, are significantly faster than often considered. The nature of S2TyrZ•is discussed in view of the models in the literature involving intermediate states in the S2to S3transition.