Collaboration between NDH and KEA3 Allows Maximally Efficient Photosynthesis after a Long Dark Adaptation
Collaboration between NDH and KEA3 Allows Maximally Efficient Photosynthesis after a Long Dark Adaptation
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DOI：
10.1104/pp.20.01069
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发表时间：
2020-12-01
期刊：
影响因子：
7.4
通讯作者：
Shikanai, Toshiharu
中科院分区：
文献类型：
--
作者：
Basso, Leonardo;Yamori, Wataru;Shikanai, Toshiharu
经过一夜的黑暗适应，其中一个循环电子传递途径与类囊体H+/K+逆向转运蛋白合作，有效地诱导光合作用。在被子植物中，NADH脱氢酶样（NDH）复合物介导PSI（CET）周围的循环电子传递。K+外排反向转运蛋白3（KEA 3）是一种假定的类囊体H+/K+反向转运蛋白，它以质子动力的pH分量为代价增加膜电位。在这项研究中，我们发现氯呼吸减少2 -1（crr 2 -1）突变消除了NDH依赖的CET，增强了拟南芥中kea 3 -1突变体的表型。NDH复合物在CET期间泵送质子，进一步提高pH，但其生理功能尚未完全阐明。观察到的效应仅在过夜暗适应后暴露于110 μ mol光子m（-2）s（-1）的光下时发生。我们提出了两种不同的NDH行动模式。在初始阶段，在光化光开始后1分钟内，NDH依赖性CET与KEA 3接合以增强电子传输效率。在随后的阶段，其中pH依赖的电子传递的下调被放松，NDH复合物与KEA 3接合以放松在初始阶段期间形成的大pH。我们观察到crr 2 -1突变在质子梯度调节5过表达系的遗传背景中的类似影响，其中pH的大小增加。当在300 μ mol光子m（-2）s（-1）诱导光合作用时，KEA 3的贡献在初始阶段可以忽略，并且在第二阶段pH依赖性下调没有放松。在crr 2 -1 kea 3 -1双突变体中，过夜暗适应后CO2固定的诱导延迟。
After overnight dark adaptation, one of the cyclic electron transport pathways collaborates with the thylakoid H+/K+ antiporter to efficiently induce photosynthesis. In angiosperms, the NADH dehydrogenase-like (NDH) complex mediates cyclic electron transport around PSI (CET). K+ Efflux Antiporter3 (KEA3) is a putative thylakoid H+/K+ antiporter and allows an increase in membrane potential at the expense of the pH component of the proton motive force. In this study, we discovered that the chlororespiratory reduction2-1 (crr2-1) mutation, which abolished NDH-dependent CET, enhanced the kea3-1 mutant phenotypes in Arabidopsis (Arabidopsis thaliana). The NDH complex pumps protons during CET, further enhancing pH, but its physiological function has not been fully clarified. The observed effect only took place upon exposure to light of 110 mu mol photons m(-2) s(-1) after overnight dark adaptation. We propose two distinct modes of NDH action. In the initial phase, within 1 min after the onset of actinic light, the NDH-dependent CET engages with KEA3 to enhance electron transport efficiency. In the subsequent phase, in which the pH-dependent down-regulation of the electron transport is relaxed, the NDH complex engages with KEA3 to relax the large pH formed during the initial phase. We observed a similar impact of the crr2-1 mutation in the genetic background of the PROTON GRADIENT REGULATION5 overexpression line, in which the size of pH was enhanced. When photosynthesis was induced at 300 mu mol photons m(-2) s(-1), the contribution of KEA3 was negligible in the initial phase and the pH-dependent down-regulation was not relaxed in the second phase. In the crr2-1 kea3-1 double mutant, the induction of CO2 fixation was delayed after overnight dark adaptation.