Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA.
Photosynth Res. 2018 Apr;136(1):107-124. doi: 10.1007/s11120-017-0447-y. Epub 2017 Oct 3.
Photosystem II is known to be a highly dynamic multi-protein complex that participates in a variety of regulatory and repair processes. In contrast, photosystem I (PSI) has, until quite recently, been thought of as relatively static. We report the discovery of plant PSI-LHCII megacomplexes containing multiple LHCII trimers per PSI reaction center. These PSI-LHCII megacomplexes respond rapidly to changes in light intensity, as visualized by native gel electrophoresis. PSI-LHCII megacomplex formation was found to require thylakoid stacking, and to depend upon growth light intensity and leaf age. These factors were, in turn, correlated with changes in PSI/PSII ratios and, intriguingly, PSI-LHCII megacomplex dynamics appeared to depend upon PSII core phosphorylation. These findings suggest new functions for PSI and a new level of regulation involving specialized subpopulations of photosystem I which have profound implications for current models of thylakoid dynamics.
光系统 II 是一种高度动态的多蛋白复合物，参与多种调节和修复过程。相比之下，光系统 I（PSI）直到最近才被认为是相对静态的。我们报告了植物 PSI-LHCII 超大复合物的发现，每个 PSI 反应中心含有多个 LHCII 三聚体。这些 PSI-LHCII 超大复合物对光强的变化反应迅速，如原生凝胶电泳所示。发现 PSI-LHCII 超大复合物的形成需要类囊体堆叠，并依赖于生长光强和叶片年龄。这些因素反过来又与 PSI/PSII 比值的变化相关，有趣的是，PSI-LHCII 超大复合物的动力学似乎取决于 PSII 核心磷酸化。这些发现为 PSI 提供了新的功能，并提出了一种新的调节方式，涉及到光系统 I 的专门亚群，这对当前的类囊体动力学模型具有深远的影响。
