Dissociation of Light-Harvesting Complex II from Photosystem II During State Transitions in Chlamydomonas reinhardtii
Dissociation of Light-Harvesting Complex II from Photosystem II During State Transitions in Chlamydomonas reinhardtii
复制标题
DOI：
10.1007/978-1-4020-6709-9_222
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Masakazu Iwai;J. Minagawa
中科院分区：
文献类型：
--
作者：
Masakazu Iwai;J. Minagawa
状态转换是调节光系统I （PSI）和光系统II （PSII）光驱动激发平衡的一种植物光驯化机制。人们认为，光收集复合物（LHC） II的再分配调节了每个光系统的吸收截面。最近，通过分离PSI、LHCI和LHCII组成的蛋白质超复合体，提供了LHCII与PSI关联的几条生化证据。然而，lhcii与PSII的分离（在状态转变过程中应该同时发生）仍不清楚。在这项研究中，我们建立了一个流线型的方案来分离由PSII和LHCII组成的蛋白质超复合体，即所谓的PSII-LHCII超复合体，以探讨其在莱茵衣藻状态转变过程中的结构变化。结果表明，状态1的PSII-LHCII超配合物形成了一个分子量约为1,500 kDa的二聚体。我们推测，在过渡到状态2的过程中，PSII-LHCII超络合物首先发生单体化，随后LHCII与PSII分离，这伴随着LHCII的磷酸化。
State transition is a plant photoacclimation mechanism to regulate the equilibrium of the light-driven excitation at photosystem I (PSI) and photosystem II (PSII). It has been considered that redistribution of light-harvesting complex (LHC) II adjusts the absorption-cross section of each photosystem. Several lines of biochemical evidence for the association of LHCII to PSI were recently provided by isolating a protein supercomplex composed of PSI, LHCI, and LHCII. However, the detachment of LHCIIs from PSII, which should occur simultaneously during state transitions, still remains unclear. In this study, we established a streamlined protocol to isolate a protein supercomplex comprised of PSII and LHCII, a so-called PSII-LHCII supercomplex, to explore the changes in its structure during state transitions inChlamydomonas reinhardtii. The results suggested that the PSII-LHCII supercomplex in state 1 formed a dimer with the molecular weight of around 1,500 kDa. We speculate that, in the course of a transition to State 2, monomerization of the PSII-LHCII supercomplex occurs first, and subsequently the detachment of LHCII from PSII takes\ place, which is accompanied by the phosphorylation of LHCIIs.