Lack of the light-harvesting complex CP24 affects the structure and function of the grana membranes of higher plant chloroplasts
Lack of the light-harvesting complex CP24 affects the structure and function of the grana membranes of higher plant chloroplasts
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DOI：
10.1105/tpc.106.045641
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发表时间：
2006-11-01
期刊：
影响因子：
11.6
通讯作者：
Horton, Peter
中科院分区：
文献类型：
--
作者：
Kovacs, Laszlo;Damkjaer, Jakob;Horton, Peter
高等植物的光系统II(PSII)捕光天线含有许多功能未知的高度保守的基因产物。对其中一种CP24捕光复合体耗尽的拟南芥植株进行了分析。缺乏CP24的植株表现出光限光合速率和生长的下降，但类囊体膜的色素和蛋白质含量在其他方面几乎没有变化。然而，这些膜中PSII的宏观结构发生了重大变化；电子显微镜和图像分析显示，野生植物中完全不存在以C2S2M2捕光复合体II(LHCII)/PSII超复合体为主的超复合体。相反，只有缺乏LHCIIb M-三聚体的C2S2超络合物被发现。光谱分析证实了PSII野生型宏观结构的破坏。结果发现，PSII天线的功能受到干扰：PSII中心之间的连通性降低，最大光化学产率降低；快速可逆的非光化学猝灭被抑制；状态转换发生动力学改变。因此，CP24是决定PSII捕光天线结构和功能的重要因素，为M-三聚体与PSII复合体的结合提供了连接物，允许特定的宏观组织，这是实现最大量子效率和光保护性分散过剩激发能量所必需的。
The photosystem II (PSII) light-harvesting antenna in higher plants contains a number of highly conserved gene products whose function is unknown. Arabidopsis thaliana plants depleted of one of these, the CP24 light-harvesting complex, have been analyzed. CP24-deficient plants showed a decrease in light-limited photosynthetic rate and growth, but the pigment and protein content of the thylakoid membranes were otherwise almost unchanged. However, there was a major change in the macroorganization of PSII within these membranes; electron microscopy and image analysis revealed the complete absence of the C2S2M2 light-harvesting complex II (LHCII)/PSII supercomplex predominant in wild-type plants. Instead, only C2S2 supercomplexes, which are deficient in the LHCIIb M-trimers, were found. Spectroscopic analysis confirmed the disruption of the wild-type macroorganization of PSII. It was found that the functions of the PSII antenna were disturbed: connectivity between PSII centers was reduced, and maximum photochemical yield was lowered; rapidly reversible non-photochemical quenching was inhibited; and the state transitions were altered kinetically. CP24 is therefore an important factor in determining the structure and function of the PSII light-harvesting antenna, providing the linker for association of the M-trimer into the PSII complex, allowing a specific macroorganization that is necessary both for maximum quantum efficiency and for photoprotective dissipation of excess excitation energy.