PsbP protein, but not PsbQ protein, is essential for the regulation and stabilization of photosystem II in higher plants
PsbP protein, but not PsbQ protein, is essential for the regulation and stabilization of photosystem II in higher plants
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DOI：
10.1104/pp.105.068643
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发表时间：
2005-11-01
期刊：
影响因子：
7.4
通讯作者：
Sato, F
中科院分区：
文献类型：
--
作者：
Ifuku, K;Yamamoto, Y;Sato, F
PSBP和PsbQ蛋白是光系统II(PSII)的外在亚基，参与光合作用水氧化的正常功能。这两种蛋白质广泛存在于光合作用生物体内，然而，它们在高等植物中的生理作用还没有很好地确定。在本研究中，我们建立并分析了通过RNA干扰技术严重下调PSBP或PsbQ水平的转基因烟草植株。与野生型植物相比，缺乏PsbQ的植物没有表现出特定的表型。这表明，在正常生长条件下，高等植物体内的PsbQ是不必要的。另一方面，缺乏PSBP的植株表现出显著的表型：生长严重减慢，叶片呈淡绿色，PS II的量子效率显著下降。在PSBP缺乏的植物中，大部分PSII核心亚基在类囊体内积累，而在体外需要PSBP与PSII结合的PsbQ显著减少。没有PSBP的PSII对光敏感，当损伤的PSII的修复过程被氯霉素抑制时，PSII迅速失活。此外，热释光研究表明，在PSBP缺乏的叶片中，催化锰团簇明显不稳定，在黑暗中很容易分解。目前的结果表明，PSBP而不是PsbQ是高等植物体内正常PSII功能所必需的。
PsbP and PsbQ proteins are extrinsic subunits of photosystem II (PSII) and participate in the normal function of photosynthetic water oxidation. Both proteins exist in a broad range of the oxygenic photosynthetic organisms; however, their physiological roles in vivo have not been well defined in higher plants. In this study, we established and analyzed transgenic tobacco (Nicotiana tabacum) plants in which the levels of PsbP or PsbQ were severely down-regulated by the RNA interference technique. A plant that lacked PsbQ showed no specific phenotype compared to a wild-type plant. This suggests that PsbQ in higher plants is dispensable under the normal growth condition. On the other hand, a plant that lacked PsbP showed prominent phenotypes: drastic retardation of growth, pale-green-colored leaves, and a marked decrease in the quantum yield of PSII evaluated by chlorophyll fluorescence. In PsbP-deficient plant, most PSII core subunits were accumulated in thylakoids, whereas PsbQ, which requires PsbP to bind PSII in vitro, was dramatically decreased. PSII without PsbP was hypersensitive to light and rapidly inactivated when the repair process of the damaged PSII was inhibited by chloramphenicol. Furthermore, thermoluminescence studies showed that the catalytic manganese cluster in PsbP-deficient leaves was markedly unstable and readily disassembled in the dark. The present results demonstrated that PsbP, but not PsbQ, is indispensable for the normal PSII function in higher plants in vivo.