A balanced PGR5 level is required for chloroplast development and optimum operation of cyclic electron transport around photosystem I
A balanced PGR5 level is required for chloroplast development and optimum operation of cyclic electron transport around photosystem I
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DOI：
10.1093/pcp/pcm116
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发表时间：
2007-10-01
影响因子：
4.9
通讯作者：
Shikanai, Toshiharu
中科院分区：
文献类型：
--
作者：
Okegawa, Yuki;Long, Terri A.;Shikanai, Toshiharu
PSI循环电子传递在开花植物的光合作用和光保护中起着重要作用。虽然类囊体蛋白PGR 5（质子梯度调节5）已被证明是必不可少的PSI循环电子传递的主要途径，其确切的功能仍然不清楚。在类囊体膜中过量积累PGR 5的转基因拟南芥中，叶绿体发育被延迟，尤其是在子叶中。虽然在稳态光合作用过程中光合电子传递不受影响，但在光条件转移后，会瞬时诱导高水平的非光化学猝灭（NPQ）。这种表型被解释为PSI循环电子传递，这是在体外系统中使用破裂的叶绿体，也在叶片中监测活动的升高。PGR 5的过度积累的影响是特异性的PSI循环电子传递的抗霉素A敏感途径，但不NAD（P）H脱氢酶（NDH）途径。我们建议，一个平衡的PGR 5水平是需要有效地调节抗霉素A敏感的PSI循环电子传递的速率，虽然PSI循环电子传递的速率可能也由其他因素在稳态光合作用调节。
PSI cyclic electron transport contributes markedly to photosynthesis and photoprotection in flowering plants. Although the thylakoid protein PGR5 (Proton Gradient Regulation 5) has been shown to be essential for the main route of PSI cyclic electron transport, its exact function remains unclear. In transgenic Arabidopsis plants overaccumulating PGR5 in the thylakoid membrane, chloroplast development was delayed, especially in the cotyledons. Although photosynthetic electron transport was not affected during steady-state photosynthesis, a high level of non-photochemical quenching (NPQ) was transiently induced after a shift of light conditions. This phenotype was explained by elevated activity of PSI cyclic electron transport, which was monitored in an in vitro system using ruptured chloroplasts, and also in leaves. The effect of overaccumulation of PGR5 was specific to the antimycin A-sensitive pathway of PSI cyclic electron transport but not to the NAD(P)H dehydrogenase (NDH) pathway. We propose that a balanced PGR5 level is required for efficient regulation of the rate of antimycin A-sensitive PSI cyclic electron transport, although the rate of PSI cyclic electron transport is probably also regulated by other factors during steady-state photosynthesis.