The role of PGR5 in the redox poising of photosynthetic electron transport
The role of PGR5 in the redox poising of photosynthetic electron transport
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DOI：
10.1016/j.bbabio.2007.07.007
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发表时间：
2007-10-01
影响因子：
4.3
通讯作者：
Johnson, Giles N.
中科院分区：
文献类型：
--
作者：
Nandha, Beena;Finazzi, Giovanni;Johnson, Giles N.
拟南芥的PGR 5突变体被描述为缺乏围绕光系统1的循环电子流，然而，PGR 5蛋白的确切作用仍然未知。为了解决这个问题，在pgr 5和野生型A的完整叶片中检查光合电子传递。thaliana.基于在DCMU存在下，P700在远红光下氧化和氧化后再还原的动力学测量，我们得出结论，该突变体能够以与野生型相似的速率进行循环电子流。因此，PGR 5蛋白对于循环流动不是必需的。然而，循环流的pgr 5突变的条件下，这一过程通常是在野生型叶增强，即高光或低CO2浓度导致增强循环电子流的影响。这表明不同的能力来调节循环流在响应环境刺激的突变体。我们还表明，pgr5突变体在叶绿体的氧化还原平衡中受到影响，在大多数条件下电子传递链大幅减少。这可能会导致在某些条件下光合电子传递的反馈调节缺陷，从而提供了一个合理的循环电子流的效率降低。(C)2007 Elsevier B.V.保留所有权利。
The pgr5 mutant of Arabidopsis thaliana has been described as being deficient in cyclic electron flow around photosystem 1, however, the precise role of the PGR5 protein remains unknown. To address this issue, photosynthetic electron transport was examined in intact leaves of pgr5 and wild type A. thaliana. Based on measurements of the kinetics of P700 oxidation in far red light and re-reduction following oxidation in the presence of DCMU, we conclude that this mutant is able to perform cyclic electron flow at a rate similar to the wild type. The PGR5 protein is therefore not essential for cyclic flow. However, cyclic flow is affected by the pgr5 mutation under conditions where this process is normally enhanced in wild type leaves, i.e. high light or low CO2 concentrations resulted in enhancement of cyclic electron flow. This suggests a different capacity to regulate cyclic flow in response to environmental stimuli in the mutant. We also show that the pgr5 mutant is affected in the redox poising of the chloroplast, with the electron transport chain being substantially reduced under most conditions. This may result in defective feedback regulation of photosynthetic electron transport under some conditions, thus providing a rationale for the reduced efficiency of cyclic electron flow. (C) 2007 Elsevier B.V. All rights reserved.