Tikhonov Alexander N, Vershubskii Alexey V
Faculty of Physics, Moscow State University, Moscow, Russia, 119991.
Photosynth Res. 2017 Sep;133(1-3):103-114. doi: 10.1007/s11120-017-0349-z. Epub 2017 Mar 8.
In chloroplasts, photosynthetic electron transport complexes interact with each other via the mobile electron carriers (plastoquinone and plastocyanin) which are in surplus amounts with respect to photosystem I and photosystem II (PSI and PSII), and the cytochrome b f complex. In this work, we analyze experimental data on the light-induced redox transients of photoreaction center P in chloroplasts within the framework of our mathematical model. This analysis suggests that during the action of a strong actinic light, even significant attenuation of PSII [for instance, in the result of inhibition of a part of PSII complexes by DCMU or due to non-photochemical quenching (NPQ)] will not cause drastic shortage of electron flow through PSI. This can be explained by "electronic" and/or "excitonic" connectivity between different PSII units. At strong AL, the overall flux of electrons between PSII and PSI will maintain at a high level even with the attenuation of PSII activity, provided the rate-limiting step of electron transfer is beyond the stage of PQH formation. Results of our study are briefly discussed in the context of NPQ-dependent mechanism of chloroplast protection against light stress.
在叶绿体中，光合电子传递复合体通过移动电子载体（质体醌和质体蓝素）相互作用，相对于光系统I和光系统II（PSI和PSII）以及细胞色素b6f复合体而言，这些移动电子载体的数量过剩。在这项工作中，我们在数学模型的框架内分析了叶绿体中光反应中心P的光诱导氧化还原瞬变的实验数据。该分析表明，在强光照射期间，即使PSII显著衰减[例如，由于DCMU抑制了一部分PSII复合体或由于非光化学猝灭（NPQ）]，也不会导致通过PSI的电子流严重短缺。这可以通过不同PSII单元之间的“电子”和/或“激子”连接来解释。在强光照射下，即使PSII活性衰减，只要电子转移的限速步骤超过PQH形成阶段，PSII和PSI之间的电子总通量仍将维持在较高水平。我们在叶绿体依赖NPQ的光胁迫保护机制的背景下简要讨论了我们的研究结果。
