Queen Mary, University of London, School of Biological and Chemical Sciences, London, UK.
Plant Cell Environ. 2012 Feb;35(2):347-59. doi: 10.1111/j.1365-3040.2011.02349.x. Epub 2011 Jun 28.
State transitions and photosystem stoichiometry adjustment are two oxidation-reduction (redox)-regulated acclimatory responses in photosynthesis. State transitions are short-term adaptations that, in chloroplasts, involve reversible post-translational modification by phosphorylation of light-harvesting complex II (LHC II). Photosystem stoichiometry adjustments are long-term responses involving transcriptional regulation of reaction centre genes. Both responses are initiated by changes in light quality and are regulated by the redox state of plastoquinone (PQ). The LHC II kinase involved in the state 2 transition is a serine/threonine kinase known as STT7 in Chlamydomonas, and as STN7 in Arabidopsis. The phospho-LHC II phosphatase that produces the state 1 transition is a PP2C-type protein phosphatase currently termed both TAP38 and PPH1. In plants and algae, photosystem stoichiometry adjustment is governed by a modified two-component sensor kinase of cyanobacterial origin - chloroplast sensor kinase (CSK). CSK is a sensor of the PQ redox state. Chloroplast sigma factor 1 (SIG1) and plastid transcription kinase (PTK) are the functional partners of CSK in chloroplast gene regulation. We suggest a signalling pathway for photosystem stoichiometry adjustment. The signalling pathways of state transitions and photosystem stoichiometry adjustments are proposed to be distinct, with the two pathways sensing PQ redox state independently of each other.
状态转变和光系统化学计量比的调整是光合作用中两种氧化还原（redox）调节的适应反应。状态转变是一种短期适应，涉及通过光捕获复合物 II（LHC II）的磷酸化进行可逆的翻译后修饰。光系统化学计量比的调整是长期反应，涉及反应中心基因的转录调控。这两种反应都是由光质的变化引发的，并受到质体醌（PQ）的氧化还原状态的调节。涉及状态 2 转变的 LHC II 激酶是一种丝氨酸/苏氨酸激酶，在衣藻中称为 STT7，在拟南芥中称为 STN7。产生状态 1 转变的磷酸化 LHC II 磷酸酶是一种 PP2C 型蛋白磷酸酶，目前称为 TAP38 和 PPH1。在植物和藻类中，光系统化学计量比的调整受来源于蓝细菌的改良双组分传感器激酶-叶绿体传感器激酶（CSK）的控制。CSK 是 PQ 氧化还原状态的传感器。叶绿体 sigma 因子 1（SIG1）和质体转录激酶（PTK）是 CSK 在叶绿体基因调控中的功能伙伴。我们提出了一种光系统化学计量比调整的信号通路。状态转变和光系统化学计量比调整的信号通路被认为是不同的，两条通路独立地感知 PQ 的氧化还原状态。
