Comparative analysis of thylakoid protein complexes in state transition mutants nsi and stn7: focus on PSI and LHCII
Comparative analysis of thylakoid protein complexes in state transition mutants nsi and stn7: focus on PSI and LHCII
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DOI：
10.1007/s11120-020-00711-4
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发表时间：
2020-07-01
影响因子：
3.7
通讯作者：
Mulo, Paula
中科院分区：
文献类型：
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作者：
Koskela, Minna M.;Bruenje, Annika;Mulo, Paula
植物的光合机制可以通过平衡两个光系统（PS）之间的光捕获来适应光照条件的变化。这种驯化反应是由质体醌池氧化还原状态的变化引起的，这种状态通过STN7激酶的激活和随后的光收集复合物II （LHCII）蛋白的磷酸化引发状态转变。LHCII的磷酸化导致其与PSI（状态2）的关联，而去磷酸化则恢复PSII（状态1）的能量分配。除了磷酸化对状态转换的调节外，我们最近发现，缺乏叶绿体乙酰转移酶NSI的植物即使具有正常的LHCII磷酸化，也会被锁定在状态1。这种缺陷可能是由于一些叶绿体蛋白赖氨酸乙酰化程度降低所致。在这里，我们比较了通过Blue Native凝胶电泳分离的野生型（wt）、stn7和nsithylakoid蛋白复合物的组成。采用液相色谱-质谱联用iBAQ定量法测定蛋白复合物组成和相对蛋白丰度。我们发现，尽管存在明显的机制差异导致状态转换缺陷，但在突变体之间PSI和LHCII的组成没有发现重大差异。此外，与wt相比，stn7和nsii在波动光下都表现出生长迟缓和PSII能力下降，而在波动光下诱导的非光化学猝灭比instn7低得多。
The photosynthetic machinery of plants can acclimate to changes in light conditions by balancing light-harvesting between the two photosystems (PS). This acclimation response is induced by the change in the redox state of the plastoquinone pool, which triggers state transitions through activation of the STN7 kinase and subsequent phosphorylation of light-harvesting complex II (LHCII) proteins. Phosphorylation of LHCII results in its association with PSI (state 2), whereas dephosphorylation restores energy allocation to PSII (state 1). In addition to state transition regulation by phosphorylation, we have recently discovered that plants lacking the chloroplast acetyltransferase NSI are also locked in state 1, even though they possess normal LHCII phosphorylation. This defect may result from decreased lysine acetylation of several chloroplast proteins. Here, we compared the composition of wild type (wt),stn7andnsithylakoid protein complexes involved in state transitions separated by Blue Native gel electrophoresis. Protein complex composition and relative protein abundances were determined by LC-MS/MS analyses using iBAQ quantification. We show that despite obvious mechanistic differences leading to defects in state transitions, no major differences were detected in the composition of PSI and LHCII between the mutants. Moreover, bothstn7andnsiplants show retarded growth and decreased PSII capacity under fluctuating light as compared to wt, while the induction of non-photochemical quenching under fluctuating light was much lower in bothnsimutants than instn7.