Albanese Pascal, Manfredi Marcello, Meneghesso Andrea, Marengo Emilio, Saracco Guido, Barber James, Morosinotto Tomas, Pagliano Cristina
Applied Science and Technology Department-BioSolar Lab, Politecnico di Torino, Viale T. Michel 5, 15121, Alessandria, Italy; Department of Biology, University of Padova, Via Ugo Bassi 58 B, 35121 Padova, Italy.
ISALIT-Department of Science and Technological Innovation, University of Eastern Piedmont, Viale T. Michel 11, 15121 Alessandria, Italy; Department of Science and Technological Innovation, University of Eastern Piedmont, Viale T. Michel 11, 15121 Alessandria, Italy.
Biochim Biophys Acta. 2016 Oct;1857(10):1651-60. doi: 10.1016/j.bbabio.2016.06.011. Epub 2016 Jul 1.
Plants are sessile organisms and need to acclimate to ever-changing light conditions in order to survive. These changes trigger a dynamic reorganization of the membrane protein complexes in the thylakoid membranes. Photosystem II (PSII) and its light harvesting system (LHCII) are the major target of this acclimation response, and accumulating evidences indicate that the amount and composition of PSII-LHCII supercomplexes in thylakoids are dynamically adjusted in response to changes in light intensity and quality. In this study, we characterized the PSII-LHCII supercomplexes in thylakoid membranes of pea plants in response to long-term acclimation to different light intensities. We provide evidence of a reorganization of the PSII-LHCII supercomplexes showing distinct changes in their antenna moiety. Mass spectrometry analysis revealed a specific reduction of Lhcb3, Lhcb6 and M-LHCII trimers bound to the PSII cores, while the Lhcb4.3 isoform increased in response to high light intensities. The modulation of Lhcb protein content correlates with the reduction of the functional PSII antenna size. These results suggest that the Lhcb3, Lhcb4.3 and Lhcb6 antenna subunits are major players in modulation of the PSII antenna size upon long-term acclimation to increased light levels. PsbS was not detected in the isolated PSII-LHCII supercomplexes at any light condition, despite an increased accumulation in thylakoids of high light acclimated plants, suggesting that PsbS is not a constitutive component of PSII-LHCII supercomplexes.
植物是固着生物，为了生存需要适应不断变化的光照条件。这些变化会引发类囊体膜中膜蛋白复合物的动态重组。光系统II（PSII）及其捕光系统（LHCII）是这种适应性反应的主要靶点，越来越多的证据表明，类囊体中PSII-LHCII超复合物的数量和组成会根据光照强度和质量的变化而动态调整。在本研究中，我们对豌豆植物类囊体膜中的PSII-LHCII超复合物进行了表征，以研究其对不同光照强度的长期适应情况。我们提供了PSII-LHCII超复合物重组的证据，表明其天线部分发生了明显变化。质谱分析显示，与PSII核心结合的Lhcb3、Lhcb6和M-LHCII三聚体有特定程度的减少，而Lhcb4.3亚型在高光强度下增加。Lhcb蛋白含量的调节与功能性PSII天线大小的减小相关。这些结果表明，在长期适应光照增强的过程中，Lhcb3、Lhcb4.3和Lhcb6天线亚基是调节PSII天线大小的主要因素。在任何光照条件下，分离出的PSII-LHCII超复合物中均未检测到PsbS，尽管高光适应植物的类囊体中PsbS的积累有所增加，这表明PsbS不是PSII-LHCII超复合物的组成成分。
