Molecular Architecture of Plant Thylakoids under Physiological and Light Stress Conditions: A Study of Lipid-Light-Harvesting Complex II Model Membranes
Molecular Architecture of Plant Thylakoids under Physiological and Light Stress Conditions: A Study of Lipid-Light-Harvesting Complex II Model Membranes
复制标题
DOI：
10.1105/tpc.113.113076
复制
发表时间：
2013-06-01
期刊：
影响因子：
11.6
通讯作者：
Gruszecki, Wieslaw I.
中科院分区：
文献类型：
--
作者：
Janik, Ewa;Bednarska, Joanna;Gruszecki, Wieslaw I.
在这项研究中，我们分析了由光合作用捕光复合体II(LHCII；从菠菜中分离出来)和植物脂类单半乳糖基二酰甘油和双半乳糖基二酰甘油组成的多层脂蛋白膜。分析了两种色素-蛋白质复合体：从暗适应叶片分离的色素-蛋白质复合体(LHCII)和从强光预照的叶片中分离的色素-蛋白质复合体(LHCII-HL)。LHCII-HL络合物部分被磷酸化，并含有玉米黄质。X-射线衍射、红外成像显微镜、激光共聚焦扫描显微镜和透射电子显微镜的结果表明，脂质-LHCII膜组装成平面多层膜，而脂质-LHCII-HL膜形成的有序性较差。在这两个系统中，蛋白质都形成了超分子结构。在LHCII-HL中，这些结构横跨多层膜，垂直于膜平面，而在LHCII中，这些结构是层状的，位于膜的平面内。荧光寿命成像显微镜显示，LHCII-HL的层状聚集体在激发能量猝灭方面特别活跃。两种结构都是通过分子间氢键稳定的。我们的结论是，LHCII跨层、铆钉状结构的形成是类囊体粒细胞结构自发形成和稳定的重要决定因素，因为片状聚集体非常适合在过激发时耗散过剩能量。
In this study, we analyzed multibilayer lipid-protein membranes composed of the photosynthetic light-harvesting complex II (LHCII; isolated from spinach [Spinacia oleracea]) and the plant lipids monogalcatosyldiacylglycerol and digalactosyldiacylglycerol. Two types of pigment-protein complexes were analyzed: those isolated from dark-adapted leaves (LHCII) and those from leaves preilluminated with high-intensity light (LHCII-HL). The LHCII-HL complexes were found to be partially phosphorylated and contained zeaxanthin. The results of the x-ray diffraction, infrared imaging microscopy, confocal laser scanning microscopy, and transmission electron microscopy revealed that lipid-LHCII membranes assemble into planar multibilayers, in contrast with the lipid-LHCII-HL membranes, which form less ordered structures. In both systems, the protein formed supramolecular structures. In the case of LHCII-HL, these structures spanned the multibilayer membranes and were perpendicular to the membrane plane, whereas in LHCII, the structures were lamellar and within the plane of the membranes. Lamellar aggregates of LHCII-HL have been shown, by fluorescence lifetime imaging microscopy, to be particularly active in excitation energy quenching. Both types of structures were stabilized by intermolecular hydrogen bonds. We conclude that the formation of trans-layer, rivet-like structures of LHCII is an important determinant underlying the spontaneous formation and stabilization of the thylakoid grana structures, since the lamellar aggregates are well suited to dissipate excess energy upon overexcitation.