Isolation of novel PSII-LHCII megacomplexes from pea plants characterized by a combination of proteomics and electron microscopy
Isolation of novel PSII-LHCII megacomplexes from pea plants characterized by a combination of proteomics and electron microscopy
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DOI：
10.1007/s11120-016-0216-3
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发表时间：
2016-12-01
影响因子：
3.7
通讯作者：
Pagliano, Cristina
中科院分区：
文献类型：
--
作者：
Albanese, Pascal;Nield, Jon;Pagliano, Cristina
在高等植物中，光系统II(PSII)是嵌入叶绿体类囊体膜中的多亚单位色素-蛋白质复合体，在叶绿体膜中主要以二聚体形式存在于基粒中。它的捕光天线系统LHCII由三聚体和单体络合物组成，这些络合物可以与二聚体PSII核心络合物发生不同数量的缔合，形成不同类型的PSII-LHCII超络合物。此外，PSII-LHCII超复合体可以横向结合在类囊体膜平面内，从而形成更高分子质量的复合体，称为PSII-LHCII巨复合体(Boekema等人。1999a，生物化学38：2233-2239；Boekema等人。1999年b，欧洲生物化学杂志266：444-452)。在这项研究中，直接从堆叠的豌豆类囊体膜中分离出PSII-LHCII巨复合体，用洗涤剂n-十二烷基α-d-麦芽糖苷快速一步增溶，然后蔗糖梯度超速离心。对这些大型复合体进行了生化和结构分析。与以前的研究相比，在负染样本上的透射电子显微镜，随后的单颗粒分析，揭示了一种新形式的PSII-LHCII巨型复合体(Boekema等人，1999a，在生物化学38：2233-2239中；Boekema等人)。1999b，在EUJ Biochem 266：444-452中)，由两个PSII-LHCII超复合体在膜平面上并排坐在一起，与第二个副本夹在一起。这个巨型复合体的第二个副本很可能来自于颗粒堆叠的相反膜。根据(Dekker and Boekema 2005 Biochim BiPhys Acta 1706：12-39)，观察到了两种完整的夹心巨型复合体，并将其命名为(C2S2)(4)和(C2S2+C2S2M2)(2)巨型复合体。通过应用基于凝胶的蛋白质组学方法，对分离的巨型复合体的蛋白质组成进行了充分的表征。综上所述，分离的巨型复合体的新结构形式和相关的建模为PSII-LHCII超复合体如何相互结合提供了新的见解，不仅在膜平面，而且在叶绿体内的颗粒堆叠之间。
In higher plants, photosystem II (PSII) is a multi-subunit pigment-protein complex embedded in the thylakoid membranes of chloroplasts, where it is present mostly in dimeric form within the grana. Its light-harvesting antenna system, LHCII, is composed of trimeric and monomeric complexes, which can associate in variable number with the dimeric PSII core complex in order to form different types of PSII-LHCII supercomplexes. Moreover, PSII-LHCII supercomplexes can laterally associate within the thylakoid membrane plane, thus forming higher molecular mass complexes, termed PSII-LHCII megacomplexes (Boekema et al. 1999a, in Biochemistry 38:2233-2239; Boekema et al. 1999b, in Eur J Biochem 266:444-452). In this study, pure PSII-LHCII megacomplexes were directly isolated from stacked pea thylakoid membranes by a rapid single-step solubilization, using the detergent n-dodecyl-alpha-d-maltoside, followed by sucrose gradient ultracentrifugation. The megacomplexes were subjected to biochemical and structural analyses. Transmission electron microscopy on negatively stained samples, followed by single-particle analyses, revealed a novel form of PSII-LHCII megacomplexes, as compared to previous studies (Boekema et al.1999a, in Biochemistry 38:2233-2239; Boekema et al. 1999b, in Eur J Biochem 266:444-452), consisting of two PSII-LHCII supercomplexes sitting side-by-side in the membrane plane, sandwiched together with a second copy. This second copy of the megacomplex is most likely derived from the opposite membrane of a granal stack. Two predominant forms of intact sandwiched megacomplexes were observed and termed, according to (Dekker and Boekema 2005 Biochim Biophys Acta 1706:12-39), as (C2S2)(4) and (C2S2 + C2S2M2)(2) megacomplexes. By applying a gel-based proteomic approach, the protein composition of the isolated megacomplexes was fully characterized. In summary, the new structural forms of isolated megacomplexes and the related modeling performed provide novel insights into how PSII-LHCII supercomplexes may bind to each other, not only in the membrane plane, but also between granal stacks within the chloroplast.