Isolation of novel PSII-LHCII megacomplexes from pea plants characterized by a combination of proteomics and electron microscopy
| Autor: | Emilio Marengo, Jose Alejandro Muñoz Tabares, Marcello Manfredi, Cristina Pagliano, James Barber, Pascal Albanese, Jon Nield, Guido Saracco, Angelica Chiodoni, Fabio Gosetti |
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| Přispěvatelé: | Albanese, P, Nield, J, Tabares, J, Chiodoni, A, Manfredi, M, Gosetti, F, Marengo, E, Saracco, G, Barber, J, Pagliano, C |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Proteomics
0301 basic medicine PSII-LHCII megacomplex Photosystem II Light-Harvesting Protein Complexes Plant Science Biology Electron Biochemistry Single-particle analysi Mass Spectrometry law.invention 03 medical and health sciences chemistry.chemical_compound Electrophoresi CHIM/01 - CHIMICA ANALITICA Microscopy Electron Transmission law Transmission Microscopy Polyacrylamide Gel Molecular mass Pea Peas Proteomic Photosystem II Protein Complex Cell Biology General Medicine Chloroplast Microscopy Electron 030104 developmental biology Membrane Monomer chemistry Light-Harvesting Protein Complexe Thylakoid Biophysics Electrophoresis Polyacrylamide Gel Ultracentrifuge Electron microscope Transmission electron microscopy |
| Popis: | 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-α-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. |
| Databáze: | OpenAIRE |
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