title: Supermolecular organization of photosystem II and its associated light-harvesting antenna in Arabidopsis thaliana.
abstract: The organization of Arabidopsis thaliana photosystem II (PSII) and its associated light-harvesting antenna (LHCII) was studied in isolated PSII-LHCII supercomplexes and native membrane-bound crystals by transmission electron microscopy and image analysis. Over 4000 single-particle projections of PSII-LHCII supercomplexes were analyzed. In comparison to spinach supercomplexes [Boekema, E.J., van Roon, H., van Breemen, J.F.L. & Dekker, J.P. (1999) Eur. J. Biochem. 266, 444-452] some striking differences were revealed: a much larger number of supercomplexes from Arabidopsis contain copies of M-type LHCII trimers. M-type trimers can also bind in the absence of the more common S-type trimers. No binding of l-type trimers could be detected. Analysis of native membrane-bound PSII crystals revealed a novel type of crystal with a unit cell of 25.6 x 21.4 nm (angle 77 degrees ), which is larger than any of the PSII lattices observed before. The data show that the unit cell is built up from C2S2M2 supercomplexes, rather than from C2S2M supercomplexes observed in native membrane crystals from spinach [Boekema, E.J., Van Breemen, J.F.L., Van Roon, H. & Dekker, J.P. (2000) J. Mol. Biol. 301, 1123-1133]. It is concluded from both the single particle analysis and the crystal analysis that the M-type trimers bind more strongly to PSII core complexes in Arabidopsis than in spinach.
authors.affiliation: Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh, Groningen, The Netherlands.
authors.forename: A E
authors.initials: AE
authors.lastname: Yakushevska
authors.forename: P E
authors.initials: PE
authors.lastname: Jensen
authors.forename: W
authors.initials: W
authors.lastname: Keegstra
authors.forename: H
authors.initials: H
authors.lastname: van Roon
authors.forename: H V
authors.initials: HV
authors.lastname: Scheller
authors.forename: E J
authors.initials: EJ
authors.lastname: Boekema
authors.forename: J P
authors.initials: JP
authors.lastname: Dekker
mesh_terms: D017360:Arabidopsis / Q000737:chemistry*; D003460:Crystallization; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D008958:Models, Molecular; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure*; D045332:Photosystem II Protein Complex; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D018724:Spinacia oleracea / Q000737:chemistry; D020524:Thylakoids / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D046911:Macromolecular Substances; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex