tailieunhanh - Báo cáo Y học: Supermolecular organization of photosystem II and its associated light-harvesting antenna in Arabidopsis thaliana

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, ., van Roon, H., van Breemen, . & Dekker, . (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 | Eur. J. Biochem. 268 6020-6028 2001 FEBS 2001 Supermolecular organization of photosystem II and its associated light-harvesting antenna in Arabidopsis thaliana Alevtyna E. Yakushevska1 Poul E. Jensen2 Wilko Keegstra1 Henny van Roon3 Henrik V. Scheller2 Egbert J. Boekema1 and Jan P. Dekker3 1 Department of Biophysical Chemistry Groningen Biomolecular Sciences and Biotechnology Institute University of Groningen Nijenborgh Groningen the Netherlands 2Plant Biochemistry Laboratory Department of Plant Biology The Royal Veterinary and Agricultural University Copenhagen Denmark 3 Faculty of Sciences Division of Physics and Astronomy Vrije Universiteit Amsterdam the Netherlands 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 . van Roon H. van Breemen . Dekker . 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 X nm angle 77 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 . Van Breemen . van Roon H. Dekker . 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 .