SPECIFIC ASSOCIATION OF PHOTOSYSTEM-II AND LIGHT-HARVESTING COMPLEX-II IN PARTIALLY SOLUBILIZED PHOTOSYSTEM-II MEMBRANES

In this study, me report the structural characterization of photosyste m II complexes obtained from partially solubilized photosystem II memb ranes. Direct observation by electron microscopy, within a few minutes after a mild disruption of the membranes with the detergent n-dodecyl -alpha,D-maltoside, revealed the presence of several large supramolecu lar complexes. Images of these complexes were subjected to multivariat e statistical analysis and classification procedures, resolving a new complex consisting of the previously characterized dimeric supercomple x of photosystem II and light-harvesting complex II [Boekema et al., P roc. Natl. Acad. Sci. USA 92 (1995) 175-179] and two additional, symme trically organized protein masses each containing a second type of tri meric light-harvesting II complex. We conclude that large and labile i ntegral membrane proteins, such. as photosystem II, can be quickly str ucturally characterized without extensive purification. (C) 1998 Feder ation of European Biochemical Societies.