Specific association of photosystem II and light‐harvesting complex II in partially solubilized photosystem II membranes

Abstract

In this study, we report the structural characterization of photosystem II complexes obtained from partially solubilized photosystem II membranes. Direct observation by electron microscopy, within a few minutes after a mild disruption of the membranes with the detergent n-dodecyl-K K,D-maltoside, revealed the presence of several large supramolecular complexes. Images of these complexes were subjected to multivariate statistical analysis and classification procedures, resolving a new complex consisting of the previously characterized dimeric supercomplex of photosystem II and light-harvesting complex II [Boekema et al., Proc. Natl. Acad. Sci. USA 92 (1995) 175^179] and two additional, symmetrically organized protein masses each containing a second type of trimeric light-harvesting II complex. We conclude that large and labile integral membrane proteins, such as photosystem II, can be quickly structurally characterized without extensive purification.z 1998 Federation of European Biochemical Societies.

Antisense Inhibition of the Photosynthetic Antenna Proteins CP29 and CP26: Implications for the Mechanism of Protective Energy Dissipation

“…One role that has been suggested for CP26 and CP29 is that of organizing the major LHCII light-harvesting antenna of PSII; therefore, it might be expected that the loss of one of these complexes could alter the antenna properties of individual PSII units. The significant reduction in PSII antenna size in CP26 antisense lines, by approximately a full LHCII trimer in both LL and HL growth conditions, is consistent with this hypothesis; we suggest that CP26 may be the primary anchor point for the strongly bound or proximal (nonmobile) LHCII (Mäenpää and Andersson, 1989;Spangfort and Andersson, 1989;Boekema et al, 1998) and that the loss of CP26 prevents the binding of this population of LHCII complexes. Conversely, CP29 and/or CP24 may be the principal site for binding of the distal LHCII (Mäenpää and Andersson, 1989), which is present is significant amounts only during LL growth ).…”

Molecular Configuration of Xanthophyll Cycle Carotenoids in Photosystem II Antenna Complexes

“…This enables us to estimate their thickness to be about 6 nm, indicating single layers of LHCII. Because the isolation procedure also yielded monomeric PSII core complexes and some fraction of the minor antenna components, it is feasible that the detergent has selectively solubilized central parts of the PSII supercomplex (14) leaving intact tetrads of associated trimers and oligomeric peripheral antenna (15,16).…”

Supermolecular structure of photosystem II and location of the PsbS protein

“…We believe that these chlorophyll a/b binding proteins and many of those in fraction three are located in regions that interconnect the LHC II^PS II supercomplex. Indeed, the recent work of Boekema et al (1998Boekema et al ( , 1999 indicates that the LHC II^PS II supercomplex shown in ¢gure 7 is interconnected by trimers of LHC II with CP24, possibly acting as a linker (Bassi & Dainese 1992). Given that on average there are about 250 chlorophylls per PS II reaction centre, this would mean that for every supercomplex there are about four to ¢ve trimers of LHC II.…”