Figure 8.

Schematic representation of proposed models of the PSUs in other photosynthetic systems. The figure displays inter- and extramembrane light-harvesting complexes, together with the RCs (RC in green bacteria, and PS-I and PS-II in cyanobacteria, dinoflagellates, and green plants). (a) Green bacteria: The major light-harvesting complex, chlorosome, contains rod-like BChl c aggregates surrounded by a layer of protein embedding lipids. Excitation energy harvested by the rod-like aggregates reaches the RC through a BChls a containing baseplate and membrane-bound light-harvesting BChl a complexes. (b) Cyanobacteria: The dominant light-harvesting complex of cyanobacteria and red algae, phycobilisome (PBS), is unique in choosing linear tetrapyrroles as pigments. Several types of disk-like pigment–protein complexes such as R-phycoerythrin (51) constitute the phycobilisome rods and core. (c) Dinoflagellates: The photosynthetic unit of dinoflagellates consists of several membrane-bound pigment–protein complexes and an extramembrane light-harvesting complex, the peridinin–chlorophyll–protein (PCP). (d) Green plants: Chloroplasts of green plants possess chlorophyll-carotenoid containing LHCII (6) as the most abundant light-harvesting complex. [Images of R-phycoerythrin and PCP were produced with the program vmd (25)].