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)].