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. Author manuscript; available in PMC: 2020 Feb 22.
Published in final edited form as: Annu Rev Biophys. 2019 May 6;48:395–419. doi: 10.1146/annurev-biophys-052118-115259

Figure 3.

Figure 3

Natural photosynthetic light-harvesting systems. (a) Schematic representation of a light-harvesting complex in the green sulfur bacterium. Chlorosomes have high-absorption cross sections that harvest light and transfer energy to the Fenna-Matthews-Olson (FMO) complex through the baseplate. Absorbed energy is then transferred to reaction centers. (b) Illustrative representation of the phycobilisome light-harvesting antennae. Bilin-containing proteins, phycoerythrin, phycocyanin, and allophycocyanin, absorb light in the green, orange, and red regions of the visible light spectrum. The energy-transfer cascade from the phycoerythrin to allophycocyanin via phycocyanin funnels the energy to the photosystem I and II reaction centers (59, 60, 119). (c) Protein scaffolds in the FMO control the spatial organization and influence the site energies of bacteriochlorophyll pigments (184) [Protein Data Bank identification (PDB ID) 3EOJ]. (d) The light-harvesting complex (LH2) in purple bacteria has a characteristic circular structure, which contains the B800 and B850 rings (PDB ID 2FKW) (31). Proteins control the spatial organization of bacteriochlorophyll pigments in the B800 and B850 rings. These different organizations lead to exciton delocalization (118) and fast energy transfer (105).