title: Evolution of flexible non-photochemical quenching mechanisms that regulate light harvesting in oxygenic photosynthesis.
abstract: All photosynthetic organisms need to regulate light harvesting for photoprotection. Three types of flexible non-photochemical quenching (NPQ) mechanisms have been characterized in oxygenic photosynthetic cyanobacteria, algae, and plants: OCP-, LHCSR-, and PSBS-dependent NPQ. OCP-dependent NPQ likely evolved first, to quench excess excitation in the phycobilisome (PB) antenna of cyanobacteria. During evolution of eukaryotic algae, PBs were lost in the green and secondary red plastid lineages, while three-helix light-harvesting complex (LHC) antenna proteins diversified, including LHCSR proteins that function in dissipating excess energy rather than light harvesting. PSBS, an independently evolved member of the LHC protein superfamily, seems to have appeared exclusively in the green lineage, acquired a function as a pH sensor that turns on NPQ, and eventually replaced LHCSR in vascular plants.
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720-3102, USA. niyogi@berkeley.edu
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Niyogi
authors.forename: Thuy B
authors.initials: TB
authors.lastname: Truong
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D005075:Biological Evolution; D044002:Bryophyta / Q000502:physiology; D000458:Cyanobacteria / Q000502:physiology*; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D045524:Phycobilisomes / Q000378:metabolism; D018521:Plant Physiological Phenomena; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D045524:Phycobilisomes; D010940:Plant Proteins; C109473:orange carotenoid protein, Synechocystis