title: Ultraviolet-B photodestruction of a light-harvesting complex.
abstract: Cyanobacteria are important contributors to global photosynthesis in both marine and terrestrial environments. Quantitative data are presented on UV-B-induced damage to the major cyanobacterial photosynthetic light harvesting complex, the phycobilisome, and to each of its constituent phycobiliproteins. The photodestruction quantum yield, phi295 nm, for the phycobiliproteins is high (approximately 10(-3), as compared with approximately 10(-7) for visible light). Energy transfer on a picosecond time scale does not compete with photodestruction. Photodamage to phycobilisomes in vitro and in living cells is amplified by causing dissociation and loss of function of the complex. In photosynthetic organisms, UV-B damage to light-harvesting complexes may significantly exceed that to DNA.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, 94720-3206, USA.
authors.forename: K
authors.initials: K
authors.lastname: Lao
authors.forename: A N
authors.initials: AN
authors.lastname: Glazer
mesh_terms: D017033:Anabaena / Q000378:metabolism / Q000528:radiation effects*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D008961:Models, Structural; D010782:Photolysis; D045524:Phycobilisomes; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D011789:Quantum Theory; D013053:Spectrophotometry; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; D010940:Plant Proteins