title: UVB-induced photodamage to phycobilisomes of Synechococcus sp. PCC 7942.
abstract: The effect of UVB irradiation on the phycobilisomes (PBSs) of Synechococcus sp. PCC 7942 cells was studied. The sucrose density-gradient-isolated PBSs from in vivo UVB-treated (280-320 nm) cells showed a strong decrease in beta-phycocyanin (beta PC) and alpha-phycocyanin (alpha PC) polypeptides, in addition to a decrease in the linker polypeptides LCM 75 (linker connecting the core to the thylakoid membranes), LR 33 (linker in the rod structure), LRC 31.5 (linker connecting the rod to the core) and LRC 29. In vitro UVB treatment of gradient-isolated intact PBSs for 1 h had no effect on any of the constituent polypeptides, and only after 2 h was a degradation of LCM 75 and LR 33 and a decrease in beta PC evident. Further investigation of phycobiliproteins (4 h of UVB irradiation) using polyclonal antibody directed against purified whole PBSs revealed that, in vivo, there was a gradual decline in the levels of LCM 75, LR 33, LRC 31.5, LRC 29, beta PC and alpha PC.
authors.affiliation: Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: R
authors.initials: R
authors.lastname: Pandey
authors.forename: S
authors.initials: S
authors.lastname: Chauhan
authors.forename: G S
authors.initials: GS
authors.lastname: Singhal
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism / Q000528:radiation effects*; D000458:Cyanobacteria / Q000378:metabolism / Q000528:radiation effects*; D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; D010798:Phycocyanin / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism / Q000528:radiation effects*; D011817:Rabbits; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; D010940:Plant Proteins; D010798:Phycocyanin