title: The ability of cyanobacterial cells to restore UV-B radiation induced damage to Photosystem II is influenced by photolyase dependent DNA repair.
abstract: Damage of DNA and Photosystem-II are among the most significant effects of UV-B irradiation in photosynthetic organisms. Both damaged DNA and Photosystem-II can be repaired, which represent important defense mechanisms against detrimental UV-B effects. Correlation of Photosystem-II damage and repair with the concurrent DNA damage and repair was investigated in the cyanobacterium Synechocystis PCC6803 using its wild type and a photolyase deficient mutant, which is unable to repair UV-B induced DNA damages. A significant amount of damaged DNA accumulated during UV-B exposure in the photolyase mutant concomitant with decreased Photosystem-II activity and D1 protein amount. The transcript level of psbA3, which is a UV-responsive copy of the psbA gene family encoding the D1 subunit of the Photosystem-II reaction center, is also decreased in the photolyase mutant. The wild-type cells, however, did not accumulate damaged DNA during UV-B exposure, suffered smaller losses of Photosystem-II activity and D1 protein, and maintained higher level of psbA3 transcripts than the photolyase mutant. It is concluded that the repair capacity of Photosystem-II depends on the ability of cells to repair UV-B-damaged DNA through maintaining the transcription of genes, which are essential for protein synthesis-dependent repair of the Photosystem-II reaction center.
authors.affiliation: Biological Research Center of the Hungarian Academy of Sciences, Institute of Plant Biology, Szeged, Hungary.
authors.forename: István-Zoltán
authors.initials: IZ
authors.lastname: Vass
authors.forename: Péter B
authors.initials: PB
authors.lastname: Kós
authors.forename: László
authors.initials: L
authors.lastname: Sass
authors.forename: Csaba I
authors.initials: CI
authors.lastname: Nagy
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D004249:DNA Damage; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000172:deficiency / Q000235:genetics*; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis / Q000528:radiation effects; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D014158:Transcription, Genetic / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D045332:Photosystem II Protein Complex; D020033:Protein Isoforms; C422369:photosystem II, psbA subunit; C085993:psbDI protein, cyanobacteria; D004255:Deoxyribodipyrimidine Photo-Lyase