title: D1 protein turnover is involved in protection of Photosystem II against UV-B induced damage in the cyanobacterium Arthrospira (Spirulina) platensis.
abstract: By using two strains of Arthrospira (Spirulina)platensis, an economically important filamentous cyanobacterium, we compared the impairment of PSII activity and loss of D1 protein content under UV-B radiation. Our study showed that UV-B radiation induced a gradual loss of the oxygen-evolving activity to about 56% after 180 min UV-B irradiation both in strains 439 and D-0083, which have been kept under indoor and an outdoor culturing conditions, respectively for a prolonged period of time. The loss of oxygen evolution was accelerated in both strains in the presence of lincomycin, an inhibitor of protein synthesis, and the amount of D1 protein showed a decrease comparable to that of oxygen evolution during the UV-B exposure. However, the UV-B induced loss of oxygen-evolving activity and D1 protein amount was largely prevented when A. platensis cells were exposed to UV-B irradiance supplemented with visible light. Comparison of the two strains also showed a smaller extent of D1 protein synthesis dependent PSII repair in the indoor strain. Our results show that turnover of the D1 protein is an important defense mechanism to counteract the UV-B induced damage of PSII in A. platensis, and also that visible light plays an important role in maintaining the function of PSII under simultaneous exposure to UV-B and visible light.
authors.affiliation: Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Wu
authors.forename: Leyla
authors.initials: L
authors.lastname: Abasova
authors.forename: Otilia
authors.initials: O
authors.lastname: Cheregi
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Deák
authors.forename: Kunshan
authors.initials: K
authors.lastname: Gao
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
mesh_terms: D010100:Oxygen / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D053545:Spirulina / Q000201:enzymology / Q000528:radiation effects*; D020524:Thylakoids / Q000378:metabolism / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D045332:Photosystem II Protein Complex; C422369:photosystem II, psbA subunit; D010100:Oxygen