caa a22 4500 477100910 CHVBK 20180405111541.0 cr unu---uuuuu 170330e19960401xx s 000 0 eng 10.1007/BF00262653 doi (NATIONALLICENCE)springer-10.1007/BF00262653 Photoinhibition and repair in Dunaliella salina acclimated to different growth irradiances [Elektronische Daten] [Irene Baroli, Anastasios Melis] The light-dependent rate of photosystem-II (PSII) damage and repair was measured in photoautotrophic cultures of Dunaliella salina Teod. grown at different irradiances in the range 50-3000 μmol photons · m−2· s−1. Rates of cell growth increased in the range of 50-800 μmol photons·m−2·s−1, remained constant at a maximum in the range of 800-1,500 μmol photons·m−2 ·s−1, and declined due to photoinhibition in the range of 1500-3000 μmol photons·m−2·s−1. Western blot analyses, upon addition of lincomycin to the cultures, revealed first-order kinetics for the loss of the PSII reaction-center protein (D1) from the 32-kDa position, occurring as a result of photodamage. The rate constant of this 32-kDa protein loss was a linear function of cell growth irradiance. In the presence of lincomycin, loss of the other PSII reaction-center protein (D2) from the 34-kDa position was also observed, occurring with kinetics similar to those of the 32-kDa form of D1. Increasing rates of photodamage as a function of irradiance were accompanied by an increase in the steady-state level of a higher-molecular-weight protein complex (≈ 160-kDa) that cross-reacted with D1 antibodies. The steady-state level of the 160-kDa complex in thylakoids was also a linear function of cell growth irradiance. These observations suggest that photodamage to D1 converts stoichiometric amounts of D1 and D2 (i.e., the D1/D2 heterodimer) into a ≈160-kDa complex. This complex may help to stabilize the reaction-center proteins until degradation and replacement of D1 can occur. The results indicated an intrinsic half-time of about 60 min for the repair of individual PSII units, supporting the idea that degradation of D1 after photodamage is the rate-limiting step in the PSII repair process. Springer-Verlag, 1996 D1 protein nationallicence Dunaliella nationallicence Green algae nationallicence Photodamage nationallicence Photoinhibition nationallicence Photosystem II nationallicence Chl : chlorophyll nationallicence PSI : photosystem I nationallicence PSII : photosystem II nationallicence D1 : the 32-kDa reaction-center protein of PSII, encoded by the chloroplast psbA gene nationallicence D2 : the 34-kDa reactioncenter protein of PSII, encoded by the chloroplast psbD gene nationallicence QA : primary electron-accepting plastoquinone of PSII nationallicence Baroli Irene Department of Plant Biology, University of California, 411 Koshland Hall, 94720-3102, Berkeley, CA, USA aut Melis Anastasios Department of Plant Biology, University of California, 411 Koshland Hall, 94720-3102, Berkeley, CA, USA aut Planta Springer-Verlag 198/4(1996-04-01), 640-646 0032-0935 198:4<640 1996 198 425 https://doi.org/10.1007/BF00262653 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00262653 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Baroli Irene Department of Plant Biology, University of California, 411 Koshland Hall, 94720-3102, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Melis Anastasios Department of Plant Biology, University of California, 411 Koshland Hall, 94720-3102, Berkeley, CA, USA aut NATIONALLICENCE 773 0- Planta Springer-Verlag 198/4(1996-04-01), 640-646 0032-0935 198:4<640 1996 198 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer