Release and reactive-oxygen-mediated damage of the oxygen-evolving complex subunits of PSII during photoinhibition.
Under photoinhibitory illumination of spinach PSII membranes, the oxygen-evolving complex subunits, OEC33, 24 and 18, were released from PSII. The liberated OEC33 and also OEC24 to a lesser extent were subsequently damaged and then exhibited smeared bands in SDS/urea-PAGE. Once deteriorated, OEC33 could not bind to PSII. The effects of scavengers and chelating reagents on the damage indicated that hydroxyl radicals generated from superoxide in the presence of metal ions were responsible for the damage. These results suggest that, like the D1 protein of the PSII reaction center complex, OEC subunits suffer oxidative damage and turnover under illumination.
Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530 Japan.
Takahiro
T
Henmi
Mitsue
M
Miyao
Yasusi
Y
Yamamoto
D002462:Cell Membrane / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000378:metabolism / Q000528:radiation effects; D008670:Metals / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology* / Q000528:radiation effects; D010100:Oxygen / Q000378:metabolism*; D010775:Photic Stimulation; D045332:Photosystem II Protein Complex / Q000378:metabolism* / Q000528:radiation effects; D021122:Protein Subunits / Q000378:metabolism / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018724:Spinacia oleracea / Q000166:cytology / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
D016166:Free Radical Scavengers; D008670:Metals; D045332:Photosystem II Protein Complex; D021122:Protein Subunits; D017382:Reactive Oxygen Species; C064388:oxygen-evolving complex, 33 kDa protein; D013481:Superoxides; D017665:Hydroxyl Radical; D010100:Oxygen