title: Donor-side photoinhibition in photosystem II from Chlamydomonas reinhardtii upon mutation of tyrosine-Z in the D1 polypeptide to phenylalanine.
abstract: When tyrosine-Z of the D1-polypeptide of the photosystem II from Chlamydomonas reinhardtii was changed to phenylalanine, the rapid donor to P680+ was lost, and P680+ accumulated on illumination. The rapid donation from tyrosine-Z was replaced by a slow electron transfer from an endogenous donor. Spectrophotometric measurements showed that carotenoids and chlorophylls were bleached by the P680+ either directly or indirectly upon illumination. The carotenoid bleaching was inhibited in the presence of SOD or catalase, but the reaction did not require molecular oxygen as an electron acceptor. These observations led us to conclude that active oxygen radicals, possibly hydroxyl radicals, take part in the destruction of carotenoids in the Y161F mutant. Possible mechanisms for the destruction are discussed.
authors.affiliation: Center for Biophysics and Computational Biology, University of Illinois, Urbana, 61801, USA.
authors.forename: J
authors.initials: J
authors.lastname: Minagawa
authors.forename: D M
authors.initials: DM
authors.lastname: Kramer
authors.forename: A
authors.initials: A
authors.lastname: Kanazawa
authors.forename: A R
authors.initials: AR
authors.lastname: Crofts
mesh_terms: D020418:Algal Proteins; D000818:Animals; D001483:Base Sequence; D002268:Carboxypeptidases; D002338:Carotenoids / Q000378:metabolism; D002374:Catalase / Q000378:metabolism / Q000494:pharmacology; D016825:Chlamydomonas reinhardtii / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism; D005292:Ferricyanides / Q000378:metabolism / Q000494:pharmacology; D005453:Fluorescence; D005609:Free Radicals; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000235:genetics; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D043484:Proprotein Convertases; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism / Q000494:pharmacology; D014443:Tyrosine / Q000235:genetics
chemical_list: D020418:Algal Proteins; D005292:Ferricyanides; D005609:Free Radicals; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; C007931:hexacyanoferrate III; D002734:Chlorophyll; D002338:Carotenoids; D014443:Tyrosine; D010649:Phenylalanine; D002374:Catalase; D013482:Superoxide Dismutase; D002268:Carboxypeptidases; D010450:Endopeptidases; D043484:Proprotein Convertases; C073491:photosystem II, D1 polypeptide carboxy-terminal processing protease