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Donor‐side photoinhibition in photosystem II from Chlamydomonas reinhardtii upon mutation of tyrosine‐Z in the D1 polypeptide to phenylalanine
Author(s) -
Minagawaa Jun,
Kramer David M.,
Kanazawa Atsuko,
Crofts Antony R.
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00581-9
Subject(s) - chlamydomonas reinhardtii , photosystem ii , p680 , photoinhibition , photochemistry , chemistry , tyrosine , radical , phenylalanine , catalase , chlamydomonas , electron transfer , biochemistry , photosynthesis , mutant , photosystem i , enzyme , amino acid , gene
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 P 680 + 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.