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Decrease in the efficiency of the electron donation to tyrosine Z of photosystem II in an SQDG‐deficient mutant of Chlamydomonas
Author(s) -
Minoda Ayumi,
Sonoike Kintake,
Okada Katsuhiko,
Sato Norihiro,
Tsuzuki Mikio
Publication year - 2003
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/s0014-5793(03)00981-5
Subject(s) - thylakoid , chlamydomonas , mutant , photosystem ii , dcmu , electron transport chain , chemistry , tyrosine , biophysics , biology , biochemistry , photosynthesis , chloroplast , gene
Photosystem (PS) II activity of a sulfoquinovosyl diacylglycerol (SQDG)‐deficient mutant ( hf ‐2) of Chlamydomonas was partially decreased compared with that of wild‐type. The susceptibility to 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) was also modified in the mutant. Photometric measurements in the isolated thylakoid membranes of hf ‐2 revealed that the lowered activity in the mutant was derived from a decrease in the efficiency of the electron donation from water to tyrosine Z, not from the efficiency of the electron transport from Q A to Q B . This result was confirmed by the decay kinetics of chlorophyll fluorescence determined in vivo. We conclude that SQDG contributes to maintaining the conformation of PSII complexes, particularly that of D1 polypeptides, which are necessary for maximum activities in Chlamydomonas .