Role of sulfoquinovosyl diacylglycerol for the maintenance of photosystem II in Chlamydomonas reinhardtii.
The physiological role of sulfoquinovosyl diacylglycerol (SQDG) in photosynthesis was investigated with a SQDG defective mutant (hf-2) of Chlamydomonas reinhardtii that did not have any detectable amount of SQDG. The mutant showed a lower rate of photosystem II (PSII) activity by approximately 40% and also a lower growth rate than those of the wild-type. Results of genetical analysis of hf-2 strongly suggest that the SQDG defect and the lowered PSII activity are due to a single gene mutation. The supplementation of SQDG to hf-2 cells restored the lowered PSII activity to the same level as that of wild-type cells, and also enabled the mutant to grow even in the presence of 135 nm 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Moreover, the incubation of isolated thylakoid membranes of hf-2 with SQDG raised the lowered PSII activity. Chemical modifications of SQDG impaired the recovery of PSII activity. The results suggest that SQDG is indispensable for PSII activity in Chlamydomonas by maintaining PSII complexes in their proper state.
Minoda
Ayumi
A
School of Life Science, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Japan.
Sato
Norihiro
N
Nozaki
Hisayoshi
H
Okada
Katsuhiko
K
Takahashi
Haruko
H
Sonoike
Kintake
K
Tsuzuki
Mikio
M
D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D006017:Glycolipids / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045332:Photosystem II Protein Complex
D006017:Glycolipids; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; C013694:sulfoquinovosyl diglyceride