Abstract
An anionic glycerolipid, sulfoquinovosyldiacylglycerol (SQDG), is present in the thylakoid membranes of photosynthetic organisms. We previously produced a mutant defective in SQDG synthesis from a cyanobacterium, Synechocystis PCC6803, for the study of the role of SQDG in photosynthesis, demonstrating that SQDG is essential for growth of PCC6803 and has an important role in photosynthesis. In this study, we found that SQDG plays an important function for the maintenance of normal properties of photosystem II (PSII). In contrast, the SQDG-null mutant of Synechococcus PCC7942 we produced could grow without SQDG-supplementation as was reported previously for another SQDG-null mutant of PCC7942 (Güler et al., 1996, J.Biol.Chem. 271, 7501) and showed the normal properties of PSII. Therefore, the difference exists for SQDG requirement of PSII and growth in cyanobacteria. It would provide us with a clue for elucidation of the molecular interaction of SQDG with the PSII complex.
