Abstract
Sulfoquinovosyl diacylglycerol (SQDG) is the sole lipid with a sulfur atom in chloroplasts and cyanobacteria. Roles of SQDG have been defined in the photosynthetic apparatus (Sato 2004). We here examined the physiological significance of SQDG in a green alga Chlamydomonas reinhardtii after the shift of the cells to sulfur-free condition. The sulfur-starvation brought about conversion of SQDG that had occupied 12% of the sulfur-atom in the cells into the other cellular compounds. However, the synthetic activity of SQDG remained unaltered with an increase in the transcript level of the gene for UDP-sulfoquinovose synthase, one of the genes for SQDG synthesis. These results implied that, under sulfur-starved condition, preexisting SQDG serves as the sulfur-source, and that de novo synthesized SQDG plays some crucial role.
N. Sato (2004) Roles of the acidic lipids sulfoquinovosyl diacylglycerol and phosphatidylglycerol in photosynthesis: their specificity and evolution. J. Plant Res. (vol.6)
