Phospholipid Synthesis by Rhodopseudomonas spheroides in Relation to the Formation of Photosynthetic Pigments

Publisher Website
Google Scholar
Abstract
The concentration of phospholipids in pigmented R. spheroides was higher than that in organisms lacking the photosynthetic pigments; the amounts of lipid phosphorus/mg protein were, respectively, 157 and 90 mumoles. Phosphatidylethanolamine comprised about 40% of the phospholipids, the remainder consisting of phosphatidic-acid, phosphatidylglycerol and phosphatidylcholine. The phospholipids were confined to the membrane fraction of the organisms. As organisms adapted from the non-pig-mented to the pigmented state the amount of lipid phosphorus/mg protein increased. Experiments with radioactive phosphate showed phosphatidyl glycerol to incorporate label more rapidly than the other phospholipids. It is suggested that the formation of the photosynthetic pigments may be accompanied by modifications to the membrane structure so that it can accommodate more phospholipids.