PHOSPHATIDYLGLYCEROL ACETAL OF PLASMENYLETHANOLAMINE AS AN INTERMEDIATE IN ETHER LIPID FORMATION IN CLOSTRIDIUM-BUTYRICUM

The formation and turnover of the recently discovered phosphatidylglycerol acetal of plasmenylethanolamine was investigated in Clostridium butyricum. Incorporation of phosphate into the phospholipids was studied by using [32P]orthophosphate in pulse and pulse-chase experiments in growing cells. Among the ethanolamine-containing lipids, the diacyl form of phosphatidylethanolamine was labeled most rapidly, followed by the phosphatidylglycerol acetal of plasmenylethanolamine and plasmenylethanolamine. The glycerol acetal of plasmenylethanolamine was labeled most slowly. There was rapid turnover of approximately one half of the newly labeled phosphatidylethanolamine pool. Since the kinetics of labeling of the small pool of phosphatidylglycerol acetal of plasmenylethanolamine and the larger pool of plasmenylethanolamine were similar during the early time courses of pulse and pulse-chase experiments, the results argue against the derivation of phosphatidylglycerol acetal of plasmenylethanolamine from plasmenylethanolamine. The results are consistent with the derivation of glycerol acetal of plasmenylethanolamine from either phosphatidylglycerol acetal of plasmenylethanolamine or plasmenylethanolamine.