Diacylglycerol-phosphatidylethanolamine exchange in Escherichia coli.
The conversion of [3H]- or [14C]diacylglycerol to labelled phosphatidylethanolamine by dialysed, particulate fraction of Escherichia coli was studied. The reaction occurred in the presence of hydroxylamine, under which conditions, the synthesis of [14C]phosphatidylethanolamine from CDP-diacylglycerol and [14C]serine did not occur. The conversion was enhanced by addition of dilauroyl- or dioleoylphosphatidylethanolamine. A conversion of [3H]- or [14C]phosphatidylethanolamine to labelled diacylglycerol could also be readily demonstrated provided unlabelled diacylglycerol was added. Double-labelled [acyl-3H, 32P]phosphatidylethanolamine was converted to labelled diacylglycerol without formation of labelled water-soluble products. The formation of double-labelled phosphatidylethanolamine from [3H]diacyl[14C]glycerol or of double-labelled diacylglycerol from [acyl-3H,glycerol-14C]phosphatidylethanolamine occurred without significant change in isotope ratio. When [acyl-3H]phosphatidylethanolamine was incubated with increasing concentrations of [acyl-14C]diacylglycerol, correspondingly increasing concentrations of [14C]phosphatidylethanolamine were formed which matched the concentrations of [3H]diacylglycerol produced concurrently. It was concluded that E. coli extracts can catalyze an exchange between the diacylglycerol moiety of phosphatidylethanolamine and free diacylglycerol with complete sparing of the phosphoethanolamine moiety.
Proulx
P
P
Department of Biochemistry, Faculty of Health Sciences, University of Ottawa, Ontario, Canada.
Aubry
H
H
D004075:Diglycerides / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D005989:Glycerides / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism*
D004075:Diglycerides; D005989:Glycerides; D010714:Phosphatidylethanolamines