title: Studies on reconstituted partially purified glycerophosphate acyltransferase from Escherichia coli.
abstract: Solubilized glycerophosphate acyltransferase from Escherichia coli was reconstituted in small unilamellar vesicles consisting of phosphatidylcholine/phosphatidylglycerol in a molar ratio of 4:1. Glycerol 3-phosphate, trapped inside these vesicles, cannot be acylated by the enzyme upon addition of extra-vesicular palmitoyl-CoA. Thus, substrate-binding sites and active sites are asymmetrically oriented in the model membrane. When up to 10 mol/100 mol lysophosphatidic acid was incorporated in the vesicles a decrease in glycerophosphate acyltransferase activity is observed at amounts exceeding 1 mol% lysophosphatidate. Similar experiments, using lysophosphatidylcholine and phosphatidic acid, suggest the decrease to result from an increase in negative surface charge. Reconstituted glycerophosphate acyltransferase exhibits a preference for palmitoyl-CoA over oleoyl-CoA. This preference increases considerably at elevated temperatures. The glycerophosphate acyltransferase could, therefore, participate in the temperature-dependent changes in the fatty acid composition of the phospholipids in E. coli.
mesh_terms: D000217:Acyltransferases / Q000302:isolation & purification*; D055598:Chemical Phenomena; D002621:Chemistry; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000201:enzymology*; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000302:isolation & purification* / Q000378:metabolism; D008567:Membranes, Artificial; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D008567:Membranes, Artificial; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D000217:Acyltransferases; D005992:Glycerol-3-Phosphate O-Acyltransferase