Phospholipid dependence of homogeneous, reconstituted sn-glycerol-3-phosphate acyltransferase of Escherichia coli.
A novel mixed micelle assay for the sn-glycerol-3-phosphate acyltransferase of Escherichia coli was developed using the nonionic detergent octaethylenegly-coldodecyl ether. The assay permitted investigation of the phospholipid dependence of enzyme activity at phospholipid/detergent ratios of 5:1 (w/w) to 2:1 depending on the phospholipid employed. The higher ratio yielded maximal activity when E. coli phospholipids were used; the lower ratio was observed with cardiolipin(E. coli). Phosphatidylglycerol(E. coli) and phosphatidylethanolamine(E. coli) also restored enzyme activity. Activation by phosphatidylethanolamine(E. coli) was pH-dependent and relatively inefficient. The synthetic, disaturated (1,2-palmitoyl)phosphatidylglycerol reconstituted only 25% of the total enzyme activity as that observed with the monounsaturated (1-palmitoyl, 2-oleoyl) species. Full activation of enzyme was achieved with (1,2-dioleoyl)phosphatidylglycerol. Phosphatidylcholine and phosphatidic acid were unable to reconstitute enzyme activity. Chromatographic sizing of the sn-glycerol-3-phosphate acyltransferase, following reconstitution in cardiolipin(E. coli)/octaethyleneglycoldodecyl ether mixed micelles, suggested that the monomeric form of the enzyme was active.
Scheideler
M A
MA
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
Bell
R M
RM
D000217:Acyltransferases / Q000378:metabolism*; D002850:Chromatography, Gel; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008823:Micelles; D008970:Molecular Weight; D010743:Phospholipids / Q000494:pharmacology / Q000502:physiology*
D008823:Micelles; D010743:Phospholipids; D000217:Acyltransferases; D005992:Glycerol-3-Phosphate O-Acyltransferase