Properties of lysophosphatidylcholine acyltransferase from Brassica napus cultures.
Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT; EC 2.3.1.23) catalyzes the acyl-CoA-dependent acylation of lysophosphatidylcholine (LPC) to produce PC and CoA. LPCAT activity may affect the incorporation of fatty acyl moieties at the sn-2 position of PC where PUFA are formed and may indirectly influence seed TAG composition. LPCAT activity in microsomes prepared from microspore-derived cell suspension cultures of oilseed rape (Brassica napus L. cv Jet Neuf) was assayed using [1-14C]acyl-CoA as the fatty acyl donor. LPCAT activity was optimal at neutral pH and 35 degrees C, and was inhibited by 50% at a BSA concentration of 3 mg mL(-1). At acyl-CoA concentrations above 20 microM, LPCAT activity was more specific for oleoyl (18:1)-CoA than stearoyl (18:0)- and palmitoyl (16:0)-CoA. Lauroyl (12:0)-CoA, however, was not an effective acyl donor. LPC species containing 12:0, 16:0, 18:0, or 18:1 as the fatty acyl moiety all served as effective acyl acceptors for LPCAT, although 12:0-LPC was somewhat less effective as a substrate at lower concentrations. The failure of LPCAT to catalyze the incorporation of a 12:0 moiety from acyl-CoA into PC is consistent with the tendency of acyltransferases to discriminate against incorporation of this fatty acyl moiety at the sn-2 position of TAG from the seed oil of transgenic B. napus expressing a medium-chain thioesterase.
Furukawa-Stoffer
Tara L
TL
Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4 Canada.
Boyle
Riley M
RM
Thomson
Amber L
AL
Sarna
Magdalena A
MA
Weselake
Randall J
RJ
D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000378:metabolism*; D000214:Acyl Coenzyme A / Q000378:metabolism; D029688:Brassica napus / Q000201:enzymology*; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008244:Lysophosphatidylcholines / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors
D000214:Acyl Coenzyme A; D002250:Carbon Radioisotopes; D005231:Fatty Acids, Unsaturated; D008244:Lysophosphatidylcholines; D008243:1-Acylglycerophosphocholine O-Acyltransferase