Cloning and functional expression of the first plant fatty acid elongase specific for Delta(6)-polyunsaturated fatty acids.
In order to elucidate the biosynthesis of long-chain polyunsaturated fatty acids (PUFAs) in plants we searched for a cDNA encoding a Delta(6)-specific PUFA elongase from Physcomitrella patens, which is known to contain high proportions of arachidonic acid (20:4 Delta(5,8,11,14)). An EST clone from P. patens was identified by its low homology to the yeast gene ELO1, which is required for the elongation of medium-chain fatty acids. We functionally characterized this cDNA by heterologous expression in Saccharomyces cerevisiae grown in the presence of several fatty acids. Analysis of the fatty acid profile of the transgenic yeast revealed that the cDNA encodes a protein that leads to the elongation of the C(18) Delta(6)-polyunsaturated fatty acids gamma-linolenic acid (18:3 Delta(6,9,12)) and stearidonic acid (18:4 Delta(6,9,12,15)), which were recovered to 45-51% as their elongation products. In contrast, linoleic and alpha-linolenic acids were hardly elongated and we could not measure any elongation of saturated and mono-unsaturated fatty acids (including 18:1 Delta(6)), indicating that the elongase is highly specific for the polyunsaturated nature of the fatty acid acting as substrate.
Zank
T K
TK
Institut für Allgemeine Botanik, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany.
Zähringer
U
U
Lerchl
J
J
Heinz
E
E
D000123:Acetyltransferases / Q000235:genetics* / Q000378:metabolism*; D019068:Bryopsida / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D000081031:Fatty Acid Elongases; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013379:Substrate Specificity
D005231:Fatty Acids, Unsaturated; D011994:Recombinant Proteins; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases