cDNA Clones from Limnanthes Douglasii Encoding an Erucoyl-CoA Specific 1-Acylglycerol-3-Phosphate Acyltransferase

Abstract

Rapeseed oil represents a renewable resource suitable for different technical purposes. Its industrial applicability can be improved by a homogenous fatty acid composition consisting of 90 % of one technically attractive fatty acid, such as erucic acid [1]. The content of erucic acid in the oil of current rapeseed varieties is limited to about 60 % since erucic acid is esterified in the sn-1 and sn-3 position of the glycerol backbone only, whereas the sn-2 position carries unsaturated C₁₈ acyl groups [2]. This fatty acid pattern of rapeseed oil is established by the microsomal acyltransferases involved in triacylglycerol biosynthesis [3]. Due to the pronounced specificity and selectivity of the l-acylglycerol-3-phosphate acyltransferase for unsaturated C₁₈ acyl groups, erucic acid is excluded from the sn-2 position of the glycerol backbone and, thus, the formation of trierucin is prevented [3, 4]. In contrast to the acyltransferase of rapeseed, the respective seed-specific enzyme from Limnanthes douglasii effectively utilizes erucoyl-CoA as substrate [5]. To achieve trierucin biosynthesis in rapeseed by genetic engineering, we have isolated cDNAs from Limnanthes douglasii encoding an erucoyl-CoA specific 1-acylglycerol-3-phosphate acyltransferase.