A Plant Acyltransferase Involved in Triacylglycerol Biosynthesis Complements an Escherichia Coli sn‐1‐acylglycerol‐3‐phosphate Acyltransferase Mutant

Abstract

The second acylation reaction in glycerolipid biosynthesis is catalyzed by an sn-1 -acylglycerol-3-phosphate acyltransferase. The enzyme of Lirnnunfhes douglusii involved in triacylglycerol synthesis has an unusual specificity for very long chain acyl groups in both of its substrates, namely acyl-CoA and S I I -1 -acylglycerol-3-phosphate, and causes the enrichment of erucoyl groups in the sn-2 position of the seed oil of this plant species. We have isolated a cDNA clone encoding this embryo-specific, microsomal acyltransferase via heterologous complementation of an Escherichia coli mutant deficient in sn-1 -acylglycerol-3-phosphate acyltransferase activity. The open reading frame of the cDNA insert encodes a protein with a length of 281 amino acids, with three predicted membrane-spanning domains and of about 31.7 kDa. The sequence exhibits substantial sequence similaritiy to the sn-1 -acylglycerol-3-phosphate acyltransferase of E. coli. The corresponding transcript was detectable in developing embryos but not in leaves of L. douglasii, and expression of the open reading frame in E. coli caused sn-l-acylglycerol-3-phosphate acyltransferase activity which showed properties different from those of the bacterial acyltransferase but typical of the L. douglusii enzyme involved in triacylglycerol biosynthesis.

Ubiquitous and Endoplasmic Reticulum–Located Lysophosphatidyl Acyltransferase, LPAT2, Is Essential for Female but Not Male Gametophyte Development in Arabidopsis

“…Species in which the seed oils have uncommon acyl moieties at the sn-2 position possess additional seed-specific LPATs that are reactive toward the respective uncommon acyl-CoAs (Cao et al, 1990;Laurant and Huang, 1992;Brown et al, 1995;Frentzen, 1998). Genes encoding cytoplasmic LPATs in maturing seeds or other organs from several species, including maize (Zea mays) (Brown et al, 1994), coconut (Cocos nucifera) (Knutzon et al, 1995), and meadowfoam (Limnanthes alba) (Hanke et al, 1995) have been reported. The deduced amino acid sequences of the enzymes contain transmembrane segments indicative of association with membranes, and the enzyme from the leaf or seed extracts can be recovered in the microsomal fraction.…”

Inheritance and variation of erucic acid content in a transgenic rapeseed (Brassica napus L.) doubled haploid population

“…The Ld-LPAAT gene was cloned and expressed under control of a seed specific promoter in rapeseed. However, this achievement was not accompanied by an increase in erucic acid content in the seed oil (Brown et al 1995;Hanke et al 1995;Lassner et al 1995;Brough et al 1996). In a second approach, the fae1 gene has been cloned from Arabidopsis (James et al 1995) and subsequently from rapeseed.…”

Human Lysophosphatidic Acid Acyltransferase

“…In plants, storage triacylglycerols are synthesized via a four-step pathway that involves acylation of glycerol 3-phosphate at the sn-1 position to form LPA, acylation of LPA by LPAAT, and then conversion of the PA to diacylglycerol by PA phosphatase followed by sn-3 acylation to form triacylglycerol (21). Interest in this metabolic pathway from the perspective of understanding and manipulating plant oil production has resulted in the cloning of several plant cDNAs that encode enzymes with LPAAT activity (22)(23)(24)(25). Interestingly, these cDNAs have extensive * The costs of publication of this article were defrayed in part by the payment of page charges.…”