Abstract

Lysophosphatidic acid acyltransferase (LPAT) catalyzes acylation of the sn-2 position on lysophosphatidic acid by an acyl CoA substrate to produce the phosphatidic acid precursor of polar glycerolipids and triacylglycerols (TAGs). In the case of TAGs, this reaction is typically catalyzed by an LPAT2 from microsomal LPAT class A that has high specificity for C18 fatty acids containing Delta 9 unsaturation. Because of this specificity, the occurrence of saturated fatty acids in the TAG sn-2 position is infrequent in seed oils. To identify LPATs with variant substrate specificities, deep transcriptomic mining was performed on seeds of two Cuphea species producing TAGs that are highly enriched in saturated C8 and C10 fatty acids. From these analyses, cDNAs for seven previously unreported LPATs were identified, including cDNAs from Cuphea viscosissima (CvLPAT2) and Cuphea avigera var. pulcherrima (CpuLPAT2a) encoding microsomal, seed-specific class A LPAT2s and a cDNA from C. avigera var. pulcherrima (CpuLPATB) encoding a microsomal, seed-specific LPAT from the bacterial-type class B. The activities of these enzymes were characterized in Camelina sativa by seed-specific co-expression with cDNAs for various Cuphea FatB acyl-acyl carrier protein thioesterases (FatB) that produce a variety of saturated medium-chain fatty acids. CvLPAT2 and CpuLPAT2a expression resulted in accumulation of 10: 0 fatty acids in the Camelina sativa TAG sn-2 position, indicating a 10: 0 CoA specificity that has not been previously described for plant LPATs. CpuLPATB expression generated TAGs with 14: 0 at the sn-2 position, but not 10:0. Identification of these LPATs provides tools for understanding the structural basis of LPAT substrate specificity and for generating altered oil functionalities.

Keywords

lysophosphatidic acid acyltransferase; triacylglycerol; fatty acid; acyl CoA; oilseed; medium chain fatty acid; Cuphea; Cuphea viscosissima; Cuphea avigera var. pulcherrima; Camelina sativa

Published in

Plant Journal
2015, Volume: 84, number: 5, pages: 1021-1033
Publisher: Wiley-Blackwell

SLU Authors

• Andersson, Mariette

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Plant Biotechnology


Publication identifier

DOI: https://doi.org/10.1111/tpj.13063

Permanent link to this page (URI)

https://res.slu.se/id/publ/72396