Structurally divergent lysophosphatidic acid acyltransferases with high selectivity for saturated medium chain fatty acids from Cuphea seeds.
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 Δ9 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.
Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
Hae Jin
HJ
Kim
Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
Jillian E
JE
Silva
Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
Umidjon
U
Iskandarov
Department of Plant Breeding Swedish, University of Agricultural Sciences, Alnarp, Sweden.
Mariette
M
Andersson
Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
Rebecca E
RE
Cahoon
Pervasive Technology Institute and Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
Keithanne
K
Mockaitis
Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
Edgar B
EB
Cahoon
D000217:Acyltransferases / Q000737:chemistry* / Q000378:metabolism; D031562:Cuphea / Q000201:enzymology* / Q000378:metabolism; D057225:Data Mining; D005227:Fatty Acids / Q000378:metabolism*; D010802:Phylogeny; D000072417:Protein Domains; D012639:Seeds / Q000201:enzymology / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017423:Sequence Analysis, RNA; D013379:Substrate Specificity; D059467:Transcriptome
D005227:Fatty Acids; D000217:Acyltransferases; C018764:2-acylglycerophosphate acyltransferase
Camelina sativa; Cuphea; Cuphea avigera var. pulcherrima; Cuphea viscosissima; acyl CoA; fatty acid; lysophosphatidic acid acyltransferase; medium chain fatty acid; oilseed; triacylglycerol