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Structurally divergent lysophosphatidic acid acyltransferases with high selectivity for saturated medium chain fatty acids from Cuphea seeds
Author(s) -
Kim Hae Jin,
Silva Jillian E.,
Iskandarov Umidjon,
Andersson Mariette,
Cahoon Rebecca E.,
Mockaitis Keithanne,
Cahoon Edgar B.
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13063
Subject(s) - acyltransferases , camelina sativa , lysophosphatidic acid , biochemistry , camelina , acyltransferase , fatty acid , biology , complementary dna , degree of unsaturation , phosphatidic acid , biosynthesis , enzyme , chemistry , gene , food science , chromatography , ecology , receptor , crop , phospholipid , membrane
Summary 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 ( TAG s). In the case of TAG s, this reaction is typically catalyzed by an LPAT 2 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 LPAT s with variant substrate specificities, deep transcriptomic mining was performed on seeds of two Cuphea species producing TAG s that are highly enriched in saturated C8 and C10 fatty acids. From these analyses, cDNA s for seven previously unreported LPAT s were identified, including cDNA s from Cuphea viscosissima ( Cv LPAT 2 ) and Cuphea avigera var. pulcherrima ( Cpu LPAT 2a ) encoding microsomal, seed‐specific class A LPAT 2s and a cDNA from C. avigera var. pulcherrima ( Cpu LPATB ) 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 cDNA s for various Cuphea FatB acyl–acyl carrier protein thioesterases (FatB) that produce a variety of saturated medium‐chain fatty acids. Cv LPAT 2 and Cpu LPAT 2a 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 LPAT s. Cpu LPATB expression generated TAG s with 14:0 at the sn ‐2 position, but not 10:0. Identification of these LPAT s provides tools for understanding the structural basis of LPAT substrate specificity and for generating altered oil functionalities.