Production of a Brassica napus Low-Molecular Mass Acyl-Coenzyme A-Binding Protein in Arabidopsis Alters the Acyl-Coenzyme A Pool and Acyl Composition of Oil in Seeds      

Abstract

Low-molecular mass (10 kD) cytosolic acyl-coenzyme A-binding protein (ACBP) has a substantial influence over fatty acid (FA) composition in oilseeds, possibly via an effect on the partitioning of acyl groups between elongation and desaturation pathways. Previously, we demonstrated that the expression of a Brassica napus ACBP (BnACBP) complementary DNA in the developing seeds of Arabidopsis (Arabidopsis thaliana) resulted in increased levels of polyunsaturated FAs at the expense of eicosenoic acid (20:1 cisD11 ) and saturated FAs in seed oil. In this study, we investigated whether alterations in the FA composition of seed oil at maturity were correlated with changes in the acyl-coenzyme A (CoA) pool in developing seeds of transgenic Arabidopsis expressing BnACBP. Our results indicated that both the acyl-CoA pool and seed oil of transgenic Arabidopsis lines expressing cytosolic BnACBP exhibited relative increases in linoleic acid (18:2 cisD9,12 ; 17.9%-44.4% and 7%-13.2%, respectively) and decreases in 20:1 cisD11 (38.7%-60.7% and 13.8%-16.3%, respectively). However, alterations in the FA composition of the acylCoA pool did not always correlate with those seen in the seed oil. In addition, we found that targeting of BnACBP to the endoplasmic reticulum resulted in FA compositional changes that were similar to those seen in lines expressing cytosolic BnACBP, with the most prominent exception being a relative reduction in a-linolenic acid (18:3 cisD9,12,15 ) in both the acyl-CoA pool and seed oil of the former (48.4%-48.9% and 5.3%-10.4%, respectively). Overall, these data support the role of ACBP in acyl trafficking in developing seeds and validate its use as a biotechnological tool for modifying the FA composition of seed oil.

Plant acyl-CoA-binding proteins: An emerging family involved in plant development and stress responses

“…On acyl-CoA profiling, the acbp6 knockout mutant demonstrated an accumulation of unsaturated C18-CoAs in developing seeds and seedlings[32] consistent with previous observations on transgenic Arabidopsis seeds overexpressing the 10-kDa B.napus ACBP[86]. The variation in acyl-CoA composition of the double/triple mutants may ultimately affect seed development and germination.…”

“…However, some recent studies have shown that plant ACBPs are also involved in the biosynthesis of neutral lipids such as TAG in Arabidopsis seeds [32,68,82,86]. In mammals, ACBPs have been shown to affect TAG accumulation [39,144,194].…”

“…napus ACBP affected fatty acid composition in Arabidopsis seeds [82,86], wherein ~ 60% of the total dry weight are lipid (mainly TAGs) derived [1]. In Arabidopsis ACBPs, a double mutation in AtACBP1 and AtACBP2, the two ER…”

“…Changes in plant morphology of the transgenic lines included increases in inflorescence diameter and thickness of rosette leaves which displayed an accumulation of anthocyanin on their abaxial surface [89]. In Arabidopsis, the overexpression of the Class I B. napus ACBP in seeds affected fatty acid composition with increases in 18:2 and decreases in 20:1, during seed development and maturation[82,86]. As Arabidopsis ACBPs are currently the best-characterized in the Plant…”

Properties and Biotechnological Applications of Acyl‐CoA:diacylglycerol Acyltransferase and Phospholipid:diacylglycerol Acyltransferase from Terrestrial Plants and Microalgae

“…4). The activity of microsomal DGAT activity has been shown to be activated by proteins such as acyl-CoA-binding protein, bovine serum albumin, and human acylation-stimulating protein (Hobbs and Hills, 2000;Little et al, 1994;Weselake et al, 2000;Yurchenko et al, 2014), although specific plant regulatory proteins modulating DGAT1 has yet to be identified. Furthermore, microsomal DGAT activity in Arabidopsis was inhibited by niacin (Hobbs and Hills, 2000); this compound was later shown to noncompetitively inhibit mouse DGAT2 (Ganji et al, 2004).…”