Submitted to: Biocatalysis and Agricultural Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2015
Publication Date: 1/29/2015
Citation: Mckeon, T.A., He, X. 2015. Castor diacylglycerol acyltransferase type1(DGAT1)displays greater activity with diricinolein than Arabidopsis DGAT1. Biocatalysis and Agricultural Biotechnology. 4:276-278.
Interpretive Summary: Castor oil is an important feedstock that provides many high quality products similar to those obtained from petroleum. It is considered problematic as a crop due to the presence of some noxious proteins in the seed. Attempts to produce a similar oil in other plants have not yet succeeded because the biochemistry of castor oil is not well understood. This work identifies a key enzyme involved in castor oil biosynthesis that could be useful in replicating castor oil production. The ability to produce an oil similar to castor oil in a domestic crop would provide a renewable resource that could be used to replace some products currently derived from petroleum.
Technical Abstract: Castor oil contains the hydroxy fatty acid ricinoleate as a major (90%) component. The diacylglycerol acyltransferase (DGAT) carries out the final reaction step in the biosynthesis of triacylglycerol, the principal constituent of seed oil, and has been considered to be the step that controls the oil content of seeds. In order to better understand how castor is able to produce such an unusual oil, we have compared the substrate selectivity of the type 1 DGATs (DGAT1)) from castor (RcDGAT1) and Arabidopsis thaliana (AtDGAT1). This comparison of DGATs indicates that Rc DGAT1 is more active than AtDGAT1 when the substrate is diricinolein, the predominant substrate for DGAT in the castor seed, while both are similarly active with dipalmitolein. The approximate twofold preference of RcDGAT in using diricinolein explains part of the sixfold preference displayed by a castor in vitro system for incorporating ricinoleate into castor oil.