Submitted to: United States Japan Natural Resources Protein Panel
Publication Type: Proceedings
Publication Acceptance Date: November 4, 2002
Publication Date: December 1, 2002
Citation: Pepperman Jr, A.B., Dyer, J.M., Kuan, J.W., Chapital, D.C. 2002. Unusual Fatty Acids Produced by Microbial Expression of Enzymes from the Tung Tree. In: Proceedings of the United States-Japan Cooperative Program in Natural Resources (UJNR) Protein Resources Panel. Cherry, J.P. and Pavlath, A.E. (eds.). Eastern Regional Research Center, Wyndmoor, PA. p. Q1-Q7. Technical Abstract: Tung oil, produced by fruit of the tung tree (Aleurites fordii), is a valuable industrial oil used in formulations of inks, dyes, coatings, and resins. The fruit contains all of the genes and enzymes required for synthesis of the oil, and such enzymes could be used for conversion of low-cost vegetable oils into value added drying oils. Using molecular biological techniques, we have isolated, characterized, and cloned the genes responsible for the production of eleostearic acid. The cofactor proteins required by these enzymes have been identified, their activity characterized and subcellular location determined. Expression of the eleostearic acid biosynthetic gene (tFADX) in Baker's yeast (Saccharomyces cerevisiae) produced the enzyme and converted linoleic acid to eleostearic acid, confirming its role in eleostearic acid biosynthesis. This unique microbial expression system was developed for modifying oils and is based upon the consumption of lipids by common baker's yeast and modification of the lipids by enzymes transgenically-expressed within the yeast cells. Linoleic acid was included in the growth media for this expressed within the yeast cells. Linoleic acid was included in the growth media for this experiment, since linoleic acid is not normally produced by yeast cells. The activity of tFADX was further characterized by culturing yeast in the presence of a variety of other fatty acids. The tFADX enzyme showed remarkable enzymatic plasticity, converting a variety of different fatty acids into conjugated fatty acid products. However, the amount of eleostearic acid synthesized in yeast cells is quite low (about 2% of fatty acid composition), and optimization of tung enzymes and identification of the accessory proteins as well as a better understanding of how these enzymes are regulated are the object of present studies.