John Browse and his coworkers at Washington State University focus on basic research to understand the biosynthesis and function of membrane and storage lipids in plants. However, Browse and James Spychalla have recently been awarded US Patent 6,884,921, which covers the production of a polypeptide with omega-3 desaturase in recombinant microorganisms or transgenic plants. The enzyme could be useful in manufacturing omega-3 fatty acids. Normally found mainly in wild salmon and other cold water fish, these compounds, especially arachidonic and eicosapentaenoic acids, find a market for nutritional and medical products.

The gene coding the omega-3 desaturase enzyme has an unusual origin. It is the fat-1 gene of Caenorhabditis elegans, a nematode widely used as a model in biochemical research. The researchers have been able to produce the gene's recombinant protein in Arabidopsis thaliana, a commonly used plant research model and Saccharomyces cerevisiae yeast. It could also be produced in a wide variety of other organisms, such as bacteria, cyanobacteria, phytoplankton, algae, fungi, plants, and animals.

The enzyme catalyzes the conversion of omega-6 fatty acids to omega-3 acids. Its presence in a cell causes the cell to have a greater proportion of omega-3 fatty acids in its lipids. One of the refinements of the technology is to transform the plant so that the enzyme is produced in its seed, which contains the plant oil. The enzyme can also be used to desaturate an omega-6 fatty acid that has been removed from the cell.

Browse's lab created a plasmid that could express the fat-1 gene in yeast, where an omega-6 fatty acyl substrate was available. Analysis showed that approximately 1% of the yeast cells' total fatty acids were 18:3, compared with less than 0.55% in untransformed yeast. Different combinations of promoters and yeast strains should make it possible to increase the yield of the omega-3 acids.

The patent is assigned to the university's tech transfer arm, Washington State University Research Foundation (Pullman, WA).

Details:

John A. Browse

Institute of Biological Chemistry

Washington State University

Pullman WA 99164-6340

Phone: 509-335-2293

Fax: 509-335-7643

E-mail: jab@wsu.edu

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