Poster: Lipids & related molecules

Abs # 307: The Characterization of Fatty Acid Synthesis in Schizochytrium sp.

Presenter:	Hauvermale, Amber , ahauvermale@martekbio.com
Authors	Hauvermale, Amber  (A) (B)  Kuner, Jerry  (A)   Weaver, Craig  (A)   Rosenzweig, Brad  (A)   Milhollan, Jessica  (B)   Guerra, Daniel  (B)   Metz, Jim  (A)
Affiliations:	(A): Martek Biosciences Corporation (B): The University of Colorado at Colorado Springs

Schizochytrium sp., is a marine micro-alga that has been developed as a commercial source for oil enriched in docosahexaenoic acid (DHA 22:6 n-3). Omega-3 fatty acids such as DHA are recognized for their implicated benefits in cardiovascular disease, neural development and infant health. Previous work suggested that DHA synthesis in Schizochytrium occurs via a dedicated polyunsaturated fatty acid synthase (PUFA synthase) rather than by elongation and desaturation of shorter chain saturated fatty acids (Metz et al., Science 2001). Here we present additional data about fatty acid synthesis in Schizochytrium. First, three classical inhibitors (triclosan, cerulenin, and thiolactomycin) were tested to determine their effects on ¹⁴C acetate incorporation into various fatty acids. Results of these experiments revealed a differential inhibition by cerulenin on short chain fatty acid synthesis. Second, the gene encoding the short chain fatty acid synthase (FAS) was cloned and characterized. Based on the domain organization, Schizochytrium FAS resembles a fusion of yeast FAS β and α subunits. Third, targeted disruption of the cloned FAS gene produced a lethal saturated fatty acid auxotroph. Finally, in vitro assays using both the FAS knockout and PUFA synthase knockout strains demonstrated the FAS and PUFA synthase operate independently in Schizochytrium. The data from these experiments show that the products of the FAS are not utilized for DHA synthesis.