In order for yeast to utilize fatty acids, either as an energy source (via beta-oxidation) or for essential processes such as phospholipid biosynthesis and protein myristoylation, the fatty acids must first be converted into activated intermediates, acyl-CoAs, through thioesterification of fatty acids with coenzyme A. When fatty acids are synthesized de novo, activation is part of the process of synthesis and is accomplished by the same fatty acid synthetase complex (Fas1p-Fas2p) that initiates and elongates the fatty acid chain. However, yeast cells can also utilize exogenous, imported fatty acids, an ability that becomes essential if the fatty acid synthetase complex is inactivated by mutation or specific inhibitors such as cerulenin. These exogenous fatty acids are activated by one of five characterized yeast acyl-CoA synthetases: Faa1p, Faa2p, Faa3p, Faa4p, or Fat1p (see 5 and 6 for review).

FAA2 encodes a peroxisomal acyl-CoA synthetase with broad substrate activity in vitro (C6:0-C20:0), but the highest activity on medium chain fatty acids (C9:0-C13:0) (3, 2). Genetic evidence indicates that Faa2p is also capable of activating very long chain fatty acids, such as lignoceric acid (C24:0) (7).

Last updated: 2010-02-11