Characterization of Acyl-CoA Oxidases from the Lipolytic Yeast SH14.

The lipolytic yeast SH14 contains three Acyl-CoA oxidases (ACOXs) which are encoded by the , , and genes and catalyze the first reaction in the β-oxidation of fatty acids. Here, the respective functions of the three isozymes were studied by growth analysis of mutant strains constructed by a combination of three mutations in minimal medium containing fatty acid as the sole carbon source. Substrate specificity of the isozymes was analyzed using recombinant SH14 strains overexpressing the respective genes. isozyme showed substrate specificity toward short- and medium-chain fatty acids (C6-C12), while isozyme preferred long-chain fatty acid longer than C12. isozyme revealed a preference for a broad substrate spectrum from C6-C16. Although the substrate specificity of and covers medium- and long-chain fatty acids, these two isozymes were insufficient for complete β-oxidation of long-chain fatty acids, and therefore was indispensable.