The enzyme, characterized from the bacterium Pseudomonas protegens Pf-5, is a type III polyketide synthase. The mechanism involves the cyclization of an activated 3,5-dioxoheptanedioate intermediate. The enzyme exhibits broad substrate specificity, and can accept C4-C12 aliphatic acyl-CoAs and phenylacetyl-CoA as the starter molecules, forming 6-(polyoxoalkyl)-alpha-pyrones by sequential condensation with malonyl-CoA.
