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)-α-pyrones by sequential condensation with malonyl-CoA.
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Zha, W., Rubin-Pitel, S.B. and Zhao, H. Characterization of the substrate specificity of PhlD, a type III polyketide synthase from Pseudomonas fluorescens. J. Biol. Chem.281 (2006) 32036–32047. [DOI] [PMID: 16931521]