One-Step Transformation of Coenzyme A into Analogues by Transamidation

Several coenzyme A (CoA) analogues are made in a single step under mild conditions via transamidation reactions catalyzed by boric acid in water. This approach offers rapid access to compounds useful for the study of a wide spectrum of enzyme catalyzed reactions, especially processes involving acyl carrier proteins (ACP) of polyketide synthases (PKS), fatty acid synthases (FAS), and nonribosomal peptide synthetases (NRPS). The CoA analogues presented are readily elaborated or extended by precedented reactions for specific applications that may be required

Understanding Programming of Fungal Iterative Polyketide Synthases: The Biochemical Basis for Regioselectivity by the Methyltransferase Domain in the Lovastatin Megasynthase

Highly reducing polyketide synthases (HR-PKSs) from fungi synthesize complex natural products using a single set of domains in a highly programmed, iterative fashion. The most enigmatic feature of HR-PKSs is how tailoring domains function selectively during different iterations of chain elongation to afford structural diversity. Using the lovastatin nonaketide synthase LovB as a model system and a variety of acyl substrates, we characterized the substrate specificity of the LovB methyltransferase (MT) domain. We showed that, while the MT domain displays methylation activity toward different β-ketoacyl groups, it is exceptionally selective toward its naturally programmed β-keto-dienyltetraketide substrate with respect to both chain length and functionalization. Accompanying characterization of the ketoreductase (KR) domain displays broader substrate specificity toward different β-ketoacyl groups. Our studies indicate that selective modifications by tailoring domains, such as the MTs, are achieved by higher kinetic efficiency on a particular substrate relative to the rate of transformation by other competing domains