Prescopranone is a key intermediate in the biosynthesis of scopranones.[1] Prescopranone is the precursor to scopranone A, scopranone B, and scopranone C, which are produced by Streptomyces sp. BYK-11038.
The biosynthesis of prescopranone follows the module structure of a Type I polyketide synthase(PKS) with three elongation modules and a lactonizing thioesterase domain. Genome mining of Streptomyces sp. BYK identified a scopranone biosynthetic gene cluster containing 3 genes, sprA, sprB, and sprC, that encode modular PKSs.[2]
A starter acyl carrier protein is loaded with malonyl-CoA, and decarboxylated by a ketosynthase (KSQ). The starter unit is then transferred to module 1, which elongates the polyketide chain with ethyl malonyl-CoA. The tailoring domain of this module reduces the β-carbonyl to an alkene. Module 2 elongates the polyketide with ethylbutyl-malonyl-CoA. Finally, module 3 elongates the polyketide chain with ethyl malonyl-CoA, and is released upon the lactonization of the polyketide product by a thioesterase domain. Following the cyclization and release of the polyketide, the product undergoes a keto-enol tautomerism to form prescopranone.Both modules 2 and 3 contain dysfunctional ketoreductase (KR) domains, which do not reduce the β-carbonyl due to missing NAD(P)H binding motifs and tyrosine residues in their active sites.Prescopranone undergoes post-PKS transformations to form scopranones. Additionally, the deletion of a downstream gene sprT can disrupt biosynthesis of scopranones in Streptomyces avermitilis SUKA54. The products of this mutated pathway have yet to be elucidated.[3]
Prescopranone and similar compounds are currently being investigated as bone morphogenetic protein (BMP) inhibitors for the treatment of fibrodysplasia ossificans progressiva (FOP).