Supporting information: Chemical synthesis of trans 8-methyl-6-nonenoyl-CoA and functional expression unravel capsaicin synthase activity encoded by the Pun1 locus

Although the capsaicinoid biosynthetic pathway has been investigated for decades, several biosynthetic steps have remained partly hypothetical. Genetic evidence suggested that the decisive capsaicin synthase is encoded by the Pun1 locus.

Yet, genetic evidence of the Pun1 locus was never corroborated by functionally active capsaicin synthase that presumably catalyzes amide bond formation between trans 8-methyl-6-nonenoyl-CoA derived from branched chain amino acid biosynthesis and vanilloylamine derived from the phenylpropanoid pathway. In this report, we demonstrate enzymatic activity of a recombinant capsaicin synthase encoded by Pun1, functionally expressed in E. coli, and provide information on substrate specificity and catalytic properties.