Structural Basis of Amide-Forming Adenylation Enzyme VinM in Vicenistatin Biosynthesis.

Adenylation enzymes activate amino acid substrates to aminoacyl adenylates and generally transfer this moiety onto the thiol group of the phosphopantetheine arm of a carrier protein for the selective incorporation of aminoacyl building blocks in natural product biosynthesis. In contrast to the canonical thioester-forming adenylation enzymes, the amide-forming adenylation enzyme VinM transfers an l-alanyl group onto the amino group of the aminoacyl unit attached to the phosphopantetheine arm of the carrier protein VinL to generate dipeptidyl-VinL in vicenistatin biosynthesis. It is unclear how VinM distinguishes aminoacyl-VinL from VinL for amide bond formation.