S53: Amide bond formation in the biosynthesis of capuramycin antibiotics

Capuramycins are nucleoside antibiotics targeting bacterial translocase I involved in peptidoglygcan cell wall biosynthesis. The biosynthetic gene clusters for three different capuramycins have been cloned and sequenced to reveal a minimum of 23 shared open reading frames (orfs) involved in the biosynthesis, regulation, and resistance of these compounds. Of these shared orfs are two potential genes encoding proteins typically involved in resistance to antibiotics, an aminoglycoside-3-phosphotransferase (CapP) and a class C Β-lactamase (CapW). As expected, CapP is demonstrated to function as an ATP-dependent capuramycin-3''-phosphotransferase involved in self-resistance. In contrast, CapW is unexpectedly shown to catalyze an amide-ester exchange reaction to generate one of the two amide bonds of capuramycins. Along with additional results to be presented, the data for CapW estabish a new mechanism of amide formation in antibiotic biosynthesis.