ATP/GTP hydrolysis is required for oxazole and thiazole biosynthesis in the peptide antibiotic microcin B17

The product of the mcbA gene of Escherichia coli is altered postranslationally by the multimeric Microcin synthetase complex to cyclize four Cys and four Ser residues to four thiazoles and four oxazoles, respectively, in the maturation of the antibiotic Microcin B17. Mutagenesis of three aspartates to alanine in motifs of the McbD subunit reduced Microcin b17 production in vivo and heterocycle formation in vitro. This indicates that the 45 kDa McbD has a regulated ATPase/GTPase domain in its N-terminal region needed for peptide heterocyclization.