Structures and functions of nonribosomal and non-nonribosomal peptide synthetases Martin Schmeing McGill University, Canada Nonribosomal peptide synthetases (NRPSs) are true macromolecular machines, having modular assembly-line logic, a complex catalytic cycle, moving parts and many active sites. We have performed structural and functional analyses of components of the NRPS systems responsible for the syntheses of the antibiotic gramicidin, the anti-algae bacillamide, the anti-cancer agent valinomycin and the novel compound maxibactin. Results from these studies provide insight into the superdomain and supermodular architecture, conformational changes and mechanisms of tailoring that NRPSs use to synthesize their important bio-active products. In addition, we have performed structural and functional characterization of the non-NRPS enzyme cyanophycin synthetase. Cyanophycin is a natural biopolymer consisting of a chain of poly-L-Asp residues with L-Arg residues attached to the carboxylate side chains by isopeptide bonds. It is used in a wide range of bacteria for cellular nitrogen storage. Our studies reveal how activities from three domains combine to allow elegant processive polymerization of long chains of cyanophycin.
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© The Author(s), 2022
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