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Acyl Donor Stringency and Dehydroaminoacyl Intermediates in β-Lactam Formation by a Non-ribosomal Peptide Synthetase.

ABSTRACT: Condensation (C) domains in non-ribosomal peptide synthetases catalyze peptide elongation steps whereby activated amino acid or peptidyl acyl donors are coupled with specific amino acid acceptors. In the biosynthesis of the β-lactam antibiotic nocardicin A, an unusual C domain converts a seryl tetrapeptide into its pentapeptide product containing an integrated β-lactam ring. While indirect evidence for the intermediacy of a dehydroalanyl species has been reported, here we describe observation of the elusive enzyme-bound dehydroamino acyl intermediate generated from the corresponding allo-threonyl tetrapeptide and partitioned into pentapeptide products containing either a dehydrobutyrine residue or an embedded β-lactam. Contrary to trends in the literature where condensation domains have been deemed flexible as to acyl donor structure, this β-lactam synthesizing domain is highly discriminating. The observation of dehydrobutyrine formation links this C domain to related clades associated with natural products containing dehydroamino acid and d-configured residues, suggesting a common mechanistic link.

SUBMITTER: Long DH

PROVIDER: S-EPMC8211430 | biostudies-literature |

REPOSITORIES: biostudies-literature

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?-Lactam formation by a non-ribosomal peptide synthetase during antibiotic biosynthesis.

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A conserved tyrosyl-glutamyl catalytic dyad in evolutionarily linked enzymes: carbapenam synthetase and beta-lactam synthetase.

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