An unexpected split-merge pathway to the symmetric nonribosomal peptide antibiotic closthioamide.

Dunbar KL, Dell M, Molloy EM, Büttner H, Kumpfmüller J, Hertweck C (2020) An unexpected split-merge pathway to the symmetric nonribosomal peptide antibiotic closthioamide. Angew Chem Int Ed 60(8), 4104-4109.

Abstract

Closthioamide (CTA) is a symmetric nonribosomal peptide (NRP) comprised of two diaminopropane-linked polythioamidated monomers. CTA is biosynthesized by Ruminiclostridium cellulolyticum via an atypical NRP synthetase (NRPS)-independent biosynthetic pathway. Although the logic for monomer assembly was recently elucidated, the strategy for the biosynthesis and incorporation of the diamine linker remained a mystery. By means of genome editing, synthesis, and in vitro biochemical assays, we demonstrate that the final steps in CTA maturation proceed through a surprising split-merge pathway involving the dual use of a thiotemplated intermediate. This pathway includes the first examples of an aldo-keto reductase catalyzing the reductive release of a thiotemplated product, and of a transthioamidating transglutaminase. In addition to clarifying the remaining steps in CTA assembly, our data shed light on largely unexplored pathways for NRPS-independent peptide biosynthesis.

Leibniz-HKI-Authors

Christian Hertweck
Jana Krabbe
Kyle Dunbar
Evelyn Molloy
Maria Dell
Hannah Büttner

Identifier

doi: 10.1002/anie.202011741

PMID: 33119936