Genomic scanning enabling discovery of a new antibacterial bicyclic carbamate-containing alkaloid

Qing Fang, Linrui Wu, Caroline Urwald* (Corresponding Author), Morgane Mugat (Corresponding Author), Shan Wang, Kwaku Kyeremeh, Carol Philips, Samantha Law, Yongjun Zhou, Hai Deng* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Non-ribosomal peptides are a group of structurally diverse natural products with various important therapeutic and agrochemical applications. Bacterial pyrrolizidine alkaloids (PAs), containing a scaffold of two fused five-membered ring system with a nitrogen atom at the bridgehead, have been found to originate from a multidomain non-ribosomal peptide synthetase to generate indolizidine intermediates, followed by multistep oxidation, catalysed by single Bayer-Villiger (BV) enzymes, to yield PA scaffolds. Although bacterial PAs are rare in natural product inventory, bioinformatics analysis suggested that the biosynthetic gene clusters (BGCs) that are likely to be responsible for the production of PA-like metabolites are widely distributed in bacterial genomes. However, most of the strains containing PA-like BGCs are not deposited in the public domain, therefore preventing further assessment of the chemical spaces of this group of bioactive metabolites. Here, we report a genomic scanning strategy to assess the potential of PA metabolites production in our culture collection without prior knowledge of genome information. Among the strains tested, we found fifteen contain the key BV enzymes that are likely to be involved in the last step of PA ring formation. Subsequently one-strain-many-compound (OSMAC) method, supported by a combination of HR-MS, NMR, SMART 2.0 technology, and GNPS analysis, allowed identification and characterization of a new [5 + 7] heterobicyclic carbamate, legoncarbamate, together with five known PAs, bohemamine derivatives, from Streptomyces sp. CT37, a Ghanaian soil isolate. The absolute stereochemistry of legoncarbamate was determined by comparison of measured and calculated ECD spectra. Legoncarbamate displays antibacterial activity against E. coli ATCC 25922 with an MIC value of 3.1 μg/mL. Finally, a biosynthetic model of legoncarbamate and other bohemamines was proposed based on the knowledge we have gained so far.

Original languageEnglish
Pages (from-to)12-19
Number of pages8
JournalSynthetic and Systems Biotechnology
Volume6
Issue number1
Early online date20 Jan 2021
DOIs
Publication statusPublished - Mar 2021

Keywords

  • Genomic scanning
  • Bayer villiger monooxygenase
  • Carbamate alkaloids
  • pyrrolizidine alkaloids
  • non-ribosomal peptide synthetases

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