A Mechanistic Model for Colibactin-Induced Genotoxicity

Alan Healy, Herman Nikolayevskiy, Jaymin R. Patel, Jason M. Crawford, Seth B. Herzon

Research output: Contribution to journalArticle

Abstract

Precolibactins and colibactins represent a family of natural products that are encoded by the clb gene cluster and are produced by certain commensal, extraintestinal, and probiotic E. coli. clb+ E. coli induce megalocytosis and DNA double-strand breaks in eukaryotic cells, but paradoxically, this gene cluster is found in the probiotic Nissle 1917. Evidence suggests precolibactins are converted to genotoxic colibactins by colibactin peptidase (ClbP)-mediated cleavage of an N-acyl-d-Asn side chain, and all isolation efforts have employed ΔclbP strains to facilitate accumulation of precolibactins. It was hypothesized that colibactins form unsaturated imines that alkylate DNA by cyclopropane ring opening (2 → 3). However, as no colibactins have been isolated, this hypothesis has not been tested experimentally. Additionally, precolibactins A-C (7-9) contain a pyridone that cannot generate the unsaturated imines that form the basis of this hypothesis. To resolve this, we prepared 13 synthetic colibactin derivatives and evaluated their DNA binding and alkylation activity. We show that unsaturated imines, but not the corresponding pyridone derivatives, potently alkylate DNA. The imine, unsaturated lactam, and cyclopropane are essential for efficient DNA alkylation. A cationic residue enhances activity. These studies suggest that precolibactins containing a pyridone are not responsible for the genotoxicity of the clb cluster. Instead, we propose that these are off-pathway fermentation products produced by a facile double cyclodehydration route that manifests in the absence of viable ClbP. The results presented herein provide a foundation to begin to connect metabolite structure with the disparate phenotypes associated with clb+ E. coli.

Original languageEnglish (US)
Pages (from-to)15563-15570
Number of pages8
JournalJournal of the American Chemical Society
Volume138
Issue number48
DOIs
StatePublished - Dec 7 2016

Fingerprint

DNA
Imines
Pyridones
Escherichia coli
Alkylation
Probiotics
Genes
Multigene Family
Derivatives
Peptide Hydrolases
Metabolites
Fermentation
Lactams
Double-Stranded DNA Breaks
Eukaryotic Cells
colibactin
Biological Products
Phenotype
cyclopropane

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Healy, A., Nikolayevskiy, H., Patel, J. R., Crawford, J. M., & Herzon, S. B. (2016). A Mechanistic Model for Colibactin-Induced Genotoxicity. Journal of the American Chemical Society, 138(48), 15563-15570. https://doi.org/10.1021/jacs.6b10354

A Mechanistic Model for Colibactin-Induced Genotoxicity. / Healy, Alan; Nikolayevskiy, Herman; Patel, Jaymin R.; Crawford, Jason M.; Herzon, Seth B.

In: Journal of the American Chemical Society, Vol. 138, No. 48, 07.12.2016, p. 15563-15570.

Research output: Contribution to journalArticle

Healy, A, Nikolayevskiy, H, Patel, JR, Crawford, JM & Herzon, SB 2016, 'A Mechanistic Model for Colibactin-Induced Genotoxicity', Journal of the American Chemical Society, vol. 138, no. 48, pp. 15563-15570. https://doi.org/10.1021/jacs.6b10354
Healy, Alan ; Nikolayevskiy, Herman ; Patel, Jaymin R. ; Crawford, Jason M. ; Herzon, Seth B. / A Mechanistic Model for Colibactin-Induced Genotoxicity. In: Journal of the American Chemical Society. 2016 ; Vol. 138, No. 48. pp. 15563-15570.
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