Microbial biotransformation of DON: molecular basis for reduced toxicity

Sci Rep. 2016 Jul 6:6:29105. doi: 10.1038/srep29105.

Abstract

Bacteria are able to de-epoxidize or epimerize deoxynivalenol (DON), a mycotoxin, to deepoxy-deoxynivalenol (deepoxy-DON or DOM-1) or 3-epi-deoxynivalenol (3-epi-DON), respectively. Using different approaches, the intestinal toxicity of 3 molecules was compared and the molecular basis for the reduced toxicity investigated. In human intestinal epithelial cells, deepoxy-DON and 3-epi-DON were not cytotoxic, did not change the oxygen consumption or impair the barrier function. In intestinal explants, exposure for 4 hours to 10 μM DON induced intestinal lesions not seen in explants treated with deepoxy-DON and 3-epi-DON. A pan-genomic transcriptomic analysis was performed on intestinal explants. 747 probes, representing 323 genes, were differentially expressed, between DON-treated and control explants. By contrast, no differentially expressed genes were observed between control, deepoxy-DON and 3-epi-DON treated explants. Both DON and its biotransformation products were able to fit into the pockets of the A-site of the ribosome peptidyl transferase center. DON forms three hydrogen bonds with the A site and activates MAPKinases (mitogen-activated protein kinases). By contrast deepoxy-DON and 3-epi-DON only form two hydrogen bonds and do not activate MAPKinases. Our data demonstrate that bacterial de-epoxidation or epimerization of DON altered their interaction with the ribosome, leading to an absence of MAPKinase activation and a reduced toxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacteria / drug effects
  • Bacteria / genetics
  • Bacteria / metabolism*
  • Biotransformation*
  • Caco-2 Cells
  • Epithelial Cells / drug effects
  • Gene Expression Regulation / drug effects
  • Humans
  • Intestines / chemistry
  • Intestines / drug effects
  • Mitogen-Activated Protein Kinases / genetics*
  • Oxygen Consumption / genetics
  • Ribosomes / drug effects
  • Ribosomes / genetics
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Swine
  • Transcriptome / drug effects
  • Transcriptome / genetics
  • Trichothecenes / chemistry
  • Trichothecenes / toxicity*

Substances

  • Trichothecenes
  • deepoxy-deoxynivalenol
  • Mitogen-Activated Protein Kinases
  • deoxynivalenol