Identification of a bacteria-produced benzisoxazole with antibiotic activity against multi-drug resistant Acinetobacter baumannii

J Antibiot (Tokyo). 2021 Jun;74(6):370-380. doi: 10.1038/s41429-021-00412-7. Epub 2021 Feb 12.

Abstract

The emergence of multi-drug resistant pathogenic bacteria represents a serious and growing threat to national healthcare systems. Most pressing is an immediate need for the development of novel antibacterial agents to treat Gram-negative multi-drug resistant infections, including the opportunistic, hospital-derived pathogen, Acinetobacter baumannii. Herein we report a naturally occurring 1,2-benzisoxazole with minimum inhibitory concentrations as low as 6.25 μg ml-1 against clinical strains of multi-drug resistant A. baumannii and investigate its possible mechanisms of action. This molecule represents a new chemotype for antibacterial agents against A. baumannii and is easily accessed in two steps via de novo synthesis. In vitro testing of structural analogs suggest that the natural compound may already be optimized for activity against this pathogen. Our results demonstrate that supplementation of 4-hydroxybenzoate in minimal media was able to reverse 1,2-benzisoxazole's antibacterial effects in A. baumannii. A search of metabolic pathways involving 4-hydroxybenzoate coupled with molecular modeling studies implicates two enzymes, chorismate pyruvate-lyase and 4-hydroxybenzoate octaprenyltransferase, as promising leads for the target of 3,6-dihydroxy-1,2-benzisoxazole.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter baumannii / drug effects*
  • Anti-Bacterial Agents / chemistry*
  • Anti-Bacterial Agents / metabolism
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / antagonists & inhibitors
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Bradyrhizobium / metabolism
  • Drug Antagonism
  • Drug Resistance, Multiple, Bacterial / drug effects
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology
  • Microbial Sensitivity Tests
  • Molecular Docking Simulation
  • Molecular Structure
  • Oxo-Acid-Lyases / antagonists & inhibitors
  • Oxo-Acid-Lyases / chemistry
  • Oxo-Acid-Lyases / metabolism
  • Parabens / pharmacology
  • Pseudomonas aeruginosa / drug effects

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Enzyme Inhibitors
  • Parabens
  • Oxo-Acid-Lyases
  • chorismate pyruvate lyase
  • 4-hydroxybenzoic acid

Supplementary concepts

  • Bradyrhizobium denitrificans