Escherichia coli N-Acetylglucosamine-1-Phosphate-Uridyltransferase/Glucosamine-1-Phosphate-Acetyltransferase (GlmU) Inhibitory Activity of Terreic Acid Isolated from Aspergillus terreus

J Biomol Screen. 2016 Apr;21(4):342-53. doi: 10.1177/1087057115625308. Epub 2016 Jan 13.

Abstract

Secondary metabolite of Aspergillus terreus, terreic acid, is a reported potent antibacterial that was identified more than 60 years ago, but its cellular target(s) are still unknown. Here we screen its activity against the acetyltransferase domain of a bifunctional enzyme, Escherichia coli N-acetylglucosamine-1-phosphate-uridyltransferase/glucosamine-1-phosphate-acetyltransferase (GlmU). An absorbance-based assay was used to screen terreic acid against the acetyltransferase activity of E. coli GlmU. Terreic acid was found to inhibit the acetyltransferase domain of E. coli GlmU with an IC50 of 44.24 ± 1.85 µM. Mode of inhibition studies revealed that terreic acid was competitive with AcCoA and uncompetitive with GlcN-1-P. It also exhibited concentration-dependent killing of E. coli ATCC 25922 up to 4× minimum inhibitory concentration and inhibited the growth of biofilms generated by E. coli. Characterization of resistant mutants established mutation in the acetyltransferase domain of GlmU. Terreic acid was also found to be metabolically stable in the in vitro incubations with rat liver microsome in the presence of a NADPH regenerating system. The studies reported here suggest that terreic acid is a potent antimicrobial agent and support that E. coli GlmU acetyltransferase is a molecular target of terreic acid, resulting in its antibacterial activity.

Keywords: ESBL; GlmU; acetyltransferase; drug resistance; lipopolysaccharide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetyl Coenzyme A / chemistry
  • Acetyl Coenzyme A / metabolism
  • Animals
  • Anti-Bacterial Agents / isolation & purification
  • Anti-Bacterial Agents / pharmacology*
  • Aspergillus / chemistry*
  • Aspergillus / metabolism
  • Binding, Competitive
  • Biofilms / drug effects*
  • Biofilms / growth & development
  • Biological Assay
  • Enzyme Inhibitors / isolation & purification
  • Enzyme Inhibitors / pharmacology*
  • Escherichia coli / drug effects*
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Escherichia coli / growth & development
  • Escherichia coli Proteins / antagonists & inhibitors*
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Gene Expression
  • Glucosamine / analogs & derivatives
  • Glucosamine / chemistry
  • Glucosamine / metabolism
  • Glucose-6-Phosphate / analogs & derivatives
  • Glucose-6-Phosphate / chemistry
  • Glucose-6-Phosphate / metabolism
  • Microbial Sensitivity Tests
  • Microsomes, Liver / drug effects
  • Microsomes, Liver / metabolism
  • Molecular Docking Simulation
  • Multienzyme Complexes / antagonists & inhibitors*
  • Multienzyme Complexes / chemistry
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism
  • Mutation
  • Protein Binding / drug effects
  • Protein Domains
  • Quinones / isolation & purification
  • Quinones / pharmacology
  • Rats
  • Secondary Metabolism

Substances

  • Anti-Bacterial Agents
  • Enzyme Inhibitors
  • Escherichia coli Proteins
  • GlmU protein, E coli
  • Multienzyme Complexes
  • Quinones
  • glucosamine 6-phosphate
  • Glucose-6-Phosphate
  • Acetyl Coenzyme A
  • Glucosamine
  • terreic acid