Increase in glutamine-non-amidated muropeptides in the peptidoglycan of vancomycin-resistant Staphylococcus aureus strain Mu50

J Antimicrob Chemother. 1998 Sep;42(3):315-20. doi: 10.1093/jac/42.3.315.


The peptidoglycan compositions of vancomycin-resistant Staphylococcus aureus (VRSA) strain Mu50 (MIC 8 mg/L) and hetero-VRSA strain Mu3 (MIC 3 mg/L) were compared in order to understand the mechanism of vancomycin resistance. As compared with Mu3, the cell wall of Mu50 had increased amounts of glutamine-non-amidated muropeptides and decreased cross-linking of peptidoglycan with a greatly decreased dimer/monomer ratio of muropeptides. In agreement with this observation, the peptidoglycan of Mu50 bound 1.4 times more vancomycin than that of Mu3. The increase in non-amidated muropeptides and the reduced cross-linking of the cell-wall peptidoglycan may contribute to the vancomycin resistance by increasing the consumption of vancomycin by the pre-existing cell wall of Mu50 and reducing the amount of vancomycin reaching the cytoplasmic membrane where the vital targets of the antibiotic are situated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / analysis
  • Drug Resistance, Microbial
  • Glutamine / chemistry
  • Glutamine / metabolism
  • Microbial Sensitivity Tests
  • Peptides / chemistry
  • Peptides / isolation & purification
  • Peptides / metabolism*
  • Peptidoglycan / chemistry
  • Peptidoglycan / metabolism*
  • Phenotype
  • Protein Conformation
  • Staphylococcus aureus / classification
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / metabolism*
  • Vancomycin / antagonists & inhibitors
  • Vancomycin / metabolism*
  • Vancomycin / pharmacology


  • Amino Acids
  • Peptides
  • Peptidoglycan
  • Glutamine
  • Vancomycin