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Nanomechanics of Drug-target Interactions and Antibacterial Resistance Detection
11:56

Nanomechanics of Drug-target Interactions and Antibacterial Resistance Detection

Published on: October 25, 2013

Peptidoglycan structure of Enterococcus faecium expressing vancomycin resistance of the VanB type

D Billot-Klein1, D Shlaes, D Bryant

  • 1L.R.M.A., Paris, France.

The Biochemical Journal
|February 1, 1996
PubMed

Insights

Enterococci resistance to glycopeptide antibiotics involves altered peptidoglycan precursors. Vancomycin presence interferes with cell wall oligomer synthesis in resistant Enterococcus faecium strains.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Enterococci exhibit resistance to glycopeptide antibiotics, a critical clinical challenge.
  • This resistance mechanism involves the substitution of UDP-MurNAc-pentapeptide with UDP-MurNAc-tetrapeptide-D-lactate in peptidoglycan synthesis.

Purpose of the Study:

  • To elucidate the peptidoglycan structures in inducible (VanB-type) and constitutive glycopeptide-resistant Enterococcus faecium.
  • To investigate the impact of vancomycin on cell wall precursor processing in resistant strains.

Main Methods:

  • High-performance liquid chromatography (HPLC) for muropeptide identification.
  • Mass spectrometry (MS) and amino acid analysis for structural determination of muropeptides.
  • Analysis of Enterococcus faecium strains D366 (inducible resistance) and MT9 (constitutive resistance).

Main Results:

  • Identified 17 muropeptides in both resistant and non-resistant states, with 15 structures determined.
  • The cross-bridge between D-alanine and L-lysine was found to be a single asparagine.
  • No free monomer pentapeptide or tetrapeptide-D-lactate precursors were detected.
  • Enterococcus faecium cell wall machinery efficiently processed the D-lactate precursor in the absence of vancomycin.
  • Subinhibitory concentrations of vancomycin interfered with oligomer synthesis.

Conclusions:

  • The cell wall synthetic machinery of Enterococcus faecium can efficiently utilize the D-lactate precursor when vancomycin is absent.
  • Vancomycin, even at subinhibitory concentrations, significantly impacts peptidoglycan oligomer synthesis in resistant strains.
  • These findings provide insights into the molecular mechanisms of glycopeptide resistance in enterococci.

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