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MurD enzymes from different bacteria: evaluation of inhibitors

Hélène Barreteau1, Izidor Sosič, Samo Turk

  • 1Univ Paris-Sud, Laboratoire des Enveloppes Bactériennes et Antibiotiques, UMR 8619, Orsay, F-91405, France.

Biochemical Pharmacology
|June 19, 2012
PubMed

Insights

Antibacterial drug discovery targeting bacterial D-glutamic acid-adding enzyme (MurD ligase) showed varied efficacy. Most inhibitors effective against E. coli MurD were less potent against orthologues from other bacteria due to active site differences.

Area of Science:

  • Biochemistry
  • Microbiology
  • Drug Discovery

Background:

  • D-Glutamic acid-adding enzyme (MurD ligase) is crucial for bacterial cell-wall peptidoglycan synthesis.
  • MurD ligase is a significant target for developing novel antibacterial agents.
  • Previous research identified inhibitors for Escherichia coli MurD with IC50 values as low as 8 μM.

Purpose of the Study:

  • To evaluate the efficacy of known Escherichia coli MurD inhibitors against MurD enzymes from other bacterial species.
  • To investigate the potential for broad-spectrum antibacterial activity of these inhibitors.
  • To understand the structural basis for differential inhibition of MurD orthologues.

Main Methods:

  • In vitro biochemical assays were used to test the inhibitory activity of 20 selected compounds.
  • The compounds were tested against purified MurD ligase enzymes from Staphylococcus aureus, Streptococcus pneumoniae, Borrelia burgdorferi, and Mycobacterium tuberculosis.
  • Enzyme inhibition was quantified using IC50 values.

Main Results:

  • Most tested compounds showed reduced inhibitory efficiency against the MurD enzymes from Staphylococcus aureus, Streptococcus pneumoniae, Borrelia burgdorferi, and Mycobacterium tuberculosis compared to Escherichia coli.
  • Significant variations in IC50 values were observed across different bacterial orthologues.
  • The observed differences in inhibitor potency correlate with variations in the amino acid sequences and active site structures of the MurD ligases.

Conclusions:

  • The efficacy of MurD inhibitors is species-specific, limiting their potential as broad-spectrum antibacterial agents.
  • Structural differences in the active sites of MurD ligases from various bacteria contribute to differential drug responses.
  • Further research is needed to develop MurD inhibitors with broader antibacterial coverage or to design targeted therapies for specific pathogens.

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