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Tripropeptin C blocks the lipid cycle of cell wall biosynthesis by complex formation with undecaprenyl pyrophosphate

Hideki Hashizume1, Ryuichi Sawa, Shigeko Harada

  • 1Drug Development Unit, Bioactive Molecule Research Group, Laboratory of Disease Biology, Institute of Microbial Chemistry, Tokyo, Japan. hashizumeh@bikaken.or.jp

Antimicrobial Agents and Chemotherapy
|June 2, 2011
PubMed

Insights

Tripropeptin C (TPPC) is a novel cyclic lipodepsipeptide antibiotic effective against resistant bacteria like MRSA. It disrupts bacterial cell wall synthesis by inhibiting undecaprenyl pyrophosphate dephosphorylation and potentially other key steps.

Area of Science:

  • Microbiology
  • Biochemistry
  • Drug Discovery

Background:

  • Antibiotic resistance is a growing global health threat, necessitating the discovery of new antimicrobial agents.
  • Naturally occurring compounds offer a promising source for novel antibiotics with unique mechanisms of action.
  • Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and penicillin-resistant Streptococcus pneumoniae are critical pathogens with limited treatment options.

Purpose of the Study:

  • To investigate the antibacterial activity and mechanism of action of Tripropeptin C (TPPC), a cyclic lipodepsipeptide antibiotic.
  • To elucidate the specific molecular targets and pathways inhibited by TPPC in bacterial pathogens.
  • To compare the mode of action of TPPC with existing antibiotics.

Main Methods:

  • Antibacterial susceptibility testing against resistant bacterial strains (MRSA, VRE, S. pneumoniae).
  • Enzyme inhibition assays to determine the IC(50) for peptidoglycan synthesis and C(55)-PP phosphatase activity.
  • Cellular accumulation studies using mass spectrometry and thin-layer chromatography to analyze metabolic intermediates.
  • In vitro biochemical assays to assess interactions with undecaprenyl pyrophosphate (C(55)-PP).

Main Results:

  • TPPC demonstrated potent activity against MRSA, VRE, and penicillin-resistant S. pneumoniae.
  • TPPC inhibited N-acetylglucosamine incorporation into peptidoglycan and caused cytoplasmic accumulation of UDP-MurNAc-pentapeptide.
  • TPPC directly interacted with C(55)-PP, inhibiting C(55)-PP phosphatase activity with an IC(50) of 0.03–0.1 μM.
  • TPPC treatment led to C(55)-PP accumulation and inhibition of transglycosylation or flippase activity.

Conclusions:

  • TPPC represents a novel class of antibiotics targeting bacterial cell wall synthesis through a unique multi-step inhibition mechanism.
  • Its distinct mode of action, involving C(55)-PP phosphatase inhibition and potential downstream effects, differentiates it from current antibiotics.
  • TPPC holds potential as a therapeutic agent against multidrug-resistant bacterial infections.

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