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Synthetic peptides derived from the sequence of a lasso peptide microcin J25 show antibacterial activity

Rania Soudy1, Liru Wang, Kamaljit Kaur

  • 1Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada.

Bioorganic & Medicinal Chemistry
|February 7, 2012
PubMed

Insights

Synthetic microcin J25 derivatives were created, with two showing bactericidal activity against Salmonella. Peptide 1 effectively targets resistant strains by inhibiting bacterial respiration, demonstrating low mammalian toxicity.

Area of Science:

  • Microbiology
  • Biochemistry
  • Peptide Synthesis

Background:

  • Microcin J25 (MccJ25) is a ribosomally synthesized antibacterial peptide known for its unique and stable lasso structure.
  • The lasso conformation of MccJ25 is crucial for its stability and is formed with the help of specific processing enzymes.

Purpose of the Study:

  • To synthesize novel MccJ25 derivatives designed for folded conformations via disulfide bonds and non-covalent interactions.
  • To evaluate the antibacterial activity, mechanism of action, and toxicity of these synthetic MccJ25 analogs.

Main Methods:

  • Chemical synthesis of six MccJ25-derived peptides.
  • Antibacterial assays against Salmonella strains, including MccJ25-resistant ones.
  • Solution conformation studies and stability assessments.
  • Respiration inhibition assays and mammalian cell toxicity tests.

Main Results:

  • Two synthetic peptides, 1 and 6, exhibited bactericidal activity against Salmonella newport, representing the first synthetic bactericidal MccJ25 derivatives.
  • Peptide 1 demonstrated potent activity against multiple Salmonella strains, including resistant strains, and was found to inhibit bacterial respiration.
  • Active peptides did not adopt the lasso conformation, and all tested derivatives showed minimal toxicity to mammalian cells.

Conclusions:

  • Synthetic MccJ25 derivatives can be bactericidal and retain low mammalian toxicity.
  • Peptide 1's antimicrobial activity is mediated by respiration inhibition, independent of the lasso structure.
  • These findings open avenues for developing new peptide-based antibiotics targeting bacterial infections.

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