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Antimicrobial properties of the Escherichia coli R1 plasmid host killing peptide

Douglas C Pecota1, George Osapay, Michael E Selsted

  • 1Department of Chemical Engineering, University of Connecticut, Storrs 06269-3222, USA.

Journal of Biotechnology
|November 5, 2002
PubMed

Insights

Synthetic host killing peptide (Hok) from E. coli plasmid R1 was created. While Hok did not kill microbes externally, electroporation demonstrated its potent cell-killing ability, especially in E. coli.

Area of Science:

  • Molecular Biology
  • Microbiology
  • Biochemistry

Background:

  • The host killing peptide (Hok) is part of the hok/sok post-segregational killer system in Escherichia coli plasmid R1.
  • Hok functions by depolarizing the cytoplasmic membrane to induce cell death when present in the cytosol.

Purpose of the Study:

  • To synthesize the 52 amino acid Hok peptide using Fmoc chemistry.
  • To evaluate the cell-killing activity of the synthesized Hok peptide and its fragments against various microorganisms.

Main Methods:

  • Solid-phase peptide synthesis using Fmoc chemistry.
  • Mass spectrometry for molecular weight confirmation.
  • Exposure of microorganisms to purified Hok peptide and its fragments, including electroporation and heat shock treatments.

Main Results:

  • Purified Hok peptide showed no significant killing effect on six tested microorganisms when applied externally.
  • Electroporation of Hok into Escherichia coli and Pseudomonas putida resulted in substantial cell death (100,000-fold and 500-fold reductions, respectively).
  • Specific Hok fragments (Hok(1-28), Hok(16-52), and Hok(31-52)) also exhibited cell-killing activity upon electroporation into E. coli.

Conclusions:

  • The synthetic Hok peptide is capable of killing bacterial cells, particularly when introduced intracellularly via electroporation.
  • The study confirms the cytotoxic potential of Hok and its fragments, suggesting intracellular delivery as a key mechanism for its activity.

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