Influence of pH on the activity of thrombin-derived antimicrobial peptides

Research output: Contribution to journalArticle

Abstract

The wound environment is characterized by physiological pH changes. Proteolysis of thrombin by wound-derived proteases, such as neutrophil elastase, generates antimicrobial thrombin-derived C-terminal peptides (TCPs), such as HVF18 (HVFRLKKWIQKVIDQFGE). Presence of such TCPs in human wound fluids in vivo, as well as the occurrence of an evolutionarily conserved His residue in the primary amino acid sequence of TCPs, prompted us to investigate the pH-dependent antibacterial action of HVF18, as well as of the prototypic GKY25 (GKYGFYTHVFRLKKWIQKVIDQFGE). We show that protonation of this His residue at pH 5.5 increases the antibacterial activity of both TCPs against Gram-negative Escherichia coli by membrane disruption. Physiological salt level (150 mM NaCl) augments antibacterial activity of GKY25 but diminishes for the shorter HVF18. Replacing His with Leu or Ser in GKY25 abolishes the His protonation-dependent increase in antibacterial activity at pH 5.5, whereas substitution with Lys maintains activity at neutral (pH 7.4) and acidic pH. Interestingly, both TCPs display decreased binding affinities to human CD14 with decreasing pH, suggesting a likely switch in mode-of-action, from anti-inflammatory at neutral pH to antibacterial at acidic pH. Together, the results demonstrate that apart from structural prerequisites such as peptide length, charge, and hydrophobicity, the evolutionarily conserved His residue of TCPs influences their antibacterial effects and reveals a previously unknown aspect of TCPs biological action.

Details

Authors
Organisations
External organisations
  • Uppsala University
  • Nanyang Technological University
  • University of Copenhagen
  • Bispebjerg Hospital
  • A*Star, Bioinformatics Institute (BII)
  • National University of Singapore
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biochemistry and Molecular Biology
  • Dermatology and Venereal Diseases

Keywords

  • Antimicrobial peptides, Gram-negative bacteria, Host defense peptides, Lipopolysaccharide, pH, Thrombin
Original languageEnglish
Pages (from-to)2374-2384
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1860
Issue number11
Early online date2018 Jan 1
Publication statusPublished - 2018
Publication categoryResearch
Peer-reviewedYes