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

Holdbrook, Daniel A.; Singh, Shalini; Choong, Yeu Khai; Petrlova, Jitka LU ; Malmsten, Martin; Bond, Peter J.; Verma, Navin Kumar; Schmidtchen, Artur LU and Saravanan, Rathi (2018) In Biochimica et Biophysica Acta - Biomembranes 1860(11). p.2374-2384
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... (More)

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.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Antimicrobial peptides, Gram-negative bacteria, Host defense peptides, Lipopolysaccharide, pH, Thrombin
in
Biochimica et Biophysica Acta - Biomembranes
volume
1860
issue
11
pages
2374 - 2384
publisher
Elsevier
external identifiers
  • scopus:85048928965
ISSN
0005-2736
DOI
10.1016/j.bbamem.2018.06.002
language
English
LU publication?
yes
id
51d41ce8-cb73-4798-995b-33fcdc7619a1
date added to LUP
2018-07-06 14:18:42
date last changed
2019-02-20 11:21:51
@article{51d41ce8-cb73-4798-995b-33fcdc7619a1,
  abstract     = {<p>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.</p>},
  author       = {Holdbrook, Daniel A. and Singh, Shalini and Choong, Yeu Khai and Petrlova, Jitka and Malmsten, Martin and Bond, Peter J. and Verma, Navin Kumar and Schmidtchen, Artur and Saravanan, Rathi},
  issn         = {0005-2736},
  keyword      = {Antimicrobial peptides,Gram-negative bacteria,Host defense peptides,Lipopolysaccharide,pH,Thrombin},
  language     = {eng},
  month        = {01},
  number       = {11},
  pages        = {2374--2384},
  publisher    = {Elsevier},
  series       = {Biochimica et Biophysica Acta - Biomembranes},
  title        = {Influence of pH on the activity of thrombin-derived antimicrobial peptides},
  url          = {http://dx.doi.org/10.1016/j.bbamem.2018.06.002},
  volume       = {1860},
  year         = {2018},
}