Activity and characterization of a pH-sensitive antimicrobial peptide

Morgan A. Hitchner, Luis E. Santiago-Ortiz, Matthew R. Necelis, David J. Shirley, Thaddeus J. Palmer, Katharine E. Tarnawsky, Timothy Vaden, Gregory Caputo

Research output: Contribution to journalArticle

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Abstract

Antimicrobial peptides (AMPs) have been an area of great interest, due to the high selectivity of these molecules toward bacterial targets over host cells and the limited development of bacterial resistance to these molecules throughout evolution. Previous work showed that when Histidine was incorporated into the peptide C18G it lost antimicrobial activity. The role of pH on activity and biophysical properties of the peptide was investigated to explain this phenomenon. Minimal inhibitory concentration (MIC) results demonstrated that decreased media pH increased antimicrobial activity. Trichloroethanol (TCE) quenching and red-edge excitation spectroscopy (REES) showed a clear pH dependence on peptide aggregation in solution. Trp fluorescence was used to monitor binding to lipid vesicles and demonstrated the peptide binds to anionic bilayers at all pH values tested, however, binding to zwitterionic bilayers was enhanced at pH 7 and 8 (above the His pKa). Dual Quencher Analysis (DQA) confirmed the peptide inserted more deeply in PC:PG and PE:PG membranes, but could insert into PC bilayers at pH conditions above the His pKa. Bacterial membrane permeabilization assays which showed enhanced membrane permeabilization at pH 5 and 6 but vesicle leakage assays indicate enhanced permeabilization of PC and PC:PG bilayers at neutral pH. The results indicate the ionization of the His side chain affects the aggregation state of the peptide in solution and the conformation the peptide adopts when bound to bilayers, but there are likely more subtle influences of lipid composition and properties that impact the ability of the peptide to form pores in membranes.

Original languageEnglish (US)
Article number182984
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1861
Issue number10
DOIs
StatePublished - Oct 1 2019

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Peptides
Membranes
Assays
Agglomeration
Lipids
Molecules
Die casting inserts
Histidine
Ionization
Conformations
Quenching
Spectrum Analysis
Fluorescence
Spectroscopy
Chemical analysis

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Cell Biology

Cite this

Hitchner, M. A., Santiago-Ortiz, L. E., Necelis, M. R., Shirley, D. J., Palmer, T. J., Tarnawsky, K. E., ... Caputo, G. (2019). Activity and characterization of a pH-sensitive antimicrobial peptide. Biochimica et Biophysica Acta - Biomembranes, 1861(10), [182984]. https://doi.org/10.1016/j.bbamem.2019.05.006
Hitchner, Morgan A. ; Santiago-Ortiz, Luis E. ; Necelis, Matthew R. ; Shirley, David J. ; Palmer, Thaddeus J. ; Tarnawsky, Katharine E. ; Vaden, Timothy ; Caputo, Gregory. / Activity and characterization of a pH-sensitive antimicrobial peptide. In: Biochimica et Biophysica Acta - Biomembranes. 2019 ; Vol. 1861, No. 10.
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Hitchner, MA, Santiago-Ortiz, LE, Necelis, MR, Shirley, DJ, Palmer, TJ, Tarnawsky, KE, Vaden, T & Caputo, G 2019, 'Activity and characterization of a pH-sensitive antimicrobial peptide', Biochimica et Biophysica Acta - Biomembranes, vol. 1861, no. 10, 182984. https://doi.org/10.1016/j.bbamem.2019.05.006

Activity and characterization of a pH-sensitive antimicrobial peptide. / Hitchner, Morgan A.; Santiago-Ortiz, Luis E.; Necelis, Matthew R.; Shirley, David J.; Palmer, Thaddeus J.; Tarnawsky, Katharine E.; Vaden, Timothy; Caputo, Gregory.

In: Biochimica et Biophysica Acta - Biomembranes, Vol. 1861, No. 10, 182984, 01.10.2019.

Research output: Contribution to journalArticle

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AU - Hitchner, Morgan A.

AU - Santiago-Ortiz, Luis E.

AU - Necelis, Matthew R.

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Hitchner MA, Santiago-Ortiz LE, Necelis MR, Shirley DJ, Palmer TJ, Tarnawsky KE et al. Activity and characterization of a pH-sensitive antimicrobial peptide. Biochimica et Biophysica Acta - Biomembranes. 2019 Oct 1;1861(10). 182984. https://doi.org/10.1016/j.bbamem.2019.05.006