Activity and characterization of a pH-sensitive antimicrobial peptide
| Autor: | Katharine E. Tarnawsky, Luis E. Santiago-Ortiz, Timothy D. Vaden, Gregory A. Caputo, Matthew R. Necelis, Thaddeus J. Palmer, Morgan A. Hitchner, David J. Shirley |
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| Rok vydání: | 2019 |
| Předmět: |
Cell Membrane Permeability
Lipid Bilayers Antimicrobial peptides Biophysics Peptide Biochemistry Article Structure-Activity Relationship 03 medical and health sciences Anti-Infective Agents Side chain Histidine Amino Acid Sequence 030304 developmental biology chemistry.chemical_classification 0303 health sciences Quenching (fluorescence) 030306 microbiology Chemistry Vesicle Cell Membrane Phosphatidylglycerols Cell Biology Hydrogen-Ion Concentration Fluorescence Anti-Bacterial Agents Membrane Phosphatidylcholines Peptides Antimicrobial Cationic Peptides |
| Zdroj: | Biochim Biophys Acta Biomembr |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/j.bbamem.2019.05.006 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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