Peptide antibiotic trichogin in model membranes: Self-association and capture of fatty acids |
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Authors: | Ekaterina F. Afanasyeva Victoria N. Syryamina Marta De Zotti Fernando Formaggio Claudio Toniolo Sergei A. Dzuba |
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Affiliation: | 1. Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation;2. Novosibirsk State University, Novosibirsk 630090, Russian Federation;3. Department of Chemical Sciences, University of Padova, 35131 Padova, Italy;4. Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy |
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Abstract: | The antimicrobial action of peptides in bacterial membranes is commonly related to their mode of self-assembling which results in pore formation. To optimize peptide antibiotic use for therapeutic purposes, a study on the concentration dependence of self-assembling process is thus desirable. In this work, we investigate this dependence for peptaibol trichogin GA IV (Tric) in the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) model membrane in the range of peptide concentrations between 0.5 and 3.3?mol%. Pulsed double electron-electron resonance (PELDOR) applied on spin-labeled peptide analogs highlights the onset of peptide dimerization above a critical peptide concentration value, namely ~ 2?mol%. Electron spin echo (ESE) envelope modulation (ESEEM) for D2O-hydrated bilayers shows that dimerization is accompanied by peptide re-orientation towards a trans-membrane disposition. For spin-labeled stearic acids (5-DSA) in POPC bilayers, the study of ESE decays and ESEEM in the presence of a deuterated peptide analog indicates that above the critical peptide concentration the 5-DSA molecules are attracted by peptide molecules, forming nanoclusters. As the 5-DSA molecules represent a model for the behavior of fatty acids participating in bacterial membrane homeostasis, such capturing action by Tric may represent an additional mechanism of its antibiotic activity. |
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Keywords: | Dipolar spectroscopy ESEEM EPR Fatty acids Ion channels PELDOR Trichogin |
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