Investigating molecular recognition and biological function at interfaces using piscidins, antimicrobial peptides from fish |
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Authors: | Eduard Y. Chekmenev Kristen T. Forseth McKenna N. Manion Shiela M. Jones RaeLynn M. Endicott Lorraine M. Homem Jing He Peter L. Gor'kov Dan J. Mitchell Mary J. Ellard-Ivey Myriam Cotten |
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Affiliation: | a National High Magnetic Field Laboratory, Center for Interdisciplinary Magnetic Resonance, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310, USA b Department of Chemistry, Pacific Lutheran University, 1010 122d Street South, Tacoma, WA 98447, USA c Department of Biology, Pacific Lutheran University, 1010 122d Street South, Tacoma, WA 98447, USA d Department of Biomedical Sciences, College of Osteopathic Medicine, and Department of Chemistry and Biochemistry, College of Arts and Sciences, Ohio University, Athens, OH 45701, USA e Department of Biochemistry and Biophysics, Washington State University, Pullman, Washington 99163-4660, USA |
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Abstract: | We studied amidated and non-amidated piscidins 1 and 3, amphipathic cationic antimicrobial peptides from fish, to characterize functional and structural similarities and differences between these peptides and better understand the structural motifs involved in biological activity and functional diversity among amidated and non-amidated isoforms. Antimicrobial and hemolytic assays were carried out to assess their potency and toxicity, respectively. Site-specific high-resolution solid-state NMR orientational restraints were obtained from 15N-labeled amidated and non-amidated piscidins 1 and 3 in the presence of hydrated oriented lipid bilayers. Solid-state NMR and circular dichroism results indicate that the peptides are α-helical and oriented parallel to the membrane surface. This orientation was expected since peptide-lipid interactions are enhanced at the water-bilayer interface for amphipathic cationic antimicrobial peptides. 15N solid-state NMR performed on oriented samples demonstrate that piscidin experiences fast, large amplitude backbone motions around an axis parallel to the bilayer normal. Under the conditions tested here, piscidin 1 was confirmed to be more antimicrobially potent than piscidin 3 and antimicrobial activity was not affected by amidation. In light of functional and structural similarities between piscidins 1 and 3, we propose that their topology and fast dynamics are related to their mechanism of action. |
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Keywords: | ACAPs, antimicrobial, cationic, amphipathic peptides CD, circular dichroism DPG, diphosphatidylglycerate DMPC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine DMPG, 1,2-dimyristoyl-sn-glycero-3-phosphoglycerate DTPC, 1,2-O-ditetradecyl-sn-glycero-3-phosphocholine DTPG, 1,2-O-ditetradecyl-sn-glycero-3-phosphoglycerate HPLC, high performance liquid chromatography LPS:, lipopolysaccharides LUVs, large unilamellar vesicles MIC, minimal inhibitory concentration NMR, nuclear magnetic resonance p1(or 3)-COO&minus , non-amidated piscidin 1 (or 3) p1(or 3)-NH2, amidated piscidin 1 (or 3) PC, phosphatidylcholine PDB, protein data bank PE, phosphatidylethanolamine PISEMA, Polarization Inversion Spin Exchange at the Magic Angle PG, phosphatidylglycerol POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine POPG, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerate REDOR, Rotational Echo DOuble Resonance TFE, trifluoroethanol UV, ultraviolet |
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