The long-term objective of this research is the development of rational methods for the design and improvement of membrane-penetrating, amphipathic peptides that are antibiotic or cytolytic, or can carry other toxic molecules as cargo into cells. Critical knowledge in reaching this objective is the determination of the mechanism(s) of membrane penetration by these peptides. An important step in obtaining this information is the proposal in this application of an experimental kinetic study, combined with a global theoretical analysis that we have developed, of membrane penetration by a set of known cytotoxic or antibacterial amphipathic peptides. Peptides in this class are known to exhibit considerable target specificity which appears to derive from the interaction of the peptides with the lipid bilayer of the target cell membrane without the intervention of protein receptors. The mechanism of this widespread biological defense system is presently not understood. Four peptides that differ in length (from 14 to 37 amino acids), charge (0 to +6), and specificity (antibiotic, antifungal, or hemolytic), were selected to test a set of current models of peptide mechanisms. In addition, the chimeric construct transportan TP10 will also be examined in order to determine its mechanism and usefulness as a drug delivery vehicle. Transportans have been shown to be able to transport even large proteins, such as green fluorescent protein, into cells. It will be determined whether and how attachment of cargo modifies the mechanism of the peptide action. In order to be useful as vehicles to transport cargo into cells, peptides must translocate into the interior of vesicles without getting permanently inserted into the bilayer. This study will indicate which of the types of peptides examined is the best template to build such a peptide vehicle. Cargo-carrying peptides can be used to transport drugs into eukaryotic cells or antibiotics into bacterial cells. Surmounting cellular barriers, including intracellular compartments, is a major difficulty in the use of antibiotics.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Academic Research Enhancement Awards (AREA) (R15)
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Biophysical Chemistry Study Section (BBCB)
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Chin, Jean
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University of North Carolina Wilmington
Schools of Arts and Sciences
United States
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Kreutzberger, Mark A; Pokorny, Antje; Almeida, Paulo F (2017) Daptomycin-Phosphatidylglycerol Domains in Lipid Membranes. Langmuir 33:13669-13679
King, Mariah J; Bennett, Ashley L; Almeida, Paulo F et al. (2016) Coarse-grained simulations of hemolytic peptide ?-lysin interacting with a POPC bilayer. Biochim Biophys Acta 1858:3182-3194
Ablan, Francis D O; Spaller, B Logan; Abdo, Kaitlyn I et al. (2016) Charge Distribution Fine-Tunes the Translocation of ?-Helical Amphipathic Peptides across Membranes. Biophys J 111:1738-1749
Kreutzberger, Mark A; Tejada, Emmanuel; Wang, Ying et al. (2015) GUVs melt like LUVs: the large heat capacity of MLVs is not due to large size or small curvature. Biophys J 108:2619-22
Cherry, Melissa A; Higgins, Sarah K; Melroy, Hilary et al. (2014) Peptides with the same composition, hydrophobicity, and hydrophobic moment bind to phospholipid bilayers with different affinities. J Phys Chem B 118:12462-70
Almeida, Paulo F (2014) Membrane-active peptides: binding, translocation, and flux in lipid vesicles. Biochim Biophys Acta 1838:2216-27
Wheaten, Sterling A; Lakshmanan, Aruna; Almeida, Paulo F (2013) Statistical analysis of peptide-induced graded and all-or-none fluxes in giant vesicles. Biophys J 105:432-43
Wheaten, Sterling A; Ablan, Francis D O; Spaller, B Logan et al. (2013) Translocation of cationic amphipathic peptides across the membranes of pure phospholipid giant vesicles. J Am Chem Soc 135:16517-25
Spaller, B Logan; Trieu, Julie M; Almeida, Paulo F (2013) Hemolytic activity of membrane-active peptides correlates with the thermodynamics of binding to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers. J Membr Biol 246:257-62
Almeida, Paulo F; Ladokhin, Alexey S; White, Stephen H (2012) Hydrogen-bond energetics drive helix formation in membrane interfaces. Biochim Biophys Acta 1818:178-82

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