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 drug molecules as cargo into cells. Critical knowledge in reaching this objective is the determination of the mechanism of membrane penetration by these peptides. Antimicrobial peptides 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. Furthermore, the development of resistance by bacteria is much more difficult because it entails massive changes in the bacterial membranes. Cell-penetrating peptides (CPPs) have been shown to deliver drugs or nucleic acids into cells and their potential for the treatment of cancer is enormous. Polycationic CPPs appear to enter the cell via endocytosis;but how they leave the endosome remains poorly understood. Amphipathic CPPs are similar to antimicrobial peptides. They appear to cross the lipid bilayer, either the plasma membrane or the endosomal membrane, without the need for external energy. Our challenge, regarding both classes of peptides, is to understand the mechanism of translocation. Two main hypotheses concerning the mechanism of membrane permeation by these peptides are proposed and will be tested. To do that, a new set of assays to assess membrane translocation by these peptides has been designed. The prediction is that specific features of the peptide sequences are necessary for peptides to penetrate cells or disrupt the membrane. Surmounting cellular barriers, including intracellular compartments, is a major difficulty in the use of antibiotics, in drug delivery, and in molecular therapy. This proposal addresses one of the fundamental difficulties involves: the mechanism of membrane permeation.

Public Health Relevance

This project seeks to establish principles for rational design of antibiotic and cell- penetrating peptides. Understanding how the primary structures of these peptides determine their ability to cross the lipid bilayer barrier of cell membranes is of paramount importance for the development of new antibiotics and molecular vehicles for targetted delivery of drugs or therapeutical agents into specific cells. Targetted delivery has vast potential clinical applications, for example in the treatment of cancer.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Academic Research Enhancement Awards (AREA) (R15)
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Biochemistry and Biophysics of Membranes Study Section (BBM)
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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
Almeida, Paulo F (2014) Membrane-active peptides: binding, translocation, and flux in lipid vesicles. Biochim Biophys Acta 1838:2216-27
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
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
Wood, Mona L; Schow, Eric V; Freites, J Alfredo et al. (2012) Water wires in atomistic models of the Hv1 proton channel. Biochim Biophys Acta 1818:286-93

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