Effect of diaminopropionic acid (Dap) on the biophysical properties of a modified synthetic channel-forming peptide

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dc.contributor.author Bukovnik, Urska
dc.contributor.author Sala-Rabanal, Monica
dc.contributor.author Francis, Simonne
dc.contributor.author Frazier, Shawnalea J.
dc.contributor.author Schultz, Bruce D.
dc.contributor.author Nichols, Colin G.
dc.contributor.author Tomich, John M.
dc.date.accessioned 2014-12-04T14:00:56Z
dc.date.available 2014-12-04T14:00:56Z
dc.date.issued 2014-12-04
dc.identifier.uri http://hdl.handle.net/2097/18793
dc.description.abstract Channel replacement therapy, based on synthetic channel-forming peptides (CFPs) with the ability to supersede defective endogenous ion channels, is a novel treatment modality that may augment existing interventions against multiple diseases. Previously, we derived CFPs from the second transmembrane segment of the α-subunit of the glycine receptor, M2GlyR, which forms chloride-selective channels in its native form. The best candidate, NK₄-M2GlyR T19R, S22W (p22-T19R, S22W), was water-soluble, incorporated into cell membranes and was nonimmunogenic, but lacked the structural properties for high conductance and anion selectivity when assembled into a pore. Further studies suggested that the threonine residues at positions 13, 17, and 20 line the pore of assembled p22-T19R, S22W, and here we used 2,3-diaminopropionic acid (Dap) substitutions to introduce positive charges to the pore-lining interface of the predicted p22-T19R, S22W channel. Dap-substituted p22-T19R, S22W peptides retained the α-helical secondary structure characteristic of their parent peptide, and induced short-circuit transepithelial currents when exposed to the apical membrane of Madin-Darby canine kidney (MDCK) cells; the sequences containing multiple Dap-substituted residues induced larger currents than the peptides with single or no Dap substitutions. To gain further insights into the effects of Dap residues on the properties of the putative pore, we performed two-electrode voltage clamp electrophysiology on Xenopus oocytes exposed to p22-T19R, S22W or its Dap-modified analogues. We observed that Dap-substituted peptides also induced significantly larger voltage-dependent currents than the parent compound, but there was no apparent change in reversal potential upon replacement of external Na⁺, Cl⁻ or K⁺, indicating that these currents remained nonselective. These results suggest that the introduction of positively charged side chains in predicted pore-lining residues does not improve anion-to-cation selectivity, but results in higher conductance, perhaps due to higher oligomerization numbers. en_US
dc.language.iso en_US en_US
dc.relation.uri http://pubs.acs.org/doi/abs/10.1021/mp4002377 en_US
dc.rights This document is the Accepted Manuscript version of a Published Work that appeared in final form in Molecular Pharmaceutics, copyright (c) American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/mp4002377. en_US
dc.subject Channel-forming peptide en_US
dc.subject Ion selectivity en_US
dc.subject Anion channel en_US
dc.subject Chloride channel en_US
dc.subject Diaminopropionic acid en_US
dc.subject Dap en_US
dc.subject Channel replacement therapy en_US
dc.subject Cystic fibrosis en_US
dc.title Effect of diaminopropionic acid (Dap) on the biophysical properties of a modified synthetic channel-forming peptide en_US
dc.type Article (author version) en_US
dc.date.published 2013 en_US
dc.citation.doi 10.1021/mp4002377 en_US
dc.citation.epage 3966 en_US
dc.citation.issue 10 en_US
dc.citation.jtitle Molecular Pharmaceutics en_US
dc.citation.spage 3959 en_US
dc.citation.volume 10 en_US
dc.contributor.authoreid bschultz en_US
dc.contributor.authoreid jtomich en_US

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