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Wiedman Hristova

Jing He, Lilia I Melnik, Alexander Komin, Gregory Wiedman, Taylor Fuselier, Cameron F Morris, Charles G Starr, Peter C Searson, William R Gallaher, Kalina Hristova, Robert F Garry, William C Wimley
The Ebola virus (EBOV) genome encodes for a partly conserved, 40-residue, nonstructural polypeptide, called the delta peptide, which is produced in abundance during Ebola virus disease. The function of the delta peptide is unknown, but sequence analysis has suggested that delta peptide could be a viroporin, belonging to a diverse family of membrane-permeabilizing small polypeptides involved in replication and pathogenesis of numerous viruses. Full length and conserved C-terminal delta peptide fragments permeabilize the plasma membranes of nucleated cells of rodent, dog, monkey and human origin, increase ion permeability across confluent cell monolayers and permeabilize synthetic lipid bilayers...
May 24, 2017: Journal of Virology
Gregory Wiedman, Sarah Y Kim, Elmer Zapata-Mercado, William C Wimley, Kalina Hristova
pH-triggered membrane-permeabilizing peptides could be exploited in a variety of applications, such as to enable cargo release from endosomes for cellular delivery, or as cancer therapeutics that selectively permeabilize the plasma membranes of malignant cells. Such peptides would be especially useful if they could enable the movement of macromolecules across membranes, a rare property in membrane-permeabilizing peptides. Here we approach this goal by using an orthogonal high-throughput screen of an iterative peptide library to identify peptide sequences that have the following two properties: (i) little synthetic lipid membrane permeabilization at physiological pH 7 at high peptide concentration and (ii) efficient formation of macromolecule-sized defects in synthetic lipid membranes at acidic pH 5 and low peptide concentration...
January 18, 2017: Journal of the American Chemical Society
Gregory Wiedman, William C Wimley, Kalina Hristova
In this work, we sought to rationally design membrane-active peptides that are triggered by low pH to form macromolecular-sized pores in lipid bilayers. Such peptides could have broad utility in biotechnology and in nanomedicine as cancer therapeutics or drug delivery vehicles that promote release of macromolecules from endosomes. Our approach to rational design was to combine the properties of a pH-independent peptide, MelP5, which forms large pores allowing passage of macromolecules, with the properties of two pH-dependent membrane-active peptides, pHlip and GALA...
April 2015: Biochimica et Biophysica Acta
Charles H Chen, Gregory Wiedman, Ayesha Khan, Martin B Ulmschneider
Unbiased molecular simulation is a powerful tool to study the atomic details driving functional structural changes or folding pathways of highly fluid systems, which present great challenges experimentally. Here we apply unbiased long-timescale molecular dynamics simulation to study the ab initio folding and partitioning of melittin, a template amphiphilic membrane active peptide. The simulations reveal that the peptide binds strongly to the lipid bilayer in an unstructured configuration. Interfacial folding results in a localized bilayer deformation...
September 2014: Biochimica et Biophysica Acta
Gregory Wiedman, Taylor Fuselier, Jing He, Peter C Searson, Kalina Hristova, William C Wimley
Peptides that self-assemble, at low concentration, into bilayer-spanning pores which allow the passage of macromolecules would be beneficial in multiple areas of biotechnology. However, there are few, if any, natural or designed peptides that have this property. Here we show that the 26-residue peptide "MelP5", a synthetically evolved gain-of-function variant of the bee venom lytic peptide melittin identified in a high-throughput screen for small molecule leakage, enables the passage of macromolecules across bilayers under conditions where melittin and other pore-forming peptides do not...
March 26, 2014: Journal of the American Chemical Society
Juan Cruz, Mihaela Mihailescu, Greg Wiedman, Katherine Herman, Peter C Searson, William C Wimley, Kalina Hristova
Using a high throughput screen, we have identified a family of 12-residue long peptides that spontaneously translocate across membranes. These peptides function by a poorly understood mechanism that is very different from that of the well-known, highly cationic cell penetrating peptides such as the tat peptide from HIV. The newly discovered translocating peptides can carry polar cargoes across synthetic bilayers and across cellular membranes quickly and spontaneously without disrupting the membrane. Here we report on the biophysical characterization of a representative translocating peptide from the selected family, TP2, as well as a negative control peptide, ONEG, from the same library...
June 4, 2013: Biophysical Journal
Gregory Wiedman, Katherine Herman, Peter Searson, William C Wimley, Kalina Hristova
Melittin is a 26-residue bee venom peptide that folds into amphipathic α-helix and causes membrane permeabilization via a mechanism that is still disputed. While an equilibrium transmembrane pore model has been a central part of the mechanistic dialogue for decades, there is growing evidence that a transmembrane pore is not required for melittin's activity. In part, the controversy is due to limited experimental tools to probe the bilayer's response to melittin. Electrochemical impedance spectroscopy (EIS) is a technique that can reveal details of molecular mechanism of peptide activity, as it yields direct, real-time measurements of membrane resistance and capacitance of supported bilayers...
May 2013: Biochimica et Biophysica Acta
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