Biophysical Journal 2016-01-05

Cholesterol-Enriched Domain Formation Induced by Viral-Encoded, Membrane-Active Amphipathic Peptide.

Joshua M Hanson, Douglas L Gettel, Seyed R Tabaei, Joshua Jackman, Min Chul Kim, Darryl Y Sasaki, Jay T Groves, Bo Liedberg, Nam-Joon Cho, Atul N Parikh

Index: Biophys. J. 110 , 176-87, (2016)

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Abstract

The α-helical (AH) domain of the hepatitis C virus nonstructural protein NS5A, anchored at the cytoplasmic leaflet of the endoplasmic reticulum, plays a role in viral replication. However, the peptides derived from this domain also exhibit remarkably broad-spectrum virocidal activity, raising questions about their modes of membrane association. Here, using giant lipid vesicles, we show that the AH peptide discriminates between membrane compositions. In cholesterol-containing membranes, peptide binding induces microdomain formation. By contrast, cholesterol-depleted membranes undergo global softening at elevated peptide concentrations. Furthermore, in mixed populations, the presence of ∼100 nm vesicles of viral dimensions suppresses these peptide-induced perturbations in giant unilamellar vesicles, suggesting size-dependent membrane association. These synergistic composition- and size-dependent interactions explain, in part, how the AH domain might on the one hand segregate molecules needed for viral assembly and on the other hand furnish peptides that exhibit broad-spectrum virocidal activity. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.