title: Rigid proteins and softening of biological membranes-with application to HIV-induced cell membrane softening.
abstract: A key step in the HIV-infection process is the fusion of the virion membrane with the target cell membrane and the concomitant transfer of the viral RNA. Experimental evidence suggests that the fusion is preceded by considerable elastic softening of the cell membranes due to the insertion of fusion peptide in the membrane. What are the mechanisms underpinning the elastic softening of the membrane upon peptide insertion? A broader question may be posed: insertion of rigid proteins in soft membranes ought to stiffen the membranes not soften them. However, experimental observations perplexingly appear to show that rigid proteins may either soften or harden membranes even though conventional wisdom only suggests stiffening. In this work, we argue that regarding proteins as merely non-specific rigid inclusions is flawed, and each protein has a unique mechanical signature dictated by its specific interfacial coupling to the surrounding membrane. Predicated on this hypothesis, we have carried out atomistic simulations to investigate peptide-membrane interactions. Together with a continuum model, we reconcile contrasting experimental data in the literature including the case of HIV-fusion peptide induced softening. We conclude that the structural rearrangements of the lipids around the inclusions cause the softening or stiffening of the biological membranes.
authors.affiliation: Department of Mechanical Engineering, University of Houston, Houston TX, USA.
authors.forename: Himani
authors.initials: H
authors.lastname: Agrawal
authors.affiliation: Department of Mechanical Engineering, University of Houston, Houston TX, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Zelisko
authors.affiliation: Department of Mathematics and Department of Mechanical Aerospace Engineering, Rutgers University, New Brunswick NJ, USA.
authors.forename: Liping
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering, University of Houston, Houston TX, USA.|Department of Physics, University of Houston, Houston TX, USA.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Sharma
mesh_terms: D002462:Cell Membrane / Q000737:chemistry* / Q000821:virology*; D055598:Chemical Phenomena; D003198:Computer Simulation; D006678:HIV / Q000502:physiology*; D054298:Human Immunodeficiency Virus Proteins / Q000737:chemistry* / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D054298:Human Immunodeficiency Virus Proteins