Spring Constants for Channel-Induced Lipid Bilayer Deformations Estimates Using Gramicidin Channels
Open Access
- 1 February 1999
- journal article
- Published by Elsevier BV in Biophysical Journal
- Vol. 76 (2), 889-895
- https://doi.org/10.1016/s0006-3495(99)77252-8
Abstract
Hydrophobic interactions between a bilayer and its embedded membrane proteins couple protein conformational changes to changes in the packing of the surrounding lipids. The energetic cost of a protein conformational change therefore includes a contribution from the associated bilayer deformation energy (DeltaGdef0), which provides a mechanism for how membrane protein function depends on the bilayer material properties. Theoretical studies based on an elastic liquid-crystal model of the bilayer deformation show that DeltaGdef0 should be quantifiable by a phenomenological linear spring model, in which the bilayer mechanical characteristics are lumped into a single spring constant. The spring constant scales with the protein radius, meaning that one can use suitable reporter proteins for in situ measurements of the spring constant and thereby evaluate quantitatively the DeltaGdef0 associated with protein conformational changes. Gramicidin channels can be used as such reporter proteins because the channels form by the transmembrane assembly of two nonconducting monomers. The monomerleft arrow over right arrow dimer reaction thus constitutes a well characterized conformational transition, and it should be possible to determine the phenomenological spring constant describing the channel-induced bilayer deformation by examining how DeltaGdef0 varies as a function of a mismatch between the hydrophobic channel length and the unperturbed bilayer thickness. We show this is possible by analyzing experimental studies on the relation between bilayer thickness and gramicidin channel duration. The spring constant in nominally hydrocarbon-free bilayers agrees well with estimates based on a continuum analysis of inclusion-induced bilayer deformations using independently measured material constants.Keywords
This publication has 48 references indexed in Scilit:
- Gramicidin Channel Function Does Not Depend on Phospholipid ChiralityBiochemistry, 1995
- Insulin Receptor Autophosphorylation and Signaling is Altered by Modulation of Membrane Physical PropertiesBiochemistry, 1995
- The curvature elastic-energy function of the lipid–water cubic mesophaseNature, 1994
- Energetics of Heterodimer Formation among Gramicidin Analogues with an NH2-terminal Addition or Deletion: Consequences of Missing a Residue at the Join in the ChannelJournal of Molecular Biology, 1993
- Arrangement of the acetylcholine receptor subunits in the resting and desensitized states, determined by cryoelectron microscopy of crystallized Torpedo postsynaptic membranes.The Journal of cell biology, 1988
- Specificity of lipid-protein interactions as determined by spectroscopic techniquesBiochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, 1985
- Lyotropic effects of alkanes and headgroup composition on the lα -Hii lipid liquid crystal phase transition : hydrocarbon packing versus intrinsic curvatureJournal de Physique, 1985
- The effect of bilayer thickness on the activity of (Na+ + K+)-ATPaseBiochimica et Biophysica Acta (BBA) - Biomembranes, 1981
- Influence of membrane thickness and ion concentration on the properties of the gramicidin A channel Autocorrelation, spectral power density, relaxation and single-channel studiesBiochimica et Biophysica Acta (BBA) - Biomembranes, 1977
- Gramicidin A. V. The Structure of Valine- and Isoleucine-gramicidin AJournal of the American Chemical Society, 1965