Membrane stiffness is modified by integral membrane proteins

The ease with which a cell membrane can bend and deform is important for a wide range of biological functions. Peripheral proteins that induce curvature in membranes (e.g. BAR domains) have been studied for a number of years. Little is known, however, about the effect of integral membrane proteins o...

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Main Authors: Sansom, M, Fowler, P, Helie, J, Duncan, A, Chavent, M, Koldsø, H
Format: Journal article
Published: Royal Society of Chemistry 2016
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author Sansom, M
Fowler, P
Helie, J
Duncan, A
Chavent, M
Koldsø, H
author_facet Sansom, M
Fowler, P
Helie, J
Duncan, A
Chavent, M
Koldsø, H
author_sort Sansom, M
collection OXFORD
description The ease with which a cell membrane can bend and deform is important for a wide range of biological functions. Peripheral proteins that induce curvature in membranes (e.g. BAR domains) have been studied for a number of years. Little is known, however, about the effect of integral membrane proteins on the stiffness of a membrane (characterised by the bending rigidity, Kc). We demonstrate by computer simulation that adding integral membrane proteins at physiological densities alters the stiffness of the membrane. First we establish that the coarse-grained MARTINI forcefield is able to accurately reproduce the bending rigidity of a small patch of 1,500 phosphatidyl choline lipids by comparing the calculated value to both experiment and an atomistic simulation of the same system. This enables us to simulate the dynamics of large (ca. 50,000 lipids) patches of membrane using the MARTINI coarse-grained description. We find that altering the lipid composition changes the bending rigidity. Adding integral membrane proteins to lipid bilayers also changes the bending rigidity, whilst adding a simple peripheral membrane protein has no effect. Our results suggest that integral membrane proteins can have different effects, and in the case of the bacterial outer membrane protein, BtuB, the greater the density of protein, the larger the reduction in stiffness.
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spelling oxford-uuid:4c34913d-53bc-4f1a-a1c8-18977b48a3472022-03-26T15:48:07ZMembrane stiffness is modified by integral membrane proteinsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:4c34913d-53bc-4f1a-a1c8-18977b48a347Symplectic Elements at OxfordRoyal Society of Chemistry2016Sansom, MFowler, PHelie, JDuncan, AChavent, MKoldsø, HThe ease with which a cell membrane can bend and deform is important for a wide range of biological functions. Peripheral proteins that induce curvature in membranes (e.g. BAR domains) have been studied for a number of years. Little is known, however, about the effect of integral membrane proteins on the stiffness of a membrane (characterised by the bending rigidity, Kc). We demonstrate by computer simulation that adding integral membrane proteins at physiological densities alters the stiffness of the membrane. First we establish that the coarse-grained MARTINI forcefield is able to accurately reproduce the bending rigidity of a small patch of 1,500 phosphatidyl choline lipids by comparing the calculated value to both experiment and an atomistic simulation of the same system. This enables us to simulate the dynamics of large (ca. 50,000 lipids) patches of membrane using the MARTINI coarse-grained description. We find that altering the lipid composition changes the bending rigidity. Adding integral membrane proteins to lipid bilayers also changes the bending rigidity, whilst adding a simple peripheral membrane protein has no effect. Our results suggest that integral membrane proteins can have different effects, and in the case of the bacterial outer membrane protein, BtuB, the greater the density of protein, the larger the reduction in stiffness.
spellingShingle Sansom, M
Fowler, P
Helie, J
Duncan, A
Chavent, M
Koldsø, H
Membrane stiffness is modified by integral membrane proteins
title Membrane stiffness is modified by integral membrane proteins
title_full Membrane stiffness is modified by integral membrane proteins
title_fullStr Membrane stiffness is modified by integral membrane proteins
title_full_unstemmed Membrane stiffness is modified by integral membrane proteins
title_short Membrane stiffness is modified by integral membrane proteins
title_sort membrane stiffness is modified by integral membrane proteins
work_keys_str_mv AT sansomm membranestiffnessismodifiedbyintegralmembraneproteins
AT fowlerp membranestiffnessismodifiedbyintegralmembraneproteins
AT heliej membranestiffnessismodifiedbyintegralmembraneproteins
AT duncana membranestiffnessismodifiedbyintegralmembraneproteins
AT chaventm membranestiffnessismodifiedbyintegralmembraneproteins
AT koldsøh membranestiffnessismodifiedbyintegralmembraneproteins