title: Pre-transition effects mediate forces of assembly between transmembrane proteins.
abstract: We present a mechanism for a generic, powerful force of assembly and mobility for transmembrane proteins in lipid bilayers. This force is a pre-transition (or pre-melting) effect for the first-order transition between ordered and disordered phases in the membrane. Using large-scale molecular simulation, we show that a protein with hydrophobic thickness equal to that of the disordered phase embedded in an ordered bilayer stabilizes a microscopic order-disorder interface. The stiffness of that interface is finite. When two such proteins approach each other, they assemble because assembly reduces the net interfacial energy. Analogous to the hydrophobic effect, we refer to this phenomenon as the 'orderphobic effect'. The effect is mediated by proximity to the order-disorder phase transition and the size and hydrophobic mismatch of the protein. The strength and range of forces arising from this effect are significantly larger than those that could arise from membrane elasticity for the membranes considered.
authors.affiliation: Department of Chemistry, University of California, Berkeley, Berkeley, United States.
authors.forename: Shachi
authors.initials: S
authors.lastname: Katira
authors.affiliation: Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States.|Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, United States.
authors.forename: Kranthi K
authors.initials: KK
authors.lastname: Mandadapu
authors.affiliation: Department of Chemistry, University of Chicago, Chicago, United States.
authors.forename: Suriyanarayanan
authors.initials: S
authors.lastname: Vaikuntanathan
authors.affiliation: Department of Chemistry, University of California, Berkeley, Berkeley, United States.|Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, United States.|Laboratory of Molecular Simulation, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, Sion, Switzerland.
authors.forename: Berend
authors.initials: B
authors.lastname: Smit
authors.affiliation: Department of Chemistry, University of California, Berkeley, Berkeley, United States.
authors.forename: David
authors.initials: D
authors.lastname: Chandler
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D055503:Protein Multimerization
chemical_list: D008051:Lipid Bilayers; D008565:Membrane Proteins
keywords: biophysics; hydrophobic mismatch; lipid bilayers; none; orderphobe; orderphobic effect; phase transition; structural biology