title: Amphipathic polymers: tools to fold integral membrane proteins to their active form.
abstract: Among the major obstacles to pharmacological and structural studies of integral membrane proteins (MPs) are their natural scarcity and the difficulty in overproducing them in their native form. MPs can be overexpressed in the non-native state as inclusion bodies, but inducing them to achieve their functional three-dimensional structure has proven to be a major challenge. We describe here the use of an amphipathic polymer, amphipol A8-35, as a novel environment that allows both beta-barrel and alpha-helical MPs to fold to their native state, in the absence of detergents or lipids. Amphipols, which are extremely mild surfactants, appear to favor the formation of native intramolecular protein-protein interactions over intermolecular or protein-surfactant ones. The feasibility of the approach is demonstrated using as models OmpA and FomA, two outer membrane proteins from the eubacteria Escherichia coli and Fusobacterium nucleatum, respectively, and bacteriorhodopsin, a light-driven proton pump from the plasma membrane of the archaebacterium Halobacterium salinarium.
authors.affiliation: Fachbereich Biologie, Fach M 694, Universität Konstanz, D-78457 Konstanz, Germany.
authors.forename: Cosmin L
authors.initials: CL
authors.lastname: Pocanschi
authors.forename: Tassadite
authors.initials: T
authors.lastname: Dahmane
authors.forename: Yann
authors.initials: Y
authors.lastname: Gohon
authors.forename: Fabrice
authors.initials: F
authors.lastname: Rappaport
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Apell
authors.forename: Jörg H
authors.initials: JH
authors.lastname: Kleinschmidt
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Popot
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D001436:Bacteriorhodopsins / Q000737:chemistry*; D002942:Circular Dichroism; D029968:Escherichia coli Proteins / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D017510:Protein Folding; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C083760:fomA protein, Fusobacterium; C078167:OMPA outer membrane proteins; D001436:Bacteriorhodopsins