title: Low-resolution structures of OmpA⋅DDM protein-detergent complexes.
abstract: We have used SAXS to determine the low-resolution structure of the outer-membrane protein OmpA from E. coli solubilized by the surfactant dodecyl maltoside (DDM). We have studied three variants of the transmembrane domain of OmpA-namely monomers, self-associated dimers, and covalently linked dimers-as well as the monomeric species of the full-length protein with the periplasmic domain. We can successfully model the structures of the monomeric and covalently linked dimer as one and two natively folded proteins in a DDM micelle, respectively, whereas the noncovalently linked dimer presents a more complicated structure, possibly due to higher-order species. We have determined the structure of the full-length protein to be that of a globular periplasmic domain attached through a flexible linker to the transmembrane domain. This approach provides valuable information about how membrane proteins are embedded in amphiphilic environments.
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C (Denmark); Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C (Denmark).
authors.forename: Jørn
authors.initials: J
authors.lastname: Døvling Kaspersen
authors.forename: Christian
authors.initials: C
authors.lastname: Moestrup Jessen
authors.forename: Brian
authors.initials: B
authors.lastname: Stougaard Vad
authors.forename: Esben
authors.initials: E
authors.lastname: Skipper Sørensen
authors.forename: Kell
authors.initials: K
authors.lastname: Kleiner Andersen
authors.forename: Marianne
authors.initials: M
authors.lastname: Glasius
authors.forename: Cristiano Luis
authors.initials: CL
authors.lastname: Pinto Oliveira
authors.forename: Daniel Erik
authors.initials: DE
authors.lastname: Otzen
authors.forename: Jan Skov
authors.initials: JS
authors.lastname: Pedersen
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D003902:Detergents / Q000737:chemistry*; D019281:Dimerization; D004926:Escherichia coli / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry*; D008823:Micelles; D008958:Models, Molecular; D011487:Protein Conformation; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D012995:Solubility; D014961:X-Ray Diffraction
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003902:Detergents; D005960:Glucosides; D008823:Micelles; C078167:OMPA outer membrane proteins; C040358:dodecyl maltoside
keywords: membrane proteins; micelles; outer-membrane protein A; protein/detergent stoichiometry; small-angle X-ray scattering