title: Translational diffusion measurements by microcoil NMR in aqueous solutions of the Fos-10 detergent-solubilized membrane protein OmpX.
abstract: Aqueous solutions of the detergent Fos-10 (n-decylphosphocholine) without and with addition of the integral membrane protein (IMP) OmpX (outer membrane protein X) have been characterized using pulsed field gradient-stimulated echo (PFG-STE) NMR experiments for measurements of translational diffusion coefficients. Effective diffusion coefficients for Fos-10 micelles in the absence of OmpX were obtained by observation of NMR signals from 10-bromodecan-1-ol that had been inserted into the micelles, and in the presence of OmpX by NMR observation of the protein. It is thus shown that solutions of Fos-10-reconstituted OmpX can be quantitatively described as a mixture of Fos-10 monomers, uniform Fos-10 micelles, and uniform OmpX-containing Fos-10 micelles, with Fos-10 monomers in fast exchange between the pools of these three species. This result establishes an avenue for efficient determination of the effective translational diffusion coefficients of IMP-containing detergent micelles based on observation of the intense detergent NMR signals, which is also applicable with unlabeled IMPs. This monitoring of the species present in a given IMP solution contributes to improved guidelines for rational selection of detergent and buffer conditions in structural studies of integral membrane proteins.
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Reto
authors.initials: R
authors.lastname: Horst
authors.forename: Pawel
authors.initials: P
authors.lastname: Stanczak
authors.forename: Pedro
authors.initials: P
authors.lastname: Serrano
authors.forename: Kurt
authors.initials: K
authors.lastname: Wüthrich
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D003902:Detergents / Q000737:chemistry*; D004058:Diffusion; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006867:Hydrolases / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry; D012995:Solubility; D012996:Solutions; D014867:Water / Q000737:chemistry
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003902:Detergents; D029968:Escherichia coli Proteins; D012996:Solutions; D014867:Water; D010767:Phosphorylcholine; C482905:OmpX protein, E coli; C031167:N-decylphosphorylcholine; D006867:Hydrolases