title: Backbone structure of transmembrane domain IX of the Na+/proline transporter PutP of Escherichia coli.
abstract: The backbone structure is determined by site-directed spin labeling, double electron electron resonance measurements of distances, and modeling in terms of a helix-loop-helix construct for a transmembrane domain that is supposed to line the translocation pathway in the 54.3 kDa Na(+)/proline symporter PutP of Escherichia coli. The conformational distribution of the spin labels is accounted for by a rotamer library. An ensemble of backbone models with a root mean-square deviation of less than 2 A is obtained. These models exhibit a pronounced kink near residue T341, which is involved in substrate binding. The kink may be associated with a hinge that allows the protein to open and close an inwardly oriented cavity.
authors.affiliation: Department of Biology I, Microbiology, Ludwig-Maximilians-Universität Munich, Munich, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hilger
authors.forename: Yevhen
authors.initials: Y
authors.lastname: Polyhach
authors.forename: Heinrich
authors.initials: H
authors.lastname: Jung
authors.forename: Gunnar
authors.initials: G
authors.lastname: Jeschke
mesh_terms: D000595:Amino Acid Sequence; D026921:Amino Acid Transport Systems, Neutral / Q000737:chemistry* / Q000235:genetics; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D008956:Models, Chemical; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D027981:Symporters / Q000737:chemistry* / Q000235:genetics
chemical_list: D026921:Amino Acid Transport Systems, Neutral; D029968:Escherichia coli Proteins; D027981:Symporters; C060609:PutP protein, E coli