title: Conformational changes of the histidine ATP-binding cassette transporter studied by double electron-electron resonance spectroscopy.
abstract: The conformational dynamics of the histidine ABC transporter HisQMP2 from Salmonella enterica serovar Typhimurium, reconstituted into liposomes, is studied by site-directed spin labeling and double electron-electron resonance spectroscopy in the absence of nucleotides, in the ATP-bound, and in the post-hydrolysis state. The results show that the inter-dimer distances as measured between the Q-loops of HisP2 in the intact transporter resemble those determined for the maltose transporter in all three states of the hydrolysis cycle. Only in the presence of liganded HisJ the closed conformation of the nucleotide binding sites is achieved revealing the transmembrane communication of the presence of substrate. Two conformational states can be distinguished for the periplasmic moiety of HisQMP2 as detected by differences in distributions of interspin distances between positions 86 and 96 or 104 and 197. The observed conformational changes are correlated to proposed open, semi-open and closed conformations of the nucleotide binding domains HisP2. Our results are in line with a rearrangement of transmembrane helices 4 and 4' of HisQM during the closed to the semi-open transition of HisP2 driven by the reorientation of the coupled helices 3a and 3b to occur upon hydrolysis.
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastr.7, 49076 Osnabrück, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Sippach
authors.affiliation: Institut für Biologie, AG Bakterienphysiologie, Humboldt Universität zu Berlin, Chausseestr. 117, D-10115 Berlin, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Weidlich
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastr.7, 49076 Osnabrück, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Klose
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastr.7, 49076 Osnabrück, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Abé
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastr.7, 49076 Osnabrück, Germany.
authors.forename: Johann
authors.initials: J
authors.lastname: Klare
authors.affiliation: Institut für Biologie, AG Bakterienphysiologie, Humboldt Universität zu Berlin, Chausseestr. 117, D-10115 Berlin, Germany.
authors.forename: Erwin
authors.initials: E
authors.lastname: Schneider
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastr.7, 49076 Osnabrück, Germany. Electronic address: hsteinho@uos.de.
authors.forename: Heinz-Jürgen
authors.initials: HJ
authors.lastname: Steinhoff
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry; D006639:Histidine / Q000378:metabolism; D006868:Hydrolysis; D008081:Liposomes / Q000737:chemistry; D008958:Models, Molecular; D017433:Protein Structure, Secondary
chemical_list: D018528:ATP-Binding Cassette Transporters; D029968:Escherichia coli Proteins; D008081:Liposomes; D006639:Histidine; D000255:Adenosine Triphosphate
keywords: ABC transporter; Double electron–electron resonance; EPR; Histidine transporter; Site-directed spin labeling