title: Light-induced switching of HAMP domain conformation and dynamics revealed by time-resolved EPR spectroscopy.
abstract: HAMP domains are widely abundant signaling modules. The putative mechanism of their function comprises switching between two distinct states. To unravel these conformational transitions, we apply site-directed spin labeling and time-resolved EPR spectroscopy to the phototactic receptor/transducer complex NpSRII/NpHtrII. We characterize the kinetic coupling of NpHtrII to NpSRII along with the activation period of the transducer and follow the transient conformational signal. The observed transient shift towards a more compact state of the HAMP domain upon light-activation agrees with structure-based calculations. It thereby validates the two modeled signaling states and integrates the domain's dynamics into the current model.
authors.affiliation: Department of Physics, University of Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Klose
authors.affiliation: Department of Physics, University of Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany.
authors.forename: Natalia
authors.initials: N
authors.lastname: Voskoboynikova
authors.affiliation: Department of Physics, University of Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany.
authors.forename: Ioan
authors.initials: I
authors.lastname: Orban-Glass
authors.affiliation: Department of Physics, University of Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rickert
authors.affiliation: Max-Planck-Institute for Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Engelhard
authors.affiliation: Department of Physics, University of Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany.
authors.forename: Johann P
authors.initials: JP
authors.lastname: Klare
authors.affiliation: Department of Physics, University of Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany. Electronic address: hsteinho@uos.de.
authors.forename: Heinz-Jürgen
authors.initials: HJ
authors.lastname: Steinhoff
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry / Q000378:metabolism; D002338:Carotenoids / Q000737:chemistry / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D008027:Light; D008958:Models, Molecular; D017434:Protein Structure, Tertiary / Q000528:radiation effects
chemical_list: D019843:Archaeal Proteins; C434451:HtrII protein, Natronobacterium pharaonis; C434450:phototaxis receptor sensory rhodopsin II, Natronobacterium pharaonis; D002338:Carotenoids
keywords: Chemoreceptor; Chemotaxis; Coiled-coil signaling; HAMP domain; Phototaxis; Spin labeling