title: Structural insights into the early steps of receptor-transducer signal transfer in archaeal phototaxis.
abstract: Electron paramagnetic resonance-based inter-residue distance measurements between site-directed spin-labelled sites of sensory rhodopsin II (NpSRII) and its transducer NpHtrII from Natronobacterium pharaonis revealed a 2:2 complex with 2-fold symmetry. The core of the complex is formed by the four transmembrane helices of a transducer dimer. Upon light excitation, the previously reported flap-like movement of helix F of NpSRII induces a conformational change in the transmembrane domain of the transducer. The inter-residue distance changes determined provide strong evidence for a rotary motion of the second transmembrane helix of the transducer. This helix rotation becomes uncoupled from changes in the receptor during the last step of the photocycle.
authors.affiliation: Max-Planck-Institut für Molekulare Physiologie, Otto Hahn-Strasse 11, D-44227 Dortmund, Germany.
authors.forename: A A
authors.initials: AA
authors.lastname: Wegener
authors.forename: J P
authors.initials: JP
authors.lastname: Klare
authors.forename: M
authors.initials: M
authors.lastname: Engelhard
authors.forename: H J
authors.initials: HJ
authors.lastname: Steinhoff
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects*; D002338:Carotenoids / Q000737:chemistry / Q000528:radiation effects*; D019281:Dimerization; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D008958:Models, Molecular; D009068:Movement / Q000502:physiology*; D019633:Natronobacterium; D020283:Photoreceptors, Microbial / Q000737:chemistry / Q000528:radiation effects*; D015398:Signal Transduction
chemical_list: D019843:Archaeal Proteins; C434451:HtrII protein, Natronobacterium pharaonis; D020283:Photoreceptors, Microbial; C434450:phototaxis receptor sensory rhodopsin II, Natronobacterium pharaonis; D002338:Carotenoids