title: Photochemical chromophore isomerization in histidine kinase rhodopsin HKR1.
abstract: Histidine kinase rhodopsin 1 is a photoreceptor in green algae functioning as a UV-light sensor. It switches between a UV-absorbing state (Rh-UV) and a blue-absorbing state (Rh-Bl) with a protonated retinal Schiff base (RSB) cofactor in a mixture of 13-trans,15-anti and 13-cis,15-syn isomers. The present spectroscopic study now shows that cofactor-protein assembly stabilizes the protonated 13-trans,15-anti RSB isomer. Formation of the active photoswitch requires the photoinduced conversion to Rh-UV. The transitions between the Rh-Bl isomers and the deprotonated 13-cis,15-anti and 13-trans,15-syn isomers of Rh-UV proceed via multiple photoisomerizations of one or simultaneously two double bonds.
authors.affiliation: Humboldt Universität zu Berlin, Institut für Biologie, Experimentelle Biophysik, Invalidenstr. 42, D-10115 Berlin, Germany.
authors.forename: Meike
authors.initials: M
authors.lastname: Luck
authors.affiliation: Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße des 17. Juni 135, D-10623 Berlin, Germany.
authors.forename: Sara
authors.initials: S
authors.lastname: Bruun
authors.affiliation: Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße des 17. Juni 135, D-10623 Berlin, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Keidel
authors.affiliation: Humboldt Universität zu Berlin, Institut für Biologie, Experimentelle Biophysik, Invalidenstr. 42, D-10115 Berlin, Germany. Electronic address: hegemann@rz.hu-berlin.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Hegemann
authors.affiliation: Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße des 17. Juni 135, D-10623 Berlin, Germany. Electronic address: hildebrandt@chem.tu-berlin.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Hildebrandt
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics; D000071677:Histidine Kinase; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012172:Retinaldehyde / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012545:Schiff Bases; D014466:Ultraviolet Rays
chemical_list: D010940:Plant Proteins; D012545:Schiff Bases; D012243:Rhodopsin; D011494:Protein Kinases; D000071677:Histidine Kinase; D012172:Retinaldehyde
keywords: Histidine kinase; Isomerization; Microbial rhodopsin; Photoswitch; Resonance Raman