title: Light-induced conformational changes of the chromophore and the protein in phytochromes: bacterial phytochromes as model systems.
abstract: Recombinant phytochromes Agp1 and Agp2 from Agrobacterium tumefaciens are used as model phytochromes for biochemical and biophysical studies. In biliverdin binding phytochromes the site for covalent attachment of the chromophore lies in the N-terminal region of the protein, different from plant phytochromes. The issue which stereochemistry the chromophore adopts in the so-called Pr and Pfr forms is addressed by using a series of locked chromophores which form spectrally characteristic adducts with Agp1 and Agp2. Studies on light-induced conformational changes of Agp1 give an insight into how the intrinsic histidine kinase is modulated by light. Comparison of the crystal structure of an Agp1 fragment with other phytochrome crystal structures supports the idea that a light induced rearrangement of subunits within the homodimer modulates the activity of the kinase.
authors.affiliation: Institut für Medizinische Physik und Biophysik (CC2), Charité-Universitätsmedizin Berlin, Ziegelstr. 5-9, D-10117 Berlin, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Scheerer
authors.forename: Norbert
authors.initials: N
authors.lastname: Michael
authors.forename: Jung Hee
authors.initials: JH
authors.lastname: Park
authors.forename: Soshichiro
authors.initials: S
authors.lastname: Nagano
authors.forename: Hui-Woog
authors.initials: HW
authors.lastname: Choe
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Inomata
authors.forename: Berthold
authors.initials: B
authors.lastname: Borucki
authors.forename: Norbert
authors.initials: N
authors.lastname: Krauss
authors.forename: Tilman
authors.initials: T
authors.lastname: Lamparter
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D000071677:Histidine Kinase; D008027:Light; D010834:Phytochrome / Q000737:chemistry* / Q000145:classification; D011494:Protein Kinases / Q000737:chemistry*; D017434:Protein Structure, Tertiary
chemical_list: D010834:Phytochrome; D011494:Protein Kinases; D000071677:Histidine Kinase