title: Heteronuclear NMR investigation on the structure and dynamics of the chromophore binding pocket of the cyanobacterial phytochrome Cph1.
abstract: Structural changes of the chromophore in phytochrome proteins associated with its photocycle are still not fully understood. We use heteronuclear NMR to investigate the conformation and dynamics of the chromophore in the binding pocket of the cyanobacterial phytochrome Cph1. On the basis of distance information obtained from three-dimensional nuclear Overhauser enhancement (3D-NOESY) spectra using the photochemically intact photosensory module of Cph1 we demonstrate that the chromophore is in the ZZZssa form in the P(r) (red absorbing form) state and the ZZEssa form in the P(fr) (far-red absorbing form) state of the protein. While ZZZssa for the P(r) state is in agreement with a recently determined X-ray structure, no comparable information for the P(fr) state of photochemically intact phytochrome has been available up to now. In addition, the chromophore in the binding pocket of Cph1 exhibits a notable mobility, which is distinctly different in the two photostates.
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, D-13125 Berlin, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Hahn
authors.forename: Holger M
authors.initials: HM
authors.lastname: Strauss
authors.forename: Peter
authors.initials: P
authors.lastname: Schmieder
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D000458:Cyanobacteria; D008968:Molecular Conformation; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010777:Photochemistry; D020283:Photoreceptors, Microbial; D010834:Phytochrome / Q000737:chemistry*; D011494:Protein Kinases / Q000737:chemistry*; D012015:Reference Standards; D013696:Temperature; D045725:Tetrapyrroles / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; D045725:Tetrapyrroles; D010834:Phytochrome; D011494:Protein Kinases; C413623:Cph1 phytochrome protein, bacteria