title: Quaternary structure of LOV-domain containing polypeptide of Arabidopsis FKF1 protein.
abstract: Flavin-binding, Kelch repeat, F-box (FKF1) protein is a photoreceptor to regulate flowering of Arabidopsis. The protein has a light, oxygen and voltage (LOV)-sensing domain binding a flavin mononucleotide. The photo-activation of the domain is an indispensable step to initiate the cellular signaling for flowering. In the present study, a LOV-containing polypeptide of FKF1 was prepared by an overexpression system, and the quaternary structure of it was studied by size exclusion chromatography and small-angle X-ray scattering. The apparent molecular weight from chromatography suggested a globular trimeric or an anisotropic-shaped dimeric association of the polypeptide in solution. The scattering experiment demonstrated a dimeric association of the polypeptides with an elongated molecular shape displaying the radius of gyration of 27 A and the maximum dimension of 94 A. The molecular shape simulated from scattering profiles suggests an antiparallel association of the LOV domains in the dimer. Though the absorption spectrum of blue-light irradiated polypeptide was stable in the photoactivated state for a long period, the scattering profiles showed very small changes between the dark and light conditions. Based on the homologies in the amino-acid sequences and the scattering profiles, these results are discussed in connection with the structures and function of LOV domains of phototropin.
authors.affiliation: Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Kanagawa 223-8522, Japan. nakasako@phys.keio.ac.jp
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakasako
authors.forename: Daisuke
authors.initials: D
authors.lastname: Matsuoka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Zikihara
authors.forename: Satoru
authors.initials: S
authors.lastname: Tokutomi
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry*; D029681:Arabidopsis Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D013057:Spectrum Analysis
chemical_list: D029681:Arabidopsis Proteins; C410504:FKF1 protein, Arabidopsis; D010446:Peptide Fragments