title: Time-Resolved Detection of Light-Induced Dimerization of Monomeric Aureochrome-1 and Change in Affinity for DNA.
abstract: Aureochrome (Aureo) is a recently discovered blue light sensor protein initially from Vaucheria frigida, in which it controls blue light-dependent branch formation and/or development of a sex organ by a light-dependent change in the affinity for DNA. Although photochemical reactions of Aureo-LOV (LOV is a C-terminal light-oxygen-voltage domain) and the N-terminal truncated construct containing a bZIP (N-terminal basic leucine zipper domain) and a LOV domain have previously been reported, the reaction kinetics of the change in affinity for DNA have never been elucidated. The reactions of Aureo where the cysteines are replaced by serines (AureoCS) as well as the kinetics of the change in affinity for a target DNA are investigated in the time-domain. The dimerization rate constant is obtained as 2.8 × 10(4) M(-1) s(-1), which suggests that the photoinduced dimerization occurs in the LOV domain and the bZIP domain dimerizes using the interaction with DNA. Surprisingly, binding with the target DNA is completed very quickly, 7.7 × 10(4) M(-1) s(-1), which is faster than the protein dimerization rate. It is proposed that the nonspecific electrostatic interaction, which is observed as a weak binding with DNA, may play a role in the efficient searching for the target sequence within the DNA.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University , Kyoto 606-8502, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Akiyama
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University , Kyoto 606-8502, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakasone
authors.affiliation: Department of Earth and Space Science, Graduate School of Science, Osaka University , Osaka 560-0043, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Nakatani
authors.affiliation: Department of Earth and Space Science, Graduate School of Science, Osaka University , Osaka 560-0043, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Hisatomi
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University , Kyoto 606-8502, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Terazima
mesh_terms: D020418:Algal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D000067493:Dynamic Light Scattering; D007700:Kinetics; D008027:Light; D030011:Ochrosia / Q000378:metabolism*; D011485:Protein Binding; D000072417:Protein Domains; D055503:Protein Multimerization / Q000528:radiation effects*; D055672:Static Electricity
chemical_list: D020418:Algal Proteins; D004247:DNA