title: 14-3-3 proteins participate in light signaling through association with PHYTOCHROME INTERACTING FACTORs.
abstract: 14-3-3 proteins are regulatory proteins found in all eukaryotes and are known to selectively interact with phosphorylated proteins to regulate physiological processes. Through an affinity purification screening, many light-related proteins were recovered as 14-3-3 candidate binding partners. Yeast two-hybrid analysis revealed that the 14-3-3 kappa isoform (14-3-3κ) could bind to PHYTOCHROME INTERACTING FACTOR3 (PIF3) and CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1). Further analysis by in vitro pull-down assay confirmed the interaction between 14-3-3κ and PIF3. Interruption of putative phosphorylation sites on the 14-3-3 binding motifs of PIF3 was not sufficient to inhibit 14-3-3κ from binding or to disturb nuclear localization of PIF3. It was also indicated that 14-3-3κ could bind to other members of the PIF family, such as PIF1 and PIF6, but not to LONG HYPOCOTYL IN FAR-RED1 (HFR1). 14-3-3 mutants, as well as the PIF3 overexpressor, displayed longer hypocotyls, and a pif3 mutant displayed shorter hypocotyls than the wild-type in red light, suggesting that 14-3-3 proteins are positive regulators of photomorphogenesis and function antagonistically with PIF3. Consequently, our results indicate that 14-3-3 proteins bind to PIFs and initiate photomorphogenesis in response to a light signal.
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan. eri.adams@riken.jp.
authors.forename: Eri
authors.initials: E
authors.lastname: Adams
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan. celine.diaz@cragenomica.es.
authors.forename: Celine
authors.initials: C
authors.lastname: Diaz
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan. jongpil.hong@riken.jp.
authors.forename: Jong-Pil
authors.initials: JP
authors.lastname: Hong
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan. ryoung.shin@riken.jp.
authors.forename: Ryoung
authors.initials: R
authors.lastname: Shin
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D008027:Light; D008954:Models, Biological; D009154:Mutation; D010641:Phenotype; D010788:Photosynthesis; D010834:Phytochrome / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D021381:Protein Transport; D015398:Signal Transduction / Q000528:radiation effects*; D020798:Two-Hybrid System Techniques
chemical_list: D048948:14-3-3 Proteins; D051792:Basic Helix-Loop-Helix Proteins; D010834:Phytochrome