title: Arabidopsis FHY3 defines a key phytochrome A signaling component directly interacting with its homologous partner FAR1.
abstract: In Arabidopsis, phytochrome A (phyA) is the primary photoreceptor mediating various plant responses to far-red (FR) light. Here we show that phyA signaling involves a combinatorial action of downstream intermediates, which controls overlapping yet distinctive sets of FR responses. FHY3 is a prominent phyA signaling intermediate sharing structural similarity to FAR1, a previously identified phyA signaling component. The fhy3 and far1 mutants display similar yet distinctive defects in phyA signaling; however, overexpression of either FHY3 or FAR1 suppresses the mutant phenotype of both genes. Moreover, overexpression of partial fragments of FHY3 can cause a dominant-negative interference phenotype on phyA signaling that is stronger than those of the fhy3 or far1 null mutants. Further, we demonstrate that FHY3 and FAR1 are capable of homo- and hetero-interaction. Our data indicate that FHY3, together with FAR1, defines a key module in a signaling network underlying phyA-mediated FR light responses.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8104, USA.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Wang
authors.forename: Xing Wang
authors.initials: XW
authors.lastname: Deng
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008027:Light; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D045322:Photosynthetic Reaction Center Complex Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010834:Phytochrome / Q000378:metabolism*; D051942:Phytochrome A; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; C120919:FAR1 protein, Arabidopsis; C452847:FHY3 protein, Arabidopsis; D009687:Nuclear Proteins; C497973:PHYA protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D051942:Phytochrome A; D010834:Phytochrome