title: Characterization of a strong dominant phytochrome A mutation unique to phytochrome A signal propagation.
abstract: Here, we report the isolation and characterization of a strong dominant-negative phytochrome A (phyA) mutation (phyA-300D) in Arabidopsis. This mutation carries a single amino acid substitution at residue 631, from valine to methionine (V631M), in the core region within the C-terminal half of PHYA. This PHYA core region contains two protein-interactive motifs, PAS1 and PAS2. Val-631 is located within the PAS1 motif. The phyA-V631M mutant protein is photochemically active and accumulates to a level similar to wild type in dark-grown seedlings. Overexpression of PHYA-V631M in a wild-type background results in a dominant-negative interference with endogenous wild-type phyA, whereas PHYA-V631M in a phyA null mutant background is inactive. To investigate the specificity of this mutation within the phytochrome family, the corresponding amino acid substitution (V664M) was created in the PHYTOCHROME B (PHYB) polypeptide. We found that the phyB-V664M mutant protein is physiologically active in phyB mutant and causes no interfering effect in a wild-type background. Together, our results reveal a unique feature in phyA signal propagation through the C-terminal core region.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06511-8104, USA.
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Fry
authors.forename: Jessica
authors.initials: J
authors.lastname: Habashi
authors.forename: Haruko
authors.initials: H
authors.lastname: Okamoto
authors.forename: Xing Wang
authors.initials: XW
authors.lastname: Deng
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins; D003624:Darkness; D005799:Genes, Dominant; D018546:Hypocotyl / Q000254:growth & development; D008027:Light; D020125:Mutation, Missense; D010786:Photoreceptor Cells; D010834:Phytochrome / Q000235:genetics* / Q000502:physiology; D051942:Phytochrome A; D051939:Phytochrome B; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000528:radiation effects; D014157:Transcription Factors
chemical_list: D029681:Arabidopsis Proteins; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D051942:Phytochrome A; D014157:Transcription Factors; D010834:Phytochrome; D051939:Phytochrome B