title: The role of a 14-3-3 protein in stomatal opening mediated by PHOT2 in Arabidopsis.
abstract: The 14-3-3 λ isoform is required for normal stomatal opening mediated by PHOT2 in Arabidopsis thaliana. Arabidopsis phototropin2 (PHOT2) interacts with the λ-isoform 14-3-3 protein both in yeast two-hybrid screening and in an in vitro pull-down assay. Further yeast two-hybrid analysis also showed that the PHOT2 C-terminal kinase domain was required for the interaction. Site-directed mutagenesis indicated that PHOT2 Ser-747 is essential for the yeast interaction. Phenotypic characterization of a loss-of-function 14-3-3 λ mutant in a phot1 mutant background showed that the 14-3-3 λ protein was necessary for normal PHOT2-mediated blue light-induced stomatal opening. PHOT2 Ser-747 was necessary for complementation of the blue light-activated stomatal response in a phot1 phot2 double mutant. The 14-3-3 λ mutant in the phot1 mutant background allowed normal phototropism and normal chloroplast accumulation and avoidance responses. It also showed normal stomatal opening mediated by PHOT1 in a phot2 mutant background. The 14-3-3 κ mutant had no effect on stomatal opening in response to blue light. Although the 14-3-3 λ mutant had no chloroplast movement phenotype, the 14-3-3 κ mutation caused a weaker avoidance response at an intermediate blue light intensity by altering the balance between the avoidance and accumulation responses. The results highlight the strict specificity of phototropin-mediated signal transduction pathways.
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA.
authors.forename: Tong-Seung
authors.initials: TS
authors.lastname: Tseng
authors.forename: Craig
authors.initials: C
authors.lastname: Whippo
authors.forename: Roger P
authors.initials: RP
authors.lastname: Hangarter
authors.forename: Winslow R
authors.initials: WR
authors.lastname: Briggs
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000502:physiology; D005816:Genetic Complementation Test; D008027:Light; D016297:Mutagenesis, Site-Directed; D018524:Phototropism; D054046:Plant Stomata / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D020033:Protein Isoforms; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
chemical_list: D048948:14-3-3 Proteins; D029681:Arabidopsis Proteins; C423903:PHOT2 protein, Arabidopsis; D020033:Protein Isoforms