title: Light-dependent translocation of a phytochrome B-GFP fusion protein to the nucleus in transgenic Arabidopsis.
abstract: Phytochrome is a ubiquitous photoreceptor of plants and is encoded by a small multigene family. We have shown recently that a functional nuclear localization signal may reside within the COOH-terminal region of a major member of the family, phytochrome B (phyB) (Sakamoto, K., and A. Nagatani. 1996. Plant J. 10:859-868). In the present study, a fusion protein consisting of full-length phyB and the green fluorescent protein (GFP) was overexpressed in the phyB mutant of Arabidopsis to examine subcellular localization of phyB in intact tissues. The resulting transgenic lines exhibited pleiotropic phenotypes reported previously for phyB overexpressing plants, suggesting that the fusion protein is biologically active. Immunoblot analysis with anti-phyB and anti-GFP monoclonal antibodies confirmed that the fusion protein accumulated to high levels in these lines. Fluorescence microscopy of the seedlings revealed that the phyB-GFP fusion protein was localized to the nucleus in light grown tissues. Interestingly, the fusion protein formed speckles in the nucleus. Analysis of confocal optical sections confirmed that the speckles were distributed within the nucleus. In contrast, phyB-GFP fluorescence was observed throughout the cell in dark-grown seedlings. Therefore, phyB translocates to specific sites within the nucleus upon photoreceptor activation.
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Yamaguchi
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.forename: N
authors.initials: N
authors.lastname: Mochizuki
authors.forename: S A
authors.initials: SA
authors.lastname: Kay
authors.forename: A
authors.initials: A
authors.lastname: Nagatani
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins; D002467:Cell Nucleus / Q000378:metabolism*; D003116:Color; D003624:Darkness; D049452:Green Fluorescent Proteins; D018546:Hypocotyl / Q000502:physiology; D015151:Immunoblotting; D007202:Indicators and Reagents / Q000493:pharmacokinetics*; D008029:Lighting; D008164:Luminescent Proteins / Q000032:analysis / Q000493:pharmacokinetics*; D018613:Microscopy, Confocal; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000378:metabolism; D010775:Photic Stimulation; D010786:Photoreceptor Cells; D010834:Phytochrome / Q000032:analysis / Q000493:pharmacokinetics*; D051939:Phytochrome B; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000493:pharmacokinetics; D014157:Transcription Factors
chemical_list: D029681:Arabidopsis Proteins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; C497952:PHYB protein, Arabidopsis; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D010834:Phytochrome; D051939:Phytochrome B; D049452:Green Fluorescent Proteins