title: A mutually assured destruction mechanism attenuates light signaling in Arabidopsis.
abstract: After light-induced nuclear translocation, phytochrome photoreceptors interact with and induce rapid phosphorylation and degradation of basic helix-loop-helix transcription factors, such as PHYTOCHROME-INTERACTING FACTOR 3 (PIF3), to regulate gene expression. Concomitantly, this interaction triggers feedback reduction of phytochrome B (phyB) levels. Light-induced phosphorylation of PIF3 is necessary for the degradation of both proteins. We report that this PIF3 phosphorylation induces, and is necessary for, recruitment of LRB [Light-Response Bric-a-Brack/Tramtrack/Broad (BTB)] E3 ubiquitin ligases to the PIF3-phyB complex. The recruited LRBs promote concurrent polyubiqutination and degradation of both PIF3 and phyB in vivo. These data reveal a linked signal-transmission and attenuation mechanism involving mutually assured destruction of the receptor and its immediate signaling partner.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 and U.S. Department of Agriculture/Agriculture Research Service, Plant Gene Expression Center, Albany, CA 94710.
authors.forename: Weimin
authors.initials: W
authors.lastname: Ni
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143.|Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305.
authors.forename: Shou-Ling
authors.initials: SL
authors.lastname: Xu
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 and U.S. Department of Agriculture/Agriculture Research Service, Plant Gene Expression Center, Albany, CA 94710.
authors.forename: James M
authors.initials: JM
authors.lastname: Tepperman
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143.
authors.forename: David J
authors.initials: DJ
authors.lastname: Stanley
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143.
authors.forename: Dave A
authors.initials: DA
authors.lastname: Maltby
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143.
authors.forename: John D
authors.initials: JD
authors.lastname: Gross
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143.
authors.forename: Alma L
authors.initials: AL
authors.lastname: Burlingame
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305.
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Wang
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 and U.S. Department of Agriculture/Agriculture Research Service, Plant Gene Expression Center, Albany, CA 94710.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Quail
mesh_terms: D021581:Active Transport, Cell Nucleus; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D044842:Cullin Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006367:HeLa Cells; D006801:Humans; D055537:Light Signal Transduction; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D051939:Phytochrome B / Q000378:metabolism*; D025821:Polyubiquitin / Q000378:metabolism; D059748:Proteolysis; D054875:Ubiquitination
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D044842:Cullin Proteins; D009687:Nuclear Proteins; D051939:Phytochrome B; D025821:Polyubiquitin; C000588971:LRB1 protein, Arabidopsis; C000588972:LRB2 protein, Arabidopsis; C000588973:LRB3 protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; C116162:PIF3 protein, Arabidopsis