title: Dual role of BKI1 and 14-3-3 s in brassinosteroid signaling to link receptor with transcription factors.
abstract: The plasma membrane-localized plant steroid hormone receptor, BRASSINOSTEROID INSENSITIVE 1 (BRI1), is quiescent in the absence of steroids, largely due to a negative regulator, BRI1 KINASE INHIBITOR 1 (BKI1). Here, we report that the steroid-induced, plasma membrane-dissociated and phosphorylated BKI1 also plays positive roles in BR signaling by interacting with a subset of 14-3-3 proteins. The cytosolic fraction of BKI1 carboxyl terminal region enhances BR signaling. Mutations of two serine residues in this region lead to reduced phosphorylation by the BRI1 kinase and constitutive plasma membrane localization. The 14-3-3 proteins can interact with the phosphorylated BKI1 through a motif that contains the two phosphorylation sites to release inhibition of BRI1 by BKI1. Meanwhile, the cytosolic BKI1 antagonizes the 14-3-3 s and enhances accumulation of BRI1 EMS SUPPRESSOR 1 (BES1)/BRASSINAZOLE RESISTANT 1 (BZR1) in the nucleus to regulate BR-responses.
authors.affiliation: State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China.
authors.forename: Haijiao
authors.initials: H
authors.lastname: Wang
authors.forename: Cangjin
authors.initials: C
authors.lastname: Yang
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.forename: Niyan
authors.initials: N
authors.lastname: Wang
authors.forename: Dihong
authors.initials: D
authors.lastname: Lu
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Shanshan
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhi-Xin
authors.initials: ZX
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
authors.forename: Xuelu
authors.initials: X
authors.lastname: Wang
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D060406:Brassinosteroids / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D020869:Gene Expression Profiling; D010766:Phosphorylation; D010940:Plant Proteins / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D060406:Brassinosteroids; D010940:Plant Proteins; D014157:Transcription Factors; D011494:Protein Kinases