The brassinosteroid insensitive1-like3 signalosome complex regulates Arabidopsis root development.
Brassinosteroid (BR) hormones are primarily perceived at the cell surface by the leucine-rich repeat receptor-like kinase brassinosteroid insensitive1 (BRI1). In Arabidopsis thaliana, BRI1 has two close homologs, BRI1-LIKE1 (BRL1) and BRL3, respectively, which are expressed in the vascular tissues and regulate shoot vascular development. Here, we identify novel components of the BRL3 receptor complex in planta by immunoprecipitation and mass spectrometry analysis. Whereas BRI1 associated kinase1 (BAK1) and several other known BRI1 interactors coimmunoprecipitated with BRL3, no evidence was found of a direct interaction between BRI1 and BRL3. In addition, we confirmed that BAK1 interacts with the BRL1 receptor by coimmunoprecipitation and fluorescence microscopy analysis. Importantly, genetic analysis of brl1 brl3 bak1-3 triple mutants revealed that BAK1, BRL1, and BRL3 signaling modulate root growth and development by contributing to the cellular activities of provascular and quiescent center cells. This provides functional relevance to the observed protein-protein interactions of the BRL3 signalosome. Overall, our study demonstrates that cell-specific BR receptor complexes can be assembled to perform different cellular activities during plant root growth, while highlighting that immunoprecipitation of leucine-rich repeat receptor kinases in plants is a powerful approach for unveiling signaling mechanisms with cellular resolution in plant development.
Department of Molecular Genetics, Centre de Recerca en Agrigenòmica, 08193 Barcelona, Spain.
Norma
N
Fàbregas
Na
N
Li
Sjef
S
Boeren
Tara E
TE
Nash
Michael B
MB
Goshe
Steven D
SD
Clouse
Sacco
S
de Vries
Ana I
AI
Caño-Delgado
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060406:Brassinosteroids / Q000378:metabolism; D002453:Cell Cycle; D002853:Chromatography, Liquid; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D046912:Multiprotein Complexes; D009154:Mutation; D010641:Phenotype; D052585:Phloem / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D015398:Signal Transduction; D053719:Tandem Mass Spectrometry
D029681:Arabidopsis Proteins; C494334:BRL1 protein, Arabidopsis; C494335:BRL3 protein, Arabidopsis; D060406:Brassinosteroids; D046912:Multiprotein Complexes; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C463660:BAK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases