Internalization and vacuolar targeting of the brassinosteroid hormone receptor BRI1 are regulated by ubiquitination

• Published in: Nature communications 2015-01, Vol.6 (1), p.6151-6151, Article 6151
• Main Authors: Martins, Sara, Dohmann, Esther M. N., Cayrel, Anne, Johnson, Alexander, Fischer, Wolfgang, Pojer, Florence, Satiat-Jeunemaître, Béatrice, Jaillais, Yvon, Chory, Joanne, Geldner, Niko, Vert, Grégory
• Format: Article
• Language: English
• Subjects: 14; 14/19; 14/35; 631/449/2675; 631/80/313; 631/80/458/582; 631/80/86/2363; 82/80; 96/95; Antibodies; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Brassinosteroids; Brassinosteroids - metabolism; BRI1 protein; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cell surface; Chains; Endocytosis; Endosomes; Endosomes - metabolism; Endosomes - ultrastructure; Gene Expression Regulation, Plant; Golgi apparatus; Hormones; Humanities and Social Sciences; Internalization; Kinases; Life Sciences; Lysine - metabolism; Mammalian cells; Microscopy, Fluorescence - methods; Molecular weight; multidisciplinary; Mutation; Phosphorylation; Plant growth; Plants, Genetically Modified; Plasma; Polyubiquitin - genetics; Polyubiquitin - metabolism; Post-translation; Protein Kinases - genetics; Protein Kinases - metabolism; Protein Processing, Post-Translational; Protein Transport; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proteins; Proteolysis; Receptors; Science; Signal Transduction; Steroid hormones; trans-Golgi Network - metabolism; trans-Golgi Network - ultrastructure; Ubiquitination; Vacuoles - metabolism; Vacuoles - ultrastructure; Yeasts
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms7151

Brassinosteroids are plant steroid hormones that control many aspects of plant growth and development, and are perceived at the cell surface by the plasma membrane-localized receptor kinase BRI1. Here we show that BRI1 is post-translationally modified by K63 polyubiquitin chains in vivo . Using both artificial ubiquitination of BRI1 and generation of an ubiquitination-defective BRI1 mutant form, we demonstrate that ubiquitination promotes BRI1 internalization from the cell surface and is essential for its recognition at the trans -Golgi network/early endosomes (TGN/EE) for vacuolar targeting. Finally, we demonstrate that the control of BRI1 protein dynamics by ubiquitination is an important control mechanism for brassinosteroid responses in plants. Altogether, our results identify ubiquitination and K63-linked polyubiquitin chain formation as a dual targeting signal for BRI1 internalization and sorting along the endocytic pathway, and highlight its role in hormonally controlled plant development. Ubiquitination of cargo proteins regulates endocytosis in yeast and mammalian cells, however the extent to which this applies to plants is less clear. Martins et al . show that both internalization and vacuolar targetting of the Arabidopsis brassinosteroid receptor BRI1 are regulated by ubiquitination.