Please use this identifier to cite or link to this item:
Title: Crystal structures of the phosphorylated BRI1 kinase domain and implications for brassinosteroid signal initiation
Authors: Bojar, D.
Martinez, J.
Santiago, J.
Rybin, V.
Bayliss, Richard
Hothorn, M.
First Published: 12-Mar-2014
Publisher: Wiley, Society for Experimental Biology (SEB)
Citation: The Plant Journal (2014) 78, 31–43
Abstract: Brassinosteroids, which control plant growth and development, are sensed by the membrane receptor kinase BRASSINOSTEROID INSENSITIVE 1 (BRI1). Brassinosteroid binding to the BRI1 leucine-rich repeat (LRR) domain induces heteromerisation with a SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK)-family co-receptor. This process allows the cytoplasmic kinase domains of BRI1 and SERK to interact, trans-phosphorylate and activate each other. Here we report crystal structures of the BRI1 kinase domain in its activated form and in complex with nucleotides. BRI1 has structural features reminiscent of both serine/threonine and tyrosine kinases, providing insight into the evolution of dual-specificity kinases in plants. Phosphorylation of Thr1039, Ser1042 and Ser1044 causes formation of a catalytically competent activation loop. Mapping previously identified serine/threonine and tyrosine phosphorylation sites onto the structure, we analyse their contribution to brassinosteroid signaling. The location of known genetic missense alleles provide detailed insight into the BRI1 kinase mechanism, while our analyses are inconsistent with a previously reported guanylate cyclase activity. We identify a protein interaction surface on the C-terminal lobe of the kinase and demonstrate that the isolated BRI1, SERK2 and SERK3 cytoplasmic segments form homodimers in solution and have a weak tendency to heteromerise. We propose a model in which heterodimerisation of the BRI1 and SERK ectodomains brings their cytoplasmic kinase domains in a catalytically competent arrangement, an interaction that can be modulated by the BRI1 inhibitor protein BKI1.
DOI Link: 10.1111/tpj.12445
ISSN: 0960-7412
eISSN: 1365-313X
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: © 2014 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Description: Atomic coordinates and structure factors have been deposited with the Protein Data Bank with accession codes 4OA2 (BRI1865–1196 ADP), 4OA6 (BRI1865–1160 apo), 4OA9 (BRI1865–1160 Mn2+/AppNHp), 4OAB (BRI1865–1160 ATP) and 4OAC (BRI1865–1160 ADP).
Appears in Collections:Published Articles, Dept. of Biochemistry

Files in This Item:
File Description SizeFormat 
Bojar_et_al-2014-The_Plant_Journal.pdfPublisher version1.97 MBAdobe PDFView/Open

Items in LRA are protected by copyright, with all rights reserved, unless otherwise indicated.