4q5j
From Proteopedia
Crystal structure of SeMet derivative BRI1 in complex with BKI1
Structural highlights
Function[BRI1_ARATH] Receptor with a dual specificity kinase activity acting on both serine/threonine- and tyrosine-containing substrates. Regulates, in response to brassinosteroid binding, a signaling cascade involved in plant development, including expression of light- and stress-regulated genes, promotion of cell elongation, normal leaf and chloroplast senescence, and flowering. Binds brassinolide, and less effectively castasterone, but not 2,3,22,23-O-tetramethylbrassinolide or ecdysone. May be involved in a feedback regulation of brassinosteroid biosynthesis. Phosphorylates BRI1-associated receptor kinase 1 (BAK1), Transthyretin-Like protein (TTL) and SERK1 on 'Ser-299' and 'Thr-462' in vitro. May have a guanylyl cyclase activity.[1] [2] [3] [4] [5] [6] [BKI1_ARATH] Negative regulator of brassinosteroid signaling. When associated to the membrane, limits the interaction of BRI1 with BAK1 by binding to the kinase-inactive form of BRI1.[7] Publication Abstract from PubMedBrassinosteroids (BRs) are essential steroid hormones that have crucial roles in plant growth and development. BRs are perceived by the cell-surface receptor-like kinase brassinosteroid insensitive 1 (BRI1). In the absence of BRs, the cytosolic kinase domain (KD) of BRI1 is inhibited by its auto-inhibitory carboxyl terminus, as well as by interacting with an inhibitor protein, BRI1 kinase inhibitor 1 (BKI1). How BR binding to the extracellular domain of BRI1 leads to activation of the KD and dissociation of BKI1 into the cytosol remains unclear. Here we report the crystal structure of BRI1 KD in complex with the interacting peptide derived from BKI1. We also provide biochemical evidence that BRI1-associated kinase 1 (BAK1) plays an essential role in initiating BR signaling. Steroid-dependent heterodimerization of BRI1 and BAK1 ectodomains brings their cytoplasmic KDs in the right orientation for competing with BKI1 and transphosphorylation.Cell Research advance online publication 21 October 2014; doi:10.1038/cr.2014.132. Structural insights into the negative regulation of BRI1 signaling by BRI1-interacting protein BKI1.,Wang J, Jiang J, Wang J, Chen L, Fan SL, Wu JW, Wang X, Wang ZX Cell Res. 2014 Oct 21. doi: 10.1038/cr.2014.132. PMID:25331450[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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