4i92 | pdb_00004i92
Structure of the BSK8 kinase domain
Structural highlights
FunctionBSK8_ARATH Probable serine/threonine kinase that acts as positive regulator of brassinosteroid (BR) signaling downstream of the receptor kinase BRI1. Functions redundantly with BSK3, BSK4, BSK6 and BSK7 (PubMed:23496207). Involved in the regulation of sucrose-phosphate synthase 1 (SPS1) in the context of sucrose resuply after starvation. Activates BSL2, a phosphatase that may dephosphorylate SPS1, leading to the activation of SPS1 (PubMed:24924143).[1] [2] Publication Abstract from PubMedBrassinosteroid signaling kinases (BSKs) are plant-specific receptor-like cytoplasmic protein kinases involved in the brassinosteroid signaling pathway. Unlike common protein kinases, they possess a naturally occurring alanine residue at the "gatekeeper" position, as well as other sequence variations. How BSKs activate downstream proteins such as BSU1, as well as the structural consequences of their unusual sequential features, was unclear. We crystallized the catalytic domain of BSK8 and solved its structure by multiple-wavelength anomalous dispersion phasing methods to a resolution of 1.5A. In addition, a co-crystal structure of BSK8 with 5-adenylyl imidodiphosphate (AMP-PNP) revealed unusual conformational arrangements of the nucleotide phosphate groups and catalytic key motifs, typically not observed for active protein kinases. Sequential analysis and comparisons with known pseudokinase structures suggest that BSKs represent constitutively inactive protein kinases that regulate brassinosteroid signal transfer through an allosteric mechanism. Structural Characterization of the RLCK Family Member BSK8: A Pseudokinase with an Unprecedented Architecture.,Grutter C, Sreeramulu S, Sessa G, Rauh D J Mol Biol. 2013 Aug 2. pii: S0022-2836(13)00482-8. doi:, 10.1016/j.jmb.2013.07.034. PMID:23911552[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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