5um3
Crystal structure of the V122L mutant of human UBR-box domain from UBR2
Structural highlights
FunctionUBR2_HUMAN E3 ubiquitin-protein ligase which is a component of the N-end rule pathway. Recognizes and binds to proteins bearing specific N-terminal residues that are destabilizing according to the N-end rule, leading to their ubiquitination and subsequent degradation. Plays a critical role in chromatin inactivation and chromosome-wide transcriptional silencing during meiosis via ubiquitination of histone H2A. Binds leucine and is a negative regulator of the leucine-mTOR signaling pathway, thereby controlling cell growth.[1] [2] [3] Publication Abstract from PubMedThe N-end rule pathway controls the half-life of proteins based on their N-terminal residue. Positively charged type 1 N-degrons are recognized by a negatively charged pocket on the Zn finger named the UBR box. Here, we show that the UBR box is rigid, but bound water molecules in the pocket provide the structural plasticity required to bind different positively charged amino acids. Ultra-high-resolution crystal structures of arginine, histidine, and methylated arginine reveal that water molecules mediate the binding of N-degron peptides. Using a high-throughput binding assay and isothermal titration calorimetry, we demonstrate that the UBR box is able to bind methylated arginine and lysine peptides with high affinity and measure the preference for hydrophobic residues in the second position in the N-degron peptide. Finally, we show that the V122L mutation present in Johanson-Blizzard syndrome patients changes the specificity for the second position due to occlusion of the secondary pocket. Bound Waters Mediate Binding of Diverse Substrates to a Ubiquitin Ligase.,Munoz-Escobar J, Matta-Camacho E, Cho C, Kozlov G, Gehring K Structure. 2017 Mar 27. pii: S0969-2126(17)30064-3. doi:, 10.1016/j.str.2017.03.004. PMID:28392261[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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