5l6h
From Proteopedia
Uba1 in complex with Ub-ABPA3 covalent adduct
Structural highlights
Function[UBA1_YEAST] Activates ubiquitin by first adenylating its C-terminal glycine residue with ATP, and thereafter linking this residue to the side chain of a cysteine residue in E1, yielding an ubiquitin-E1 thioester and free AMP. [RS27A_YEAST] Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, and DNA-damage responses. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling (By similarity). 40S ribosomal protein S31 is a component of the 40S subunit of the ribosome (By similarity). Publication Abstract from PubMedTargeting the activating enzymes (E1) of ubiquitin (Ub) and ubiquitin-like modifiers (Ubls) has emerged as a promising anti-cancer strategy, possibly overcoming the ineffectiveness of proteasome inhibitors against solid tumors. Here, we report crystal structures of the yeast ubiquitin E1 (Uba1) with three adenosyl sulfamate inhibitors exhibiting different E1 specificities, which are all covalently linked to ubiquitin. The structures illustrate how the chemically diverse inhibitors are accommodated within the adenylation active site. When compared with the previously reported structures of various E1 enzymes, our structures provide the basis of the preferences of these inhibitors for different Ub/Ubl-activating enzymes. In vitro inhibition assays and molecular dynamics simulations validated the specificities of the inhibitors as deduced from the structures. Taken together, the structures establish a framework for the development of additional compounds targeting E1 enzymes, which will display higher potency and selectivity. Dissecting the Specificity of Adenosyl Sulfamate Inhibitors Targeting the Ubiquitin-Activating Enzyme.,Misra M, Kuhn M, Lobel M, An H, Statsyuk AV, Sotriffer C, Schindelin H Structure. 2017 Jul 5;25(7):1120-1129.e3. doi: 10.1016/j.str.2017.05.001. Epub, 2017 Jun 1. PMID:28578874[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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