5tte
From Proteopedia
Crystal Structure of an RBR E3 ubiquitin ligase in complex with an E2-Ub thioester intermediate mimic
Structural highlights
Function[ARI1_HUMAN] E3 ubiquitin-protein ligase, which catalyzes polyubiquitination of target proteins together with ubiquitin-conjugating enzyme E2 UBE2L3. May play a role in protein translation by mediating polyubiquitination of EIF4E2, leading to its subsequent degradation.[1] [2] [3] [UB2L3_HUMAN] Ubiquitin-conjugating enzyme E2 that specifically acts with HECT-type and RBR family E3 ubiquitin-protein ligases. Does not function with most RING-containing E3 ubiquitin-protein ligases because it lacks intrinsic E3-independent reactivity with lysine: in contrast, it has activity with the RBR family E3 enzymes, such as PARK2 and ARIH1, that function like function like RING-HECT hybrids. Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. In vitro catalyzes 'Lys-11'-linked polyubiquitination. Involved in the selective degradation of short-lived and abnormal proteins. Down-regulated during the S-phase it is involved in progression through the cell cycle. Regulates nuclear hormone receptors transcriptional activity. May play a role in myelopoiesis.[4] [5] [6] [7] [8] [9] [10] Publication Abstract from PubMedRING-in-between-RING (RBR) ubiquitin (Ub) E3 ligases function with Ub E2s through a RING/HECT hybrid mechanism to conjugate Ub to target proteins. Here, we report the crystal structure of the RBR E3, HHARI, in complex with a UbcH7 ~ Ub thioester mimetic which reveals the molecular basis for the specificity of this cognate E2/RBR E3 pair. The structure also reveals mechanistically important conformational changes in the RING1 and UBA-like domains of HHARI that accompany UbcH7 ~ Ub binding and provides a molecular basis by which HHARI recruits E2 ~ Ub in an 'open' conformation. In addition to optimally functioning with an E2 that solely performs transthiolation, our data suggests that HHARI prevents spurious discharge of Ub from E2 to lysine residues by: (1) harboring structural elements that block E2 ~ Ub from adopting a 'closed' conformation and (2) participating in contacts to ubiquitin that promote an open E2 ~ Ub conformation.HHARI is a RING-in-between-RING (RBR) ubiquitin (Ub) E3 ligase. Here the authors present the crystal structure of HHARI with the UbcH7 ~ Ub thioester intermediate mimetic, which reveals that HHARI binds this E2 ~ Ub in an open conformation and explains the specificity of this cognate RBR E3/E2 pair. Structural insights into the mechanism and E2 specificity of the RBR E3 ubiquitin ligase HHARI.,Yuan L, Lv Z, Atkison JH, Olsen SK Nat Commun. 2017 Aug 8;8(1):211. doi: 10.1038/s41467-017-00272-6. PMID:28790309[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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