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From Proteopedia
Crystal Structure of Ankyrin Repeat and Socs Box-Containing Protein 9 (Asb9) in Complex with Elonginb and Elonginc
Structural highlights
Function[ASB9_HUMAN] Substrate-recognition component of a SCF-like ECS (Elongin-Cullin-SOCS-box protein) E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins. Recognizes at least two forms of creatine kinase, CKB and CKMT1A.[1] [2] [ELOB_HUMAN] SIII, also known as elongin, is a general transcription elongation factor that increases the RNA polymerase II transcription elongation past template-encoded arresting sites. Subunit A is transcriptionally active and its transcription activity is strongly enhanced by binding to the dimeric complex of the SIII regulatory subunits B and C (elongin BC complex).[3] [4] The elongin BC complex seems to be involved as an adapter protein in the proteasomal degradation of target proteins via different E3 ubiquitin ligase complexes, including the von Hippel-Lindau ubiquitination complex CBC(VHL). By binding to BC-box motifs it seems to link target recruitment subunits, like VHL and members of the SOCS box family, to Cullin/RBX1 modules that activate E2 ubiquitination enzymes.[5] [6] [ELOC_HUMAN] SIII, also known as elongin, is a general transcription elongation factor that increases the RNA polymerase II transcription elongation past template-encoded arresting sites. Subunit A is transcriptionally active and its transcription activity is strongly enhanced by binding to the dimeric complex of the SIII regulatory subunits B and C (elongin BC complex).[7] The elongin BC complex seems to be involved as an adapter protein in the proteasomal degradation of target proteins via different E3 ubiquitin ligase complexes, including the von Hippel-Lindau ubiquitination complex CBC(VHL). By binding to BC-box motifs it seems to link target recruitment subunits, like VHL and members of the SOCS box family, to Cullin/RBX1 modules that activate E2 ubiquitination enzymes.[8] Publication Abstract from PubMedMulti-subunit Cullin-RING E3 ligases often use repeat domain proteins as substrate-specific adaptors. Structures of these macromolecular assemblies are determined for the F-box-containing leucine-rich repeat and WD40 repeat families, but not for the suppressor of cytokine signaling (SOCS)-box-containing ankyrin repeat proteins (ASB1-18), which assemble with Elongins B and C and Cul5. We determined the crystal structures of the ternary complex of ASB9-Elongin B/C as well as the interacting N-terminal domain of Cul5 and used structural comparisons to establish a model for the complete Cul5-based E3 ligase. The structures reveal a distinct architecture of the ASB9 complex that positions the ankyrin domain coaxial to the SOCS box-Elongin B/C complex and perpendicular to other repeat protein complexes. This alternative architecture appears favorable to present the ankyrin domain substrate-binding site to the E2-ubiquitin, while also providing spacing suitable for bulky ASB9 substrates, such as the creatine kinases. The presented Cul5 structure also differs from previous models and deviates from other Cullins via a rigid-body rotation between Cullin repeats. This work highlights the adaptability of repeat domain proteins as scaffolds in substrate recognition and lays the foundation for future structure-function studies of this important E3 family. Molecular Architecture of the Ankyrin SOCS Box Family of Cul5-Dependent E3 Ubiquitin Ligases.,Muniz JR, Guo K, Kershaw NJ, Ayinampudi V, von Delft F, Babon JJ, Bullock AN J Mol Biol. 2013 Jun 25. pii: S0022-2836(13)00394-X. doi:, 10.1016/j.jmb.2013.06.015. PMID:23806657[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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Categories: Human | Arrowsmith, C H | Ayinampudi, V | Bountra, C | Bullock, A N | Delft, F von | Edwards, A M | Filippakopoulos, P | Guo, K | Keates, T | Knapp, S | Krojer, T | Muniz, J R.C | Savitsky, P | Ugochukwu, E | Vollmar, M | Weigelt, J | Yue, W W | Zhang, Y | Autoantibody | Transcription | Transcription regulation
