Structure of UBE2K-Ub/E3/polyUb reveals mechanisms of K48-linked Ub chain extension

Nakasone, M. A., Majorek, K. A., Gabrielsen, M. , Sibbet, G. J., Smith, B. O. and Huang, D. T. (2022) Structure of UBE2K-Ub/E3/polyUb reveals mechanisms of K48-linked Ub chain extension. Nature Chemical Biology, 18, pp. 422-431. (doi: 10.1038/s41589-021-00952-x) (PMID:35027744) (PMCID:PMC8964413)

Abstract

Ubiquitin (Ub) chain types govern distinct biological processes. K48-linked polyUb chains target substrates for proteasomal degradation, but the mechanism of Ub chain synthesis remains elusive due to the transient nature of Ub handover. Here, we present the structure of a chemically trapped complex of the E2 UBE2K covalently linked to donor Ub and acceptor K48-linked di-Ub, primed for K48-linked Ub chain synthesis by a RING E3. The structure reveals the basis for acceptor Ub recognition by UBE2K active site residues and the C-terminal Ub-associated (UBA) domain, to impart K48-linked Ub specificity and catalysis. Furthermore, the structure unveils multiple Ub-binding surfaces on the UBA domain that allow distinct binding modes for K48- and K63-linked Ub chains. This multivalent Ub-binding feature serves to recruit UBE2K to ubiquitinated substrates to overcome weak acceptor Ub affinity and thereby promote chain elongation. These findings elucidate the mechanism of processive K48-linked polyUb chain formation by UBE2K.

• Item Type: Articles
• Additional Information: This work was supported by Beatson Institute core funding from CRUK (A17196 and A31287), by Cancer Research UK (A23278/A29256) and European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 647849).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Huang, Professor Danny and Gabrielsen, Dr Mads and Sibbet, Dr Gary and Smith, Dr Brian
• Authors: Nakasone, M. A., Majorek, K. A., Gabrielsen, M., Sibbet, G. J., Smith, B. O., and Huang, D. T.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences; College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
• Journal Name: Nature Chemical Biology
• Publisher: Nature Research
• ISSN: 1552-4450
• ISSN (Online): 1552-4469
• First Published: First published in Nature Chemical Biology 18:422-431
• Publisher Policy: Reproduced under a Creative Commons Licence