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Identification of a Catalytic Active but Non-Aggregating MDM2 RING Domain Variant

Authors
  • Magnussen, Helge M.
  • Huang, Danny T.
Type
Published Article
Journal
Journal of Molecular Biology
Publisher
Elsevier
Publication Date
Mar 05, 2021
Volume
433
Issue
5
Identifiers
DOI: 10.1016/j.jmb.2021.166807
PMID: 33450248
PMCID: PMC7895813
Source
PubMed Central
Keywords
Disciplines
  • Research Article
License
Unknown

Abstract

As a key regulator of the tumour suppressor protein p53, MDM2 is involved in various types of cancer and has thus been an attractive drug target. So far, small molecule design has primarily focussed on the N-terminal p53-binding domain although on-target toxicity effects have been reported. Targeting the catalytic RING domain of MDM2 resembles an alternative approach to drug MDM2 with the idea to prevent MDM2-mediated ubiquitination of p53 while retaining MDM2′s ability to bind p53. The design of RING inhibitors has been limited by the extensive aggregation tendency of the RING domain, making it challenging to undertake co-crystallization attempts with potential inhibitors. Here we compare the purification profiles of the MDM2 RING domain from several species and show that the MDM2 RING domain of other species than human is much less prone to aggregate although the overall structure of the RING domain is conserved. Through sequence comparison and mutagenesis analyses, we identify a single point mutation, G443T, which greatly enhances the dimeric fraction of human MDM2 RING domain during purification. Neither does the mutation alter the structure of the RING domain, nor does it affect E2(UbcH5B)–Ub binding and activity. Hence, MDM2-G443T facilitates studies involving binding partners that would be hampered by the low solubility of the wild-type RING domain. Furthermore, it will be valuable for the development of MDM2 RING inhibitors.

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