An essential function of the extreme C-terminus of MDM2 can be provided by MDMX.
MDM2 (HDM2) is a ubiquitin ligase that can target the p53 tumor suppressor protein for degradation. The RING domain is essential for the E3 activity of MDM2, and we show here that the extreme C-terminal tail of MDM2 is also critical for efficient E3 activity. Loss of E3 function in MDM2 mutants deleted of the C-terminal tail correlated with a failure of these mutants to oligomerize with MDM2, or with the related protein MDMX (HDMX). However, MDM2 containing point mutations within the C-terminus that inactivated E3 function retained the ability to oligomerize with the wild-type MDM2 RING domain and MDMX, and our results indicate that oligomers containing both wild-type MDM2 and a C-terminal mutant protein retain E3 function both in auto-degradation and degradation of p53. Interestingly, the E3 activity of C-terminal point mutants of MDM2 can also be supported by interaction with wild-type MDMX, suggesting that MDMX can directly contribute to E3 function.
Uldrijan
Stjepan
S
The Beatson Institute for Cancer Research, Glasgow, UK.
Pannekoek
Willem-Jan
WJ
Vousden
Karen H
KH
D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000502:physiology*; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000502:physiology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000737:chemistry* / Q000502:physiology*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry
D018797:Cell Cycle Proteins; C482775:MDM4 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D044767:Ubiquitin-Protein Ligases