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Critical Contribution of the MDM2 Acidic Domain to p53 Ubiquitination
- Source :
- Molecular and Cellular Biology. 23:4939-4947
- Publication Year :
- 2003
- Publisher :
- Informa UK Limited, 2003.
-
Abstract
- MDM2 is an E3 ubiquitin ligase that targets p53 for proteasomal degradation. Recent studies have shown, however, that the ring-finger domain (RFD) of MDM2, where the ubiquitin E3 ligase activity resides, is necessary but not sufficient for p53 ubiquitination, suggesting that an additional activity of MDM2 might be required. To test this possibility, we generated a series of MDM2/MDMX chimeric proteins to assess the contribution of each domain of MDM2 to the ubiquitination process. MDMX is a close structural homolog of MDM2 that nevertheless lacks the E3 ligase activity in vivo. We demonstrate here that MDMX gains self-ubiquitination activity and becomes extremely unstable upon introduction of the MDM2 RFD, indicating that the RFD is essential for self-ubiquitination. This MDMX chimeric protein, however, is unable to ubiquitinate p53 in vivo despite its E3 ligase activity and binding to p53, separating the self-ubiquitination activity of MDM2 from its ability to ubiquitinate p53. Significantly, fusion of the central acidic domain (AD) of MDM2 to the MDMX chimeric protein renders the protein fully capable of ubiquitinating p53, and p53 ubiquitination is associated with p53 degradation and nuclear export. Moreover, the AD mini protein expressed in trans can functionally rescue the AD-lacking MDM2 mutant, further supporting a critical role for the AD in MDM2-mediated p53 ubiquitination.
- Subjects :
- MDMX
Ubiquitin-Protein Ligases
Ligases
Mice
Ubiquitin
Proto-Oncogene Proteins c-mdm2
Proto-Oncogene Proteins
Animals
Nuclear protein
Nuclear export signal
Cell Growth and Development
neoplasms
Molecular Biology
Cells, Cultured
Cell Nucleus
Binding Sites
biology
Nuclear Proteins
Cell Biology
Fibroblasts
Fusion protein
Molecular biology
Recombinant Proteins
Protein Structure, Tertiary
Ubiquitin ligase
Cell biology
enzymes and coenzymes (carbohydrates)
Protein Transport
biology.protein
Mdm2
Tumor Suppressor Protein p53
Subjects
Details
- ISSN :
- 10985549
- Volume :
- 23
- Database :
- OpenAIRE
- Journal :
- Molecular and Cellular Biology
- Accession number :
- edsair.doi.dedup.....bd3f03a8291ff426f31cc59f7771b8f1