Serine15 phosphorylation stimulates p53 transactivation but does not directly influence interaction with HDM2.

The p53 tumour suppressor protein is a labile transcription factor that is activated and stabilized in response to a wide range of cellular stresses, through a mechanism involving disruption of its interaction with MDM2, a negative regulatory partner. Induction of p53 by DNA damage additionally involves a series of phosphorylation ...
and acetylation modifications, some of which are thought to regulate MDM2 binding. Here we report the effects of introducing mutations at several known or putative N-terminal phosphorylation sites on the transactivation function of p53. These studies highlight phosphorylation of Ser15, a key phosphorylation target during the p53 activation process, as being critical for p53-dependent transactivation. Biochemical data indicate that the mechanism by which phosphorylation of Ser15 stimulates p53-dependent transactivation occurs through increased binding to the p300 coactivator protein. The data also indicate that Ser15-dependent regulation of transactivation is independent of any involvement in modulating MDM2 binding, and that Ser15 phosphorylation alone is not sufficient to block the p53-MDM2 interaction.
Mesh Terms:
Amino Acid Substitution, Cell Line, DNA-Activated Protein Kinase, DNA-Binding Proteins, Genes, Reporter, Humans, Mutagenesis, Site-Directed, Nuclear Proteins, Phosphoserine, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-mdm2, Recombinant Fusion Proteins, Recombinant Proteins, Serine, Transcriptional Activation, Transfection, Tumor Suppressor Protein p53
Date: Dec. 15, 1999
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