title: Serine15 phosphorylation stimulates p53 transactivation but does not directly influence interaction with HDM2.
abstract: 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.
authors.affiliation: Biomedical Research Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: N
authors.initials: N
authors.lastname: Dumaz
authors.forename: D W
authors.initials: DW
authors.lastname: Meek
mesh_terms: D019943:Amino Acid Substitution; D002460:Cell Line; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D017930:Genes, Reporter; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012694:Serine; D015533:Transcriptional Activation; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D010768:Phosphoserine; D012694:Serine; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases