title: p53 is phosphorylated in vitro and in vivo by an ultraviolet radiation-induced protein kinase characteristic of the c-Jun kinase, JNK1.
abstract: The p53 tumor suppressor protein is thought to play a major role in the defense of the cell against agents that damage DNA. In this report, we describe the identification and characterization of a protein kinase that phosphorylates mouse p53 at a single site, serine 34, a major site of phosphorylation in the cell. The protein kinase is activated strikingly following treatment of cells with ultraviolet radiation, has a native molecular weight of approximately 45,000, and can be resolved from mitogen-activated protein (MAP) kinase by chromatography on Superose 6 and DEAE-cellulose. The p53 kinase activity co-purifies with UV-activated c-Jun kinase activity on heparin-Sepharose and on a c-Jun (but not a v-Jun-) affinity column. Treatment of the partially purified kinase with CL100, a protein phosphatase that specifically dephosphorylates MAP kinase homologues, inhibits its activity. Taken together, the data suggest that this p53 kinase is likely to be activated by phosphorylation and may be a member of the stress-activated protein kinase subfamily of MAP kinases. UV irradiation of SV3T3 cells leads to increased phosphorylation of p53 at serine 34, indicating that phosphorylation of p53 by this kinase is likely to be physiological. Phosphorylation of p53 by this protein kinase may be a key event in a signal transduction mechanism that coordinately controls key nuclear proteins in response to oxidative stress or DNA damaging agents.
authors.affiliation: Biomedical Research Center, Ninewells Hospital and Medical School, University of Dundee, United Kingdom.
authors.forename: D M
authors.initials: DM
authors.lastname: Milne
authors.forename: L E
authors.initials: LE
authors.lastname: Campbell
authors.forename: D G
authors.initials: DG
authors.lastname: Campbell
authors.forename: D W
authors.initials: DW
authors.lastname: Meek
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D002461:Cell Line, Transformed; D002645:Chickens; D002846:Chromatography, Affinity; D004790:Enzyme Induction / Q000528:radiation effects; D005982:Glutathione Transferase / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014357:Trypsin; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D010748:Phosphopeptides; D016755:Proto-Oncogene Proteins c-jun; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D010768:Phosphoserine; D005982:Glutathione Transferase; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D014357:Trypsin