title: Latent and active p53 are identical in conformation.
abstract: p53 is a nuclear phosphoprotein that regulates cellular fate after genotoxic stress through its role as a transcriptional regulator of genes involved in cell cycle control and apoptosis. The C-terminal region of p53 is known to negatively regulate sequence specific DNA-binding of p53; modifications to the C-terminus relieve this inhibition. Two models have been proposed to explain this latency: (i) an allosteric model in which the C-terminal domain interacts with another domain of p53 or (ii) a competitive model in which the C-terminal and the core domains compete for DNA binding. We have characterized latent and active forms of dimeric p53 using gel mobility shift assays and NMR spectroscopy. We show on the basis of chemical shifts that dimeric p53 both containing and lacking the C-terminal domain are identical in conformation and that the C-terminus does not interact with other p53 domains. Similarly, NMR spectra of isolated core and tetramerization domains confirm a modular p53 architecture. The data presented here rule out an allosteric model for the regulation of p53.
authors.affiliation: Ontario Cancer Institute, and Department of Medical Biophysics, University of Toronto, 610 University Ave., Toronto, Ontario M5G 2M9, Canada. Ayeda@uhnres.utoronto.ca
authors.forename: A
authors.initials: A
authors.lastname: Ayed
authors.forename: F A
authors.initials: FA
authors.lastname: Mulder
authors.forename: G S
authors.initials: GS
authors.lastname: Yi
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.forename: L E
authors.initials: LE
authors.lastname: Kay
authors.forename: C H
authors.initials: CH
authors.lastname: Arrowsmith
mesh_terms: D000494:Allosteric Regulation; D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D006801:Humans; D008954:Models, Biological; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D016159:Tumor Suppressor Protein p53; D004247:DNA