title: Four domains of p300 each bind tightly to a sequence spanning both transactivation subdomains of p53.
abstract: The transcriptional coactivator p300 binds to and mediates the transcriptional functions of the tetrameric tumor suppressor p53. Both proteins consist of independently folded domains linked by intrinsically disordered sequences. A well studied short sequence of the p53 transactivation domain, p53(15-29), binds weakly to four folded domains of p300 [Taz1/cysteine-histidine-rich region 1 (CH1), Kix, Taz2/CH3, IBiD], with dissociation constants (K(D)) in the 100 muM region. However, we found that a longer N-terminal transactivation domain construct p53(1-57) bound tightly to each p300 domain. Taz2/CH3 had the greatest affinity (K(D) = 27 nM) and competes with the N-terminal domain of Mdm2 for the p53 N terminus. p300 thus can protect the N terminus of p53 against the binding of other proteins. Mutations of p53 that abrogate transactivation (L22Q/W23S, W53Q/F54S) greatly weakened binding to each p300 domain, linking phenotypic defects to weakened coactivator binding. We propose a complex between tetrameric p53 and p300 in which four domains of p300 wrap around the four transactivation domains of p53.
authors: MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road, Cambridge, UK.
authors: Daniel P
authors: DP
authors: Teufel
authors: Stefan M
authors: SM
authors: Freund
authors: Mark
authors: M
authors: Bycroft
authors: Alan R
authors: AR
authors: Fersht
mesh_terms: D000595:Amino Acid Sequence; D001667:Binding, Competitive; D050881:E1A-Associated p300 Protein / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051736:Proto-Oncogene Proteins c-mdm2 / Q000737:chemistry / Q000378:metabolism; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D050505:Mutant Proteins; D010455:Peptides; D016159:Tumor Suppressor Protein p53; D050881:E1A-Associated p300 Protein; C494360:EP300 protein, human; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2