title: Interaction between the transactivation domain of p53 and PC4 exemplifies acidic activation domains as single-stranded DNA mimics.
abstract: The tumor suppressor p53 regulates cell cycle arrest and apoptosis by transactivating several genes that are critical for these processes. The transcriptional activity of p53 is often regulated by post-translational modifications and its interactions with various transcriptional coactivators. Here we report a physical interaction between the N-terminal transactivation domain (TAD) of p53 and the C-terminal DNA-binding domain of positive cofactor 4 (PC4(CTD)). Using NMR spectroscopy, we showed that residues 35-57 (TAD2) interact with PC4. (15)N,(1)H HSQC and fluorescence competition experiments indicated that TAD binds to the DNA-binding site of PC4. Hepta-phosphorylation of the TAD peptide increased its binding affinity. Computer modeling of the p53N-PC4 complex revealed several important interactions that are reminiscent of those in the single-stranded DNA-PC4 complex. The ubiquitous nature of the acidic transactivation domain of p53 in mediating interactions with several transcription cofactors is also manifested as a DNA mimetic.
authors.affiliation: MRC Centre for Protein Engineering, Cambridge, United Kingdom.
authors.forename: Sridharan
authors.initials: S
authors.lastname: Rajagopalan
authors.forename: Antonina
authors.initials: A
authors.lastname: Andreeva
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Teufel
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Freund
authors.forename: Alan R
authors.initials: AR
authors.lastname: Fersht
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence / Q000379:methods; D014157:Transcription Factors / Q000737:chemistry*; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C509201:SUB1 protein, human; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D004247:DNA