title: Single-stranded DNA mimicry in the p53 transactivation domain interaction with replication protein A.
abstract: One of many protein-protein interactions modulated upon DNA damage is that of the single-stranded DNA-binding protein, replication protein A (RPA), with the p53 tumor suppressor. Here we report the crystal structure of RPA residues 1-120 (RPA70N) bound to the N-terminal transactivation domain of p53 (residues 37-57; p53N) and, by using NMR spectroscopy, characterize two mechanisms by which the RPA/p53 interaction can be modulated. RPA70N forms an oligonucleotide/oligosaccharide-binding fold, similar to that previously observed for the ssDNA-binding domains of RPA. In contrast, the N-terminal p53 transactivation domain is largely disordered in solution, but residues 37-57 fold into two amphipathic helices, H1 and H2, upon binding with RPA70N. The H2 helix of p53 structurally mimics the binding of ssDNA to the oligonucleotide/oligosaccharide-binding fold. NMR experiments confirmed that both ssDNA and an acidic peptide mimicking a phosphorylated form of RPA32N can independently compete the acidic p53N out of the binding site. Taken together, our data suggest a mechanism for DNA damage signaling that can explain a threshold response to DNA damage.
authors.affiliation: Banting and Best Department of Medical Research & Department of Medical Genetics and Microbiology, University of Toronto, 112 College Street, Toronto, Ontario, Canada M5G 1L6.
authors.forename: Elena
authors.initials: E
authors.lastname: Bochkareva
authors.forename: Lilia
authors.initials: L
authors.lastname: Kaustov
authors.forename: Ayeda
authors.initials: A
authors.lastname: Ayed
authors.forename: Gwan-Su
authors.initials: GS
authors.lastname: Yi
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Antonio
authors.initials: A
authors.lastname: Pineda-Lucena
authors.forename: Jack C C
authors.initials: JC
authors.lastname: Liao
authors.forename: Andrei L
authors.initials: AL
authors.lastname: Okorokov
authors.forename: Jo
authors.initials: J
authors.lastname: Milner
authors.forename: Cheryl H
authors.initials: CH
authors.lastname: Arrowsmith
authors.forename: Alexey
authors.initials: A
authors.lastname: Bochkarev
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D051716:Replication Protein A / Q000737:chemistry* / Q000378:metabolism; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry*
chemical_list: D004277:DNA, Single-Stranded; C497167:RPA1 protein, human; D051716:Replication Protein A; D016159:Tumor Suppressor Protein p53