title: The single-stranded DNA end binding site of p53 coincides with the C-terminal regulatory region.
abstract: p53 is a transcription factor that binds double-stranded (ds) DNA in a sequence-specific manner. In addition, p53 can bind the ends of single-stranded (ss) DNA. We previously demonstrated that ssDNA oligonucleotides interact with the C-terminal domain of p53 and stimulate binding to internal segments of long ssDNA by the p53 core domain. Here we show that the p53 C-terminal domain can recognize staggered ss ends of dsDNA. We have mapped the binding site for ssDNA ends to residues 361-382 in human p53 using a p53 deletion mutant (p53-delta 30) lacking the 30 C-terminal amino acid residues and a series of 22mer peptides. The binding site for DNA ends coincides with a region previously implicated in regulation of sequence-specific DNA binding by the core domain. The interaction of the C-terminal regulatory domain with the ends of ssDNA or with the protruding ends of dsDNA stimulates both sequence-specific and non-specific DNA binding via the core domain. Electron microscopy demonstrated the simultaneous binding of p53 to dsDNA and a ssDNA end. These results suggest a model in which interaction of the p53 C-terminal tail with DNA ends generated after DNA damage causes activation of sequence-specific p53 DNA binding in vivo and may thus provide a molecular link between DNA damage and p53-mediated growth arrest and apoptosis.
authors.affiliation: Department of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Selivanova
authors.forename: V
authors.initials: V
authors.lastname: Iotsova
authors.forename: E
authors.initials: E
authors.lastname: Kiseleva
authors.forename: M
authors.initials: M
authors.lastname: Ström
authors.forename: G
authors.initials: G
authors.lastname: Bakalkin
authors.forename: R C
authors.initials: RC
authors.lastname: Grafström
authors.forename: K G
authors.initials: KG
authors.lastname: Wiman
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002874:Chromosome Mapping; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism; D004252:DNA Mutational Analysis; D004277:DNA, Single-Stranded / Q000378:metabolism* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D006801:Humans; D008969:Molecular Sequence Data; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D004277:DNA, Single-Stranded; D016159:Tumor Suppressor Protein p53; D004247:DNA