title: p53 binds single-stranded DNA ends and catalyzes DNA renaturation and strand transfer.
abstract: The p53 tumor-suppressor protein has previously been shown to bind double-stranded and single-stranded DNA. We report that the p53 protein can bind single-stranded DNA ends and catalyze DNA renaturation and DNA strand transfer. Both a bacterially expressed wild-type p53 protein and a glutathione S-transferase-wild-type p53 fusion protein catalyzed renaturation of different short (25- to 76-nt) complementary single-stranded DNA fragments and promoted strand transfer between short (36-bp) duplex DNA and complementary single-stranded DNA. Mutant p53 fusion proteins carrying amino acid substitutions Glu-213, Ile-237, or Tyr-238, derived from mutant p53 genes of Burkitt lymphomas, failed to catalyze these reactions. Wild-type p53 had significantly higher binding affinity for short (36- to 76-nt) than for longer (> or = 462-nt) single-stranded DNA fragments in an electrophoretic mobility-shift assay. Moreover, electron microscopy showed that p53 preferentially binds single-stranded DNA ends. Binding of DNA ends to p53 oligomers may allow alignment of complementary strands. These findings suggest that p53 may play a direct role in the repair of DNA breaks, including the joining of complementary single-stranded DNA ends.
authors.affiliation: Department of Drug Dependence Research, Karolinska Institute, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Bakalkin
authors.forename: T
authors.initials: T
authors.lastname: Yakovleva
authors.forename: G
authors.initials: G
authors.lastname: Selivanova
authors.forename: K P
authors.initials: KP
authors.lastname: Magnusson
authors.forename: L
authors.initials: L
authors.lastname: Szekely
authors.forename: E
authors.initials: E
authors.lastname: Kiseleva
authors.forename: G
authors.initials: G
authors.lastname: Klein
authors.forename: L
authors.initials: L
authors.lastname: Terenius
authors.forename: K G
authors.initials: KG
authors.lastname: Wiman
mesh_terms: D001483:Base Sequence; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009695:Nucleic Acid Renaturation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53