title: Sequence-targeted cleavage of single- and double-stranded DNA by oligothymidylates covalently linked to 1,10-phenanthroline.
abstract: The nuclease activity of 1,10-phenanthroline copper ion was targeted to a specific sequence by attachment of the ligand to the 5' or 3' end of octathymidylates. An acridine derivative was also attached to the other end of the oligothymidylate-phenanthroline conjugate. The duplex formed by the oligothymidylate with its complementary sequence was stabilized by intercalation of the acridine derivative. The reaction induced by 3-mercaptopropionic acid led to a very localized cleavage of a 27-nucleotide-long DNA fragment containing a (dA)8 sequence. At high NaCl concentration or in the presence of spermine, cleavage of the single-stranded 27-mer fragment occurred on both sides of the target sequence. This was ascribed to the formation of a triple helix involving two 1,10-phenanthroline-octathymidylate strands that adopt an antiparallel orientation with respect to each other. When a 27-mer duplex was used as a substrate, cleavage sites were observed on both strands. The location of the cleavage sites led us to conclude that the octathymidylate was bound to the (dA)8.(dT)8 sequence in a parallel orientation with respect to the (dA)8-containing strand. This result reflects the ability of thymine to form two hydrogen bonds with an adenine already engaged in a Watson-Crick base pair. This study shows that it is possible to design DNA-binding oligodeoxynucleotides that could selectively recognize and cleave polypurine-polypyrimidine sequences in double-stranded DNA.
authors.affiliation: Laboratoire de Biophysique, Muséum National d'Histoire Naturelle, Institut National de la Santé et de la Recherche Medicale U. 201, Paris, France.
authors.forename: J C
authors.initials: JC
authors.lastname: François
authors.forename: T
authors.initials: T
authors.lastname: Saison-Behmoaras
authors.forename: M
authors.initials: M
authors.lastname: Chassignol
authors.forename: N T
authors.initials: NT
authors.lastname: Thuong
authors.forename: C
authors.initials: C
authors.lastname: Helene
mesh_terms: D001483:Base Sequence; D004247:DNA; D004277:DNA, Single-Stranded; D007202:Indicators and Reagents; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis; D009994:Osmolar Concentration; D010618:Phenanthrolines
chemical_list: D004277:DNA, Single-Stranded; D007202:Indicators and Reagents; D009838:Oligodeoxyribonucleotides; D010618:Phenanthrolines; C027903:oligo (dT); C014741:bis(1,10-phenanthroline)copper(2+) ion; D004247:DNA