title: Triple helix formation with Drosophila satellite repeats. Unexpected stabilization by copper ions.
abstract: The Drosophila melanogaster (AAGAGAG)(n) satellite repeat represents up to 1.5% of the entire fly genome and may adopt non-B DNA structures such as pyrimidine triple helices. UV melting and electrophoretic mobility shift assay experiments were used to monitor the stability of intermolecular triple helices as a function of size, pH, and backbone or base modification. Three to four repeats of the heptanucleotide motif were sufficient to allow the formation of a stable complex, especially when modified TFOs were used. Unexpectedly, low concentrations (40-100 microM) of Cu(2+) were found to favor strongly pyrimidine triplex formation under near-physiological conditions. In contrast, a much higher magnesium concentration was required to stabilize these triplexes significantly, suggesting that copper may be an essential stabilizing factor for pyrimidine triplexes.
authors.affiliation: Laboratoire de Biologie Moléculaire et Cellulaire de la Différenciation, INSERM UR 309, Institut Albert Bonniot, Rond-point de la Chantourne, 38700 Grenoble, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Horn
authors.forename: Laurent
authors.initials: L
authors.lastname: Lacroix
authors.forename: Thierry
authors.initials: T
authors.lastname: Gautier
authors.forename: Masashi
authors.initials: M
authors.lastname: Takasugi
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Mergny
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lacoste
mesh_terms: D000818:Animals; D020029:Base Pairing; D002413:Cations, Divalent; D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004276:DNA, Satellite / Q000737:chemistry*; D004331:Drosophila melanogaster / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D006570:Heterochromatin / Q000737:chemistry / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D011742:Pyrimidine Nucleotides / Q000737:chemistry; D012091:Repetitive Sequences, Nucleic Acid; D014466:Ultraviolet Rays
chemical_list: D002413:Cations, Divalent; D004276:DNA, Satellite; D006570:Heterochromatin; D009841:Oligonucleotides; D011742:Pyrimidine Nucleotides; C051802:triplex DNA; D003300:Copper; D004247:DNA; D008274:Magnesium