title: Interaction of human DNA topoisomerase I with G-quartet structures.
abstract: Because of their role in the control of the topological state of DNA, topoisomerases are ubiquitous and vital enzymes, which participate in nearly all events related to DNA metabolism including replication and transcription. We show here that human topoisomerase I (Topo I) plays an unexpected role of 'molecular matchmaker' for G-quartet formation. G-quadruplexes are multi-stranded structures held together by square planes of four guanines ('G-quartets') interacting by forming Hoogsteen hydrogen bonds. Topo I is able to promote the formation of four-stranded intermolecular DNA structures when added to single-stranded DNA containing a stretch of at least five guanines. We provide evidence that these complexes are parallel G-quartet structures, mediated by tetrads of hydrogen-bonded guanine. In addition, Topo I binds specifically to pre-formed parallel and anti-parallel G4-DNA.
authors: Laboratoire de Biophysique, Muséum National d'Histoire Naturelle CNRS UMR 8646, INSERM U201, 43 rue Cuvier, 75231 Paris cedex 05, France.
authors: P B
authors: PB
authors: Arimondo
authors: J F
authors: JF
authors: Riou
authors: J L
authors: JL
authors: Mergny
authors: J
authors: J
authors: Tazi
authors: J S
authors: JS
authors: Sun
authors: T
authors: T
authors: Garestier
authors: C
authors: C
authors: Hélène
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015342:DNA Probes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D006147:Guanine / Q000737:chemistry / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding
chemical_list: D015342:DNA Probes; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D006147:Guanine; D004247:DNA; D004264:DNA Topoisomerases, Type I