title: Human replication protein A unfolds telomeric G-quadruplexes.
abstract: G-quadruplex structures inhibit telomerase activity and must be disrupted for telomere elongation during S phase. It has been suggested that the replication protein A (RPA) could unwind and maintain single-stranded DNA in a state amenable to the binding of telomeric components. We show here that under near-physiological in vitro conditions, human RPA is able to bind and unfold G-quadruplex structures formed from a 21mer human telomeric sequence. Analyses by native gel electrophoresis, cross-linking and fluorescence resonance energy transfer indicate the formation of both 1:1 and 2:1 complexes in which G-quadruplexes are unfolded. In addition, quadruplex opening by hRPA is much faster than observed with the complementary DNA, demonstrating that this protein efficiently unfolds G-quartets. A two-step mechanism accounting for the binding of hRPA to G-quadruplexes is proposed. These data point to the involvement of hRPA in regulation of telomere maintenance.
authors.affiliation: Institut Jacques Monod, CNRS-ParisVI-ParisVII-UMR 7592, 2 place Jussieu, 75251 Paris cedex 05, France.
authors.forename: Tonatiuh Romero
authors.initials: TR
authors.lastname: Salas
authors.forename: Irina
authors.initials: I
authors.lastname: Petruseva
authors.forename: Olga
authors.initials: O
authors.lastname: Lavrik
authors.forename: Anne
authors.initials: A
authors.lastname: Bourdoncle
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Mergny
authors.forename: Alain
authors.initials: A
authors.lastname: Favre
authors.forename: Carole
authors.initials: C
authors.lastname: Saintomé
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry*; D006801:Humans; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D051716:Replication Protein A / Q000378:metabolism*; D016615:Telomere / Q000737:chemistry*
chemical_list: D009841:Oligonucleotides; D051716:Replication Protein A; D006147:Guanine; D004247:DNA