title: Binding polarity of RPA to telomeric sequences and influence of G-quadruplex stability.
abstract: Replication protein A (RPA) is a single-stranded DNA binding protein that plays an essential role in telomere maintenance. RPA binds to and unfolds G-quadruplex (G4) structures formed in telomeric DNA, thus facilitating lagging strand DNA replication and telomerase activity. To investigate the effect of G4 stability on the interactions with human RPA (hRPA), we used a combination of biochemical and biophysical approaches. Our data revealed an inverse relationship between G4 stability and ability of hRPA to bind to telomeric DNA; notably small G4 ligands that enhance G4 stability strongly impaired G4 unfolding by hRPA. To gain more insight into the mechanism of binding and unfolding of telomeric G4 structures by RPA, we carried out photo-crosslinking experiments to elucidate the spatial arrangement of the RPA subunits along the DNA strands. Our results showed that RPA1 and RPA2 are arranged from 5' to 3' along the unfolded telomeric G4, as already described for unstructured single-stranded DNA, while no contact is possible with RPA3 on this short oligonucleotide. In addition, these data are compatible with a 5' to 3' directionality in G4 unfolding by hRPA.
authors.affiliation: Structure des Acides Nucléiques, Télomères et Evolution, Inserm U1154, CNRS UMR 7196, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris cedex 05, France; Université Pierre et Marie Curie, 4 place Jussieu, 75005 Paris, France.
authors.forename: Layal
authors.initials: L
authors.lastname: Safa
authors.affiliation: Structure des Acides Nucléiques, Télomères et Evolution, Inserm U1154, CNRS UMR 7196, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris cedex 05, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Delagoutte
authors.affiliation: Novosibirsk Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Science, 630090 Novosibirsk, Russia.
authors.forename: Irina
authors.initials: I
authors.lastname: Petruseva
authors.affiliation: Structure des Acides Nucléiques, Télomères et Evolution, Inserm U1154, CNRS UMR 7196, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris cedex 05, France.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Alberti
authors.affiliation: Novosibirsk Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Science, 630090 Novosibirsk, Russia.
authors.forename: Olga
authors.initials: O
authors.lastname: Lavrik
authors.affiliation: Structure des Acides Nucléiques, Télomères et Evolution, Inserm U1154, CNRS UMR 7196, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris cedex 05, France. Electronic address: riou@mnhn.fr.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Riou
authors.affiliation: Structure des Acides Nucléiques, Télomères et Evolution, Inserm U1154, CNRS UMR 7196, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris cedex 05, France; Université Pierre et Marie Curie, 4 place Jussieu, 75005 Paris, France. Electronic address: saintome@mnhn.fr.
authors.forename: Carole
authors.initials: C
authors.lastname: Saintomé
mesh_terms: D001483:Base Sequence; D054856:G-Quadruplexes; D006801:Humans; D008024:Ligands; D011485:Protein Binding; D051716:Replication Protein A / Q000378:metabolism*; D013379:Substrate Specificity; D016615:Telomere / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D008024:Ligands; D051716:Replication Protein A
keywords: G-quadruplexes; G4 ligands; Photo-crosslinking; Telomeres; hRPA