title: Short loop length and high thermal stability determine genomic instability induced by G-quadruplex-forming minisatellites.
abstract: G-quadruplexes (G4) are polymorphic four-stranded structures formed by certain G-rich nucleic acids, with various biological roles. However, structural features dictating their formation and/or function in vivo are unknown. In S. cerevisiae, the pathological persistency of G4 within the CEB1 minisatellite induces its rearrangement during leading-strand replication. We now show that several other G4-forming sequences remain stable. Extensive mutagenesis of the CEB25 minisatellite motif reveals that only variants with very short (≤ 4 nt) G4 loops preferentially containing pyrimidine bases trigger genomic instability. Parallel biophysical analyses demonstrate that shortening loop length does not change the monomorphic G4 structure of CEB25 variants but drastically increases its thermal stability, in correlation with the in vivo instability. Finally, bioinformatics analyses reveal that the threat for genomic stability posed by G4 bearing short pyrimidine loops is conserved in C. elegans and humans. This work provides a framework explanation for the heterogeneous instability behavior of G4-forming sequences in vivo, highlights the importance of structure thermal stability, and questions the prevailing assumption that G4 structures with short or longer loops are as likely to form in vivo.
authors.affiliation: Institut Curie, Centre de Recherche, UMR3244 CNRS Université Pierre et Marie Curie, Paris Cedex 05, France.
authors.forename: Aurèle
authors.initials: A
authors.lastname: Piazza
authors.affiliation: School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
authors.forename: Michael
authors.initials: M
authors.lastname: Adrian
authors.affiliation: Institut Curie, Centre de Recherche, UMR3244 CNRS Université Pierre et Marie Curie, Paris Cedex 05, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Samazan
authors.affiliation: School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore.
authors.forename: Brahim
authors.initials: B
authors.lastname: Heddi
authors.affiliation: Institut Curie, Centre de Recherche, UMR 176 CNRS Université Paris-Sud, Orsay, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Hamon
authors.affiliation: Institut Curie, Centre de Recherche, UMR3244 CNRS Université Pierre et Marie Curie, Paris Cedex 05, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Serero
authors.affiliation: Institut Curie, Centre de Recherche, UMR3244 CNRS Université Pierre et Marie Curie, Paris Cedex 05, France.
authors.forename: Judith
authors.initials: J
authors.lastname: Lopes
authors.affiliation: Institut Curie, Centre de Recherche, UMR 176 CNRS Université Paris-Sud, Orsay, France.
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Teulade-Fichou
authors.affiliation: School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore PhanTuan@ntu.edu.sg alain.nicolas@curie.fr.
authors.forename: Anh Tuân
authors.initials: AT
authors.lastname: Phan
authors.affiliation: Institut Curie, Centre de Recherche, UMR3244 CNRS Université Pierre et Marie Curie, Paris Cedex 05, France PhanTuan@ntu.edu.sg alain.nicolas@curie.fr.
authors.forename: Alain
authors.initials: A
authors.lastname: Nicolas
mesh_terms: D002942:Circular Dichroism; D019295:Computational Biology; D031541:Fluorescence Resonance Energy Transfer; D054856:G-Quadruplexes; D005818:Genetic Engineering; D042822:Genomic Instability / Q000235:genetics*; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D018598:Minisatellite Repeats / Q000235:genetics*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000235:genetics; D016133:Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae
chemical_list: D009841:Oligonucleotides
keywords: G‐quadruplex; Phen‐DC3; Pif1; genomic instability; minisatellite