title: G-quartets assembly within a G-rich DNA flap. A possible event at the center of the HIV-1 genome.
abstract: Stretches of guanines can associate in vitro through Hoogsteen hydrogen bonding to form four-stranded structures. In the HIV-1 central DNA flap, generated by reverse transcriptase at the end of retrotranscription, both the two 99 nt-long overlapping (+) strands contain two adjacent tracts of guanines. This study demonstrates that oligonucleotides containing these G-clusters form highly stable G-quadruplexes of various structures in vitro, whose formation was controlled by an easy and reversible protocol using sodium hydroxide. Among these sequences, a G'2 hairpin dimer was the most stable structure adopted by the 5'-tail of the (+) downstream strand. Since the two (+) strands of the HIV-1 central DNA flap hold these G-clusters, and based on the properties of reverse branch migration in DNA flaps, constructions using HIV-1 sequences were assembled to mimic small DNA flaps where the G-clusters are neighbors. G-quartets were successfully probed in such flaps. They were induced by potassium and by a dibenzophenanthroline derivative already known to stabilize them. Such results suggest some function(s) for G-quartets associated with a DNA flap in the HIV-1 pre-integration steps, and argue for their transient formation during the processing of G-rich DNA flaps at the time of replication and/or repair.
authors.affiliation: Laboratoire de Microscopie Moléculaire et Cellulaire, CNRS UMR 8126, Institut Gustave Roussy, 94805 Villejuif, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lyonnais
authors.forename: Candide
authors.initials: C
authors.lastname: Hounsou
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Teulade-Fichou
authors.forename: Josette
authors.initials: J
authors.lastname: Jeusset
authors.forename: Eric
authors.initials: E
authors.lastname: Le Cam
authors.forename: Gilles
authors.initials: G
authors.lastname: Mirambeau
mesh_terms: D004247:DNA / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D004279:DNA, Viral / Q000737:chemistry* / Q000378:metabolism; D054856:G-Quadruplexes; D016679:Genome, Viral; D006147:Guanine / Q000737:chemistry*; D015497:HIV-1 / Q000235:genetics*; D007700:Kinetics; D008024:Ligands; D008957:Models, Genetic; D009038:Motion; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010618:Phenanthrolines / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012091:Repetitive Sequences, Nucleic Acid; D012972:Sodium Hydroxide
chemical_list: D004279:DNA, Viral; D008024:Ligands; D009838:Oligodeoxyribonucleotides; D010618:Phenanthrolines; D012972:Sodium Hydroxide; D006147:Guanine; D004247:DNA; D011188:Potassium