title: The high kinetic stability of a G-quadruplex limits hnRNP F qRRM3 binding to G-tract RNA.
abstract: The RNA binding protein heterogeneous nuclear ribonucleoprotein (hnRNP) F is involved in telomeres maintenance and pre-mRNA processing, such as alternative splicing and polyadenylation. It specifically recognizes RNA containing three consecutive guanines (G-tracts) that have the potential to assemble into G-quadruplexes. We have proposed recently that hnRNP F could regulate alternative splicing by remodeling RNA structures, such as G-quadruplexes. However, the exact mechanism of hnRNP F binding to such RNA sequences remains unknown. Here, we have studied the binding of the third RNA binding domain of hnRNP F [quasi-RNA recognition motif 3 (qRRM3)] to G-tract RNA using isothermal titration calorimetry, circular dichroism and nuclear magnetic resonance spectroscopy. Our results show that qRRM3 binds specifically exclusively to single-stranded G-tracts (ssRNA), in contrast to previous reports stating that the G-quadruplex was recognized as well. Furthermore, we demonstrate that the pre-existent ssRNA/G-quadruplex equilibrium slows down the formation of the protein-ssRNA complex. Based on in vitro transcription assays, we show that the rate of the protein-RNA complex formation is faster than that of the G-quadruplex. We propose a model according to which hnRNP F could bind RNA co-transcriptionally and prevents G-quadruplex formation.
authors.affiliation: Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Brighton
authors.initials: B
authors.lastname: Samatanga
authors.forename: Cyril
authors.initials: C
authors.lastname: Dominguez
authors.forename: Ilian
authors.initials: I
authors.lastname: Jelesarov
authors.forename: Frédéric H-T
authors.initials: FH
authors.lastname: Allain
mesh_terms: D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry*; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry* / Q000378:metabolism; D016615:Telomere / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D006147:Guanine; D012313:RNA