title: Crystallization and characterization of the thallium form of the Oxytricha nova G-quadruplex.
abstract: The crystal structure of the Tl+ form of the G-quadruplex formed from the Oxytricha nova telomere sequence, d(G4T4G4), has been solved to 1.55 A. This G-quadruplex contains five Tl+ ions, three of which are interspersed between adjacent G-quartet planes and one in each of the two thymine loops. The structure displays a high degree of similarity to the K+ crystal structure [Haider et al. (2002), J. Mol. Biol., 320, 189-200], including the number and location of the monovalent cation binding sites. The highly isomorphic nature of the two structures, which contain such a large number of monovalent binding sites (relative to nucleic acid content), verifies the ability of Tl+ to mimic K+ in nucleic acids. Information from this report confirms and extends the assignment of 205Tl resonances from a previous report [Gill et al. (2005), J. Am. Chem. Soc., 127, 16 723-16 732] where 205Tl NMR was used to study monovalent cation binding to this G-quadruplex. The assignment of these resonances provides evidence for the occurrence of conformational dynamics in the thymine loop region that is in slow exchange on the 205Tl timescale.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Gill
authors.forename: Scott A
authors.initials: SA
authors.lastname: Strobel
authors.forename: J Patrick
authors.initials: JP
authors.lastname: Loria
mesh_terms: D000818:Animals; D001665:Binding Sites; D002414:Cations, Monovalent / Q000737:chemistry; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D016054:DNA, Protozoan / Q000737:chemistry*; D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry*; D006860:Hydrogen Bonding; D007554:Isotopes; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D016813:Oxytricha / Q000235:genetics*; D016615:Telomere / Q000737:chemistry*; D013793:Thallium / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D002414:Cations, Monovalent; D016054:DNA, Protozoan; D007554:Isotopes; D014867:Water; D006147:Guanine; D004247:DNA; D013793:Thallium