Nucleic Acids Research Advance Access originally published online on August 31, 2006
Nucleic Acids Research 2006 34(16):4506-4514; doi:10.1093/nar/gkl616
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Nucleic Acids Research, 2006, Vol. 34, No. 16 4506-4514
© 2006 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Structural Biology |
Crystallization and characterization of the thallium form of the Oxytricha nova G-quadruplex
1 Department of Molecular Biophysics and Biochemistry, Yale University New Haven, CT 06520, USA 2 Department of Chemistry, Yale University New Haven, CT 06520, USA
*To whom correspondence should be addressed. Tel: +1 203 436 4847; Fax: +1 203 432 6144; Email: patrick.loria{at}yale.edu
*Correspondence may also be addressed to Scott A. Strobel. Tel: +1 203 432 9772; Fax: +1 203 432 5767; Email: scott.strobel{at}yale.edu
Received June 20, 2006. Revised August 4, 2006. Accepted August 4, 2006.
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 Å. 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.