2AKG

Thallium form of the G-Quadruplex from Oxytricha Nova, d(G4T4G4)2

Summary for 2AKG

• Entry DOI: 10.2210/pdb2akg/pdb
• Descriptor: 5'-D(*GP*GP*GP*GP*TP*TP*TP*TP*GP*GP*GP*G)-3' (1 entity in total)
• Functional Keywords: deoxyribonucleic acid, g-quadruplex, thallium, dna
• Total number of polymer chains: 2
• Total formula weight: 7610.92

Authors

Gill, M.L.,Strobel, S.A.,Loria, J.P. (deposition date: 2005-08-03, release date: 2005-11-08, Last modification date: 2024-05-22)

Primary citation

Gill, M.L.,Strobel, S.A.,Loria, J.P.
(205)Tl NMR methods for the characterization of monovalent cation binding to nucleic acids
J.Am.Chem.Soc., 127:16723-16732, 2005

PubMed Abstract: Monovalent cations play an important role in many biological functions. The guanine rich sequence, d(G4T4G4), requires monovalent cations for formation of the G-quadruplex, d(G4T4G4)2. This requirement can be satisfied by thallium (Tl+), a potassium (K+) surrogate. To verify that the structure of d(G4T4G4)2 in the presence of Tl+ is similar to the K+-form of the G-quadruplex, the solution structure of the Tl+-form of d(G4T4G4)2 was determined. The 10 lowest energy structures have an all atom RMSD of 0.76 +/- 0.16 A. Comparison of this structure to the identical G-quadruplex formed in the presence of K+ validates the isomorphous nature of Tl+ and K+. Using a 1H-205Tl spin-echo difference experiment we show that, in the Tl+-form of d(G4T4G4)2, small scalar couplings (<1 Hz) exist between 205Tl and protons in the G-quadruplex. These data comprise the first 1H-205Tl scalar couplings observed in a biological system and have the potential to provide important constraints for structure determination. These experiments can be applied to any system in which the substituted Tl+ cations are in slow exchange with the bulk ions in solution.

PubMed: 16305263
DOI: 10.1021/ja055358f

Experimental method

SOLUTION NMR