DSSR-derived G-quadruplex features in PDB entry 2m1g
- Parallel human telomeric quadruplex containing 2'f-ana substitutions
- Martin-Pintado, N., Yahyaee-Anzahaee, M., Deleavey, G.F., Portella, G., Orozco, M., Damha, M.J., Gonzalez, C.: (2013) "Dramatic effect of furanose c2' substitution on structure and stability: directing the folding of the human telomeric quadruplex with a single fluorine atom." J.Am.Chem.Soc., 135, 5344-5347.
- Human telomeric DNA quadruplexes can adopt different conformations in solution. We have found that arabinose, 2'F-arabinose, and ribose substitutions stabilize the propeller parallel G-quadruplex form over competing conformers, allowing NMR structural determination of this particularly significant nucleic acid structure. 2'F-arabinose substitution provides the greatest stabilization as a result of electrostatic (F-CH---O4') and pseudo-hydrogen-bond (F---H8) stabilizing interactions. In contrast, 2'F-rG substitution provokes a dramatic destabilization of the quadruplex structure due to unfavorable electrostatic repulsion between the phosphate and the 2'-F.
- G4 notes
- 3 G-tetrads, 1 G4 helix, 1 G4 stem · parallel(4+0), UUUU
1 glyco-bond=---- groove=---- planarity=0.336 type=other nts=4 GgGg A.DG3,A.GFL9,B.DG15,B.GFL21 2 glyco-bond=---- groove=---- planarity=0.143 type=planar nts=4 GGGG A.DG4,A.DG10,B.DG16,B.DG22 3 glyco-bond=---- groove=---- planarity=0.367 type=bowl nts=4 GGGG A.DG5,A.DG11,B.DG17,B.DG23
In DSSR, a G4-helix is defined by stacking interactions of G-tetrads, regardless of backbone connectivity, and may contain more than one G4-stem.
Helix#1, 3 G-tetrad layers, inter-molecular, with 1 stem
In DSSR, a G4-stem is defined as a G4-helix with backbone connectivity. Bulges are also allowed along each of the four strands.