A novel chair-type G-quadruplex formed by a Bombyx mori telomeric sequence

Nucleic Acids Res. 2009 Feb;37(3):931-8. doi: 10.1093/nar/gkn990. Epub 2008 Dec 22.

Abstract

Recently, the human telomeric d[TAGGG(TTAGGG)(3)] sequence has been shown to form in K(+) solution an intramolecular (3+1) G-quadruplex structure, whose G-tetrad core contains three strands oriented in one direction and the fourth in the opposite direction. Here we present a study on the structure of the Bombyx mori telomeric d[TAGG(TTAGG)(3)] sequence, which differs from the human counterpart only by one G deletion in each repeat. We found that this sequence adopted multiple G-quadruplex structures in K(+) solution. We have favored a major G-quadruplex form by a judicious U-for-T substitution in the sequence and determined the folding topology of this form. We showed by NMR that this was a new chair-type intramolecular G-quadruplex which involved a two-layer antiparallel G-tetrad core and three edgewise loops. Our result highlights the effect of G-tract length on the folding topology of G-quadruplexes, but also poses the question of whether a similar chair-type G-quadruplex fold exists in the human telomeric sequences.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Bombyx / genetics*
  • Circular Dichroism
  • G-Quadruplexes*
  • Models, Molecular
  • Motion
  • Nuclear Magnetic Resonance, Biomolecular
  • Spectrophotometry, Ultraviolet
  • Telomere / chemistry*