Solution structure of a unique G-quadruplex scaffold adopted by a guanosine-rich human intronic sequence

Structure. 2010 Jan 13;18(1):73-82. doi: 10.1016/j.str.2009.10.015.


We report on the solution structure of an unprecedented intramolecular G-quadruplex formed by the guanosine-rich human chl1 intronic d(G(3)-N-G(4)-N(2)-G(4)-N-G(3)-N) 19-mer sequence in K(+)-containing solution. This G-quadruplex, composed of three stacked G-tetrads containing four syn guanines, represents a new folding topology with two unique conformational features. The first guanosine is positioned within the central G-tetrad, in contrast to all previous structures of unimolecular G-quadruplexes, where the first guanosine is part of an outermost G-tetrad. In addition, a V-shaped loop, spanning three G-tetrad planes, contains no bridging nucleotides. The G-quadruplex scaffold is stabilized by a T*G*A triple stacked over the G-tetrad at one end and an unpaired guanosine stacked over the G-tetrad at the other end. Finally, the chl1 intronic DNA G-quadruplex scaffold contains a guanosine base intercalated between an extended G-G step, a feature observed in common with the catalytic site of group I introns. This unique structural scaffold provides a highly specific platform for the future design of ligands specifically targeted to intronic G-quadruplex platforms.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Base Sequence
  • Catalytic Domain
  • G-Quadruplexes*
  • Guanosine / chemistry*
  • Humans
  • Introns*
  • Models, Molecular
  • Nuclear Magnetic Resonance, Biomolecular
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / genetics
  • Tumor Suppressor Proteins / chemistry*
  • Tumor Suppressor Proteins / genetics


  • Nuclear Proteins
  • Tumor Suppressor Proteins
  • Guanosine