Transient Hoogsteen base pairs in canonical duplex DNA

Nature. 2011 Feb 24;470(7335):498-502. doi: 10.1038/nature09775. Epub 2011 Jan 26.

Abstract

Sequence-directed variations in the canonical DNA double helix structure that retain Watson-Crick base-pairing have important roles in DNA recognition, topology and nucleosome positioning. By using nuclear magnetic resonance relaxation dispersion spectroscopy in concert with steered molecular dynamics simulations, we have observed transient sequence-specific excursions away from Watson-Crick base-pairing at CA and TA steps inside canonical duplex DNA towards low-populated and short-lived A•T and G•C Hoogsteen base pairs. The observation of Hoogsteen base pairs in DNA duplexes specifically bound to transcription factors and in damaged DNA sites implies that the DNA double helix intrinsically codes for excited state Hoogsteen base pairs as a means of expanding its structural complexity beyond that which can be achieved based on Watson-Crick base-pairing. The methods presented here provide a new route for characterizing transient low-populated nucleic acid structures, which we predict will be abundant in the genome and constitute a second transient layer of the genetic code.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Base Pairing*
  • Base Sequence
  • DNA / chemistry*
  • DNA / metabolism
  • Genetic Code
  • Hydrogen Bonding
  • Kinetics
  • Magnetic Resonance Spectroscopy
  • Molecular Dynamics Simulation
  • Quantum Theory
  • Thermodynamics

Substances

  • DNA