Impact of conformational heterogeneity of OxoG lesions and their pairing partners on bypass fidelity by Y family polymerases

Structure. 2009 May 13;17(5):725-36. doi: 10.1016/j.str.2009.03.011.


7,8-Dihydro-8-oxoguanine (oxoG), the predominant oxidative DNA damage lesion, is processed differently by high-fidelity and Y-family lesion bypass polymerases. Although high-fidelity polymerases extend predominantly from an A base opposite an oxoG, the Y-family polymerases Dpo4 and human Pol eta preferentially extend from the oxoG*C base pair. We have determined crystal structures of extension Dpo4 ternary complexes with oxoG opposite C, A, G, or T and the next nascent base pair. We demonstrate that neither template backbone nor the architecture of the active site is perturbed by the oxoG(anti)*C and oxoG*A pairs. However, the latter manifest conformational heterogeneity, adopting both oxoG(syn)*A(anti) and oxoG(anti)*A(syn) alignment. Hence, the observed reduced primer extension from the dynamically flexible 3'-terminal primer base A is explained. Because of homology between Dpo4 and Pol eta, such a dynamic screening mechanism might be utilized by Dpo4 and Pol eta to regulate error-free versus error-prone bypass of oxoG and other lesions.

Publication types

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

MeSH terms

  • Base Pairing
  • Base Sequence
  • Binding Sites
  • Crystallography, X-Ray
  • DNA / chemistry
  • DNA Damage
  • DNA Polymerase beta / chemistry*
  • DNA Polymerase beta / metabolism
  • DNA Repair
  • Guanine / analogs & derivatives*
  • Guanine / chemistry
  • Guanine / metabolism
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Protein Conformation


  • 7,8-dihydro-8-oxoguanine
  • Guanine
  • DNA
  • DNA Polymerase beta