Mechanisms by which herpes simplex virus DNA polymerase limits translesion synthesis through abasic sites

DNA Repair (Amst). 2008 Jan 1;7(1):95-107. doi: 10.1016/j.dnarep.2007.08.001. Epub 2007 Sep 27.


Results suggest a high probability that abasic (AP) sites occur at least once per herpes simplex virus type 1 (HSV-1) genome. The parameters that control the ability of HSV-1 DNA polymerase (pol) to engage in AP translesion synthesis (TLS) were examined because AP lesions could influence the completion and fidelity of viral DNA synthesis. Pre-steady-state kinetic experiments demonstrated that wildtype (WT) and exonuclease-deficient (exo-) pol could incorporate opposite an AP lesion, but full TLS required absence of exo function. Virtually all of the WT pol was bound at the exo site to AP-containing primer-templates (P/Ts) at equilibrium, and the pre-steady-state rate of excision by WT pol was higher on AP-containing than on matched DNA. However, several factors influencing polymerization work synergistically with exo activity to prevent HSV-1 pol from engaging in TLS. Although the pre-steady-state catalytic rate constant for insertion of dATP opposite a T or AP site was similar, ground-state-binding affinity of dATP for insertion opposite an AP site was reduced 3-9-fold. Single-turnover running-start experiments demonstrated a reduced proportion of P/Ts extended to the AP site compared to the preceding site during processive synthesis by WT or exo- pol. Only the exo- pol engaged in TLS, though inefficiently and without burst kinetics, suggesting a much slower rate-limiting step for extension beyond the AP site.

Publication types

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

MeSH terms

  • Animals
  • Base Sequence
  • Chlorocebus aethiops
  • DNA Damage*
  • DNA Primers
  • DNA Repair*
  • DNA-Directed DNA Polymerase / metabolism*
  • Simplexvirus / enzymology*
  • Vero Cells


  • DNA Primers
  • DNA-Directed DNA Polymerase