Replication and repair of a reduced 2?-deoxyguanosine-abasic site interstrand cross-link in human cells.

ABSTRACT: Apurinic/apyrimidinic (AP) sites, or abasic sites, which are a common type of endogenous DNA damage, can forge interstrand DNA-DNA cross-links via reaction with the exocyclic amino group on a nearby 2?-deoxyguanosine or 2?-deoxyadenosine in the opposite strand. Here, we utilized a shuttle vector method to examine the efficiency and fidelity with which a reduced dG-AP cross-link-containing plasmid was replicated in cultured human cells. Our results showed that the cross-link constituted strong impediments to DNA replication in HEK293T cells, with the bypass efficiencies for the dG- and AP-containing strands being 40% and 20%, respectively. While depletion of polymerase (Pol) ? did not perturb the bypass efficiency of the lesion, the bypass efficiency was markedly reduced (to 1-10%) in the isogenic cells deficient in Pol ?, Pol ? or Pol ?, suggesting the mutual involvement of multiple translesion synthesis polymerases in bypassing the lesion. Additionally, replication of the cross-linked AP residue in HEK293T cells was moderately error-prone, inducing a total of ?26% single-nucleobase substitutions at the lesion site, whereas replication past the cross-linked dG component occurred at a mutation frequency of ?8%. Together, our results provided important insights into the effects of an AP-derived interstrand cross-link on the efficiency and accuracy of DNA replication in human cells.

SUBMITTER: Price NE 

PROVIDER: S-EPMC5499640 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature