In vitro lesion bypass by human PrimPol.

Many human DNA polymerases bypass DNA damage during translesion synthesis (TLS). Human primase and polymerase, PrimPol, assists fork progression by repriming DNA synthesis downstream of the lesion using its DNA primase activity. We tested the properties of PrimPol as a TLS polymerase in the presence of different metal ions in vitro. We demonstrate that in the presence of Mg ions PrimPol carries out efficient and relatively accurate synthesis past 8-oxoguanine and 5-formyluracil. It also bypasses an abasic site and O-methylguanine, but is blocked by thymine glycol and 1,N-ethenoadenine. Substitution of Mg with Mn stimulates the TLS activity of PrimPol and allows for efficient, but error-prone, synthesis on DNA templates containing all tested DNA lesions, including thymine glycol and 1,N-ethenoadenine. The TLS activity of PrimPol has possible relevant functions in vivo; e.g., the combined primase and DNA polymerase activities of PrimPol might facilitate replication of DNA with clustered damage.