Pol ? ribonucleotide insertion opposite 8-oxodG facilitates the ligation of premutagenic DNA repair intermediate.

ABSTRACT: DNA polymerase (pol) ? primarily inserts ribonucleotides into a single-nucleotide gapped DNA intermediate, and the ligation step plays a critical role in the joining of noncomplementary DNA ends during nonhomologous end joining (NHEJ) for the repair of double-strand breaks (DSBs) caused by reactive oxygen species. Here, we report that the pol ? insertion products of ribonucleotides (rATP or rCTP), instead of deoxyribonucleotides, opposite 8-oxo-2'-deoxyguanosine (8-oxodG) are efficiently ligated and the presence of Mn²⁺ stimulates this coupled reaction in vitro. Moreover, our results point to a role of pol ? in mediating ligation during the mutagenic bypass of 8-oxodG, while 3'-preinserted noncanonical base pairs (3'-rA or 3'-rC) on NHEJ repair intermediates compromise the end joining by DNA ligase I or the DNA ligase IV/XRCC4 complex.

SUBMITTER: Caglayan M 

PROVIDER: S-EPMC6976671 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature