Phosphorylation Alters the Properties of Pol ?: Implications for Translesion Synthesis.

ABSTRACT: There are significant ambiguities regarding how DNA polymerase ? is recruited to DNA lesion sites in stressed cells while avoiding normal replication forks in non-stressed cells. Even less is known about the mechanisms responsible for Pol ?-induced mutations in cancer genomes. We show that there are two safeguards to prevent Pol ? from adventitious participation in normal DNA replication. These include sequestration by a partner protein and low basal activity. Upon cellular UV irradiation, phosphorylation enables Pol ? to be released from sequestration by PDIP38 and activates its polymerase function through increased affinity toward monoubiquitinated proliferating cell nuclear antigen (Ub-PCNA). Moreover, the high-affinity binding of phosphorylated Pol ? to Ub-PCNA limits its subsequent displacement by Pol ?. Consequently, activated Pol ? replicates DNA beyond the lesion site and potentially introduces clusters of mutations due to its low fidelity. This mechanism could account for the prevalence of Pol ? signatures in cancer genome.

SUBMITTER: Peddu C 

PROVIDER: S-EPMC6137289 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature