synthetic metagenome Metagenome

Primase-polymerases (PP) play diverse functions from DNA replication to DNA repair in all three domains of life. A group of PPs are genetically associated with prokaryotic Argonaute proteins (pAgos) and their functions remain unknown. Here we reveal that the pAgo-associated PP (AgaPP) is derived from mobile genetic elements (MGEs). AgaPP has polymerase and primase activities and physically interacts with a helicase encoded by its downstream gene, suggesting that they constitute a functional replication module. Further, AgaPP performs translesion DNA synthesis, terminal transfer and microhomology-mediated end joining (MMEJ), showing striking similarity to human DNA repair polymerase theta. AgaPP can promote cell survival post DNA damage and repair the Cas9-induced double-stranded DNA breaks in E. coli. In addition, the MMEJ activity of AgaPP can be repurposed to assist DNA assembly in vitro. Together, the findings suggest that AgaPP may function in DNA both replication and repair.