The translesion polymerase Pol Y1 is a constitutive component of the B. subtilis replication machinery.

Unrepaired DNA damage encountered by the cellular replication machinery can stall DNA replication, ultimately leading to cell death. In the DNA damage tolerance pathway translesion synthesis (TLS), replication stalling is alleviated by the recruitment of specialized polymerases to synthesize short stretches of DNA near a lesion. Although TLS promotes cell survival, most TLS polymerases are low-fidelity and must be tightly regulated to avoid harmful mutagenesis.