Residues in the fingers domain of the translesion DNA polymerase DinB enable its unique participation in error-prone double-strand break repair.

The evolutionarily conserved translesion DNA polymerase IV (DinB) is one of three enzymes that can bypass potentially deadly DNA lesions on the template strand during DNA replication. Remarkably, however, DinB is the only known translesion DNA polymerase active in RecA-mediated strand exchange during error-prone double-strand break repair. In this process, a single-stranded DNA (ssDNA)-RecA nucleoprotein filament invades homologous dsDNA, pairing the ssDNA with the complementary strand in the dsDNA.