Roles of DNA polymerases V and II in SOS-induced error-prone and error-free repair in Escherichia coli

DNA polymerase V, composed of a heterotrimer of the DNA damage-inducible Um uC and UmuD(2)' proteins, working in conjunction with RecA, single-stranded DNA (ssDNA)-binding protein (SSB), beta sliding clamp, and gamma clamp loa ding complex, are responsible for most SOS lesion-targeted mutations in Esc herichia coli, by catalyzing translesion synthesis (TLS). DNA polymerase II , the product of the damage-inducible polB (dinA) gene plays a pivotal role in replication-restart, a process that bypasses DNA damage in an error-fre e manner. Replication-restart takes place almost immediately after the DNA is damaged (approximate to min post-UV irradiation), whereas TLS occurs aft er pol V is induced approximate to 50 min later. We discuss recent data for pol V-catalyzed TLS and pol II-catalyzed replication-restart. Specific rol es during TLS for pol V and each of its accessory factors have been recentl y determined. Although the precise molecular mechanism of pol II-dependent replication-restart remains to be elucidated, it has recently been shown to operate in conjunction with RecFOR and PriA proteins.