DNA Polymerase V (Pol V) is a
polymerase enzyme involved in
DNA repair mechanisms in the bacteria
Escherichia coli. It is composed of a UmuD’
homodimer and a UmuC
monomer, forming the UmuD’2C protein complex. It is part of the Y-family of DNA Polymerases, which are capable of performing DNA
translesion synthesis (TLS). Translesion polymerases bypass DNA damage lesions during
DNA replication, if a lesion is not repaired or bypassed the
replication fork can stall and lead to cell death. However, Y polymerases have low sequence fidelity during replication (prone to add wrong nucleotides). When the UmuC and UmuD’ proteins were initially discovered in
E. coli, they were thought to be agents that inhibit faithful DNA replication and caused DNA synthesis to have high mutation rates after exposure to
UV-light. The polymerase function of Pol V was not discovered until the late 1990s when UmuC was successfully extracted, consequent experiments unequivocally proved UmuD’2C is a polymerase. This finding lead to the detection of many Pol V
orthologs and the discovery of the Y-family of polymerases.
