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Function

DNA Polymerase IV is a polymerase present only in Escherichia coli (E. Coli), and is involved in non-targeted mutagenesis. PolIV is a Family Y polymerase, expressed by the dinB gene. Its activity is turned on when polymerases at the replication fork become stalled and exhibit SOS induction. It works to create a checkpoint and stop replication, to repair lesions in the DNA. Additionally, Pol IV acts as a trans-lesion synthesizer at a stalled replication fork.

Interactions

What it interacts with: This polymerase interacts with Pol III holoenzyme processivity, and occasionally has been proven to bypass N2-deoxyguanine adducts. It also repairs base-pair lesions, and connects directly to the DNA.

Where it interacts: It acts at stalled replication forks in the DNA of E. Coli; though it is poorly processive, it allows stationary-phase adaptive mutation, which provides the bacterium flexibility in dealing with environmental stress. Ser42 residue in the active site reacts with base pairs on the DNA directly, close to the minor groove.

Origin

The only organism in which DNA Polymerase IV originates is E. coli bacteria.