E. coli DNA Polymerase II

DNA Polymerase II - A combination of circumstances lead to the discovery of polymerase II. First, polymerase I did not have properties expected of a polymerase that replicated the E. coli genome. It was too slow and there were too many copies of it compared to the number of replication forks. In 1969, the isolation of an E. coli mutant deficient in DNA polymerase I activity lead to the detection of DNA polymerases II and III. It was not possible to detect these enzymes in normal cells due to the relatively large amounts of polymerase I. Polymerase II appears to participate in DNA repair synthesis and does not have a significant role in DNA replication.