DNA polymerase type-II B subfamily catalytic domain. Bacteria contain five DNA polymerases (I, II, III, IV and V). DNA polymerase II (Pol II) is a prototype for the B-family of polymerases. The role of Pol II in a variety of cellular activities, such as repair of DNA damaged by UV irradiation or oxidation has been proved by genetic studies. DNA polymerase III is the main enzyme responsible for replication of the bacterial chromosome; however, In vivo studies have also shown that Pol II is able to participate in chromosomal DNA replication with larger role in lagging-strand replication.