A DNA polymerase involved in DNA replication in prokaryotes, is encoded by polB gene, and composed of 783 amino acids
DNA polymerases are enzymes that assist in the replication of DNA. In prokaryotes, examples of these enzymes are DNA polymerases I, II, and III. The first known DNA polymerase is DNA polymerase I and was observed in E. coli. It is encoded by the gene polA. DNA polymerase II or Pol II is an 89.9 kDa protein, comprised of 786 amino acids, and encoded by polB gene. It was first isolated by Thomas Kornberg in 19701 whereas the first crystallization was done by Anderson and others in 19942. DNA polymerase II is a member of the B family of DNA polymerases. It is involved both in replicative and reparative processes, particularly in a 5’3′ DNA-dependent DNA polymerase activity and in 3’5′ exonuclease proofreading activity.
- Pol II
1 Kornberg, T. and Gefter, M. L. (1970). “DNA synthesis in cell-free extracts of a DNA polymerase-defective mutant”. Biochem. Biophys. Res. Commun. 40 (6): 1348–55.
2 Anderson, W. F., Prince, D. B., Yu, H., McEntee, K., and Goodman, M. F. (Apr 1994). “Crystallization of DNA polymerase II from Escherichia coli”. Journal of Molecular Biology 238 (1): 120–2.