DNA polymerase I

DNA polymerase I
Functional domains in the Klenow Fragment (left) and DNA Polymerase I (right).
Identifiers
Organism	Escherichia coli (str. K-12 substr. MG1655)
Symbol	polA
Entrez	948356
PDB	1DPI
RefSeq (Prot)	NP_418300.1
UniProt	P00582
Other data
EC number	2.7.7.7
Chromosome	genome: 4.04 - 4.05 Mb
Search for Structures Swiss-model Domains InterPro

DNA polymerase I (or Pol I) is an enzyme that participates in the process of prokaryotic DNA replication. Discovered by Arthur Kornberg in 1956,^[1] it was the first known DNA polymerase (and the first known of any kind of polymerase). It was initially characterized in E. coli and is ubiquitous in prokaryotes. In E. coli and many other bacteria, the gene that encodes Pol I is known as polA. The E. coli Pol I enzyme is composed of 928 amino acids, and is an example of a processive enzyme — it can sequentially catalyze multiple polymerisation steps without releasing the single-stranded template.^[2] The physiological function of Pol I is mainly to support repair of damaged DNA, but it also contributes to connecting Okazaki fragments by deleting RNA primers and replacing the ribonucleotides with DNA.