DNA polymerase III, beta sliding clamp, N-terminal (IPR022634)

Short name: DNA_polIII_beta_N

Overlapping homologous superfamilies


Domain relationships



DNA polymerase III is a complex, multichain holoenzyme responsible for most of the replicative synthesis in bacteria [PMID: 8548826]. It functions by adding nucleotide triphosphate (dNTP) residues to the 5'-end of a growing DNA chain, using a complementary DNA as template. The elongation factor beta-clamp, also called beta subunit, is part of the DNA polymerase III holoenzyme. However, beta-clamp is not attached to polymerase III permanently like the other subunits. It is loaded on the DNA, by clamp loader, a subunit of DNA Pol III [PMID: 27499105].

The beta clamp forms a ring shaped dimer that encircles dsDNA (sliding clamp) in bacteria. The bacterial beta clamp is a homodimer; each monomer consists of three globular domains to yield a six-domain ring [PMID: 18191219]. It is structurally similar to the trimeric ring formed by proliferating cell nuclear antigen (PCNA) (found in eukaryotes and archaea) and the processivity factor (found in bacteriophages T4 and RB69) [PMID: 1358275]. This structural correspondence further substantiates the mechanistic connection between eukaryotic and prokaryotic DNA replication that has been suggested on biochemical grounds.

This entry describes the N-terminal domain of the beta sliding clamp.

GO terms

Biological Process

GO:0006260 DNA replication

Molecular Function

GO:0008408 3'-5' exonuclease activity
GO:0003677 DNA binding
GO:0003887 DNA-directed DNA polymerase activity

Cellular Component

GO:0009360 DNA polymerase III complex

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.