| Primary Identifier | IPR001001 | Type | Family |
| Short Name | DNA_polIII_beta |
| description | DNA polymerase III is a complex, multichain holoenzyme responsible for most of the replicative synthesis in bacteria []. 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 β-clamp, also called beta subunit, is part of the DNA polymerase III holoenzyme. However, β-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 [].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 []. 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) []. This structural correspondence further substantiates the mechanistic connection between eukaryotic and prokaryotic DNA replication that has been suggested on biochemical grounds. |
