Homologous Superfamily

DNA polymerase III-theta superfamily (IPR036745)

Short name: PolIII_theta_sf

Overlapping entries


This entry represents the theta subunit of DNA polymerase III from bacteria, whose core structure consists of an irregular array of three helices [PMID: 10794414].

DNA polymerase III (Pol III) is the primary enzyme responsible for replication of Escherichia coli chromosomal DNA. The holoenzyme consists of 17 proteins and contains two core polymerases. The Pol III catalytic core has three tightly associated subunits: alpha, epsilon and theta. The alpha subunit is responsible for the DNA polymerase activity, while the epsilon subunit is the 3'-5' proofreading exonuclease. The epsilon subunit binds to both the alpha and theta subunits in the linear order alpha-epsilon-theta. The theta subunit is the smallest, and may act to enhance the proofreading activity of epsilon, especially under extreme conditions [PMID: 16753031].

This entry also includes a homologue of polymerase III theta called HOT (homologue of theta) from Bacteriophage P1. HOT contains three alpha-helices, as reported for theta, but the folding topology of the two is different, which could account for the suggested greater heat stability of HOT as compared to theta [PMID: 15576035].

GO terms

Biological Process

GO:0006260 DNA replication

Molecular Function

GO:0003677 DNA binding
GO:0003887 DNA-directed DNA polymerase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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