DNA polymerase III complex

GO:0009360 · Other · Multiprotein complex · Proposed

A DNA polymerase III holoenzyme complex organized into a Pol III core, a beta sliding-clamp processivity factor, and a clamp-loader complex that together support processive DNA replication. [GO:0009360]

Synonyms: DNA polymerase III holoenzyme complex

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Role
DNA polymerase III, core complex	Protein complex	part of	`GO:0044776`	Polymerase and proofreading-exonuclease subassembly of the DNA polymerase III holoenzyme. `GO:0044776` GO:0044776 defines the DNA polymerase III core complex as the alpha-, epsilon-, and theta-subunit assembly that carries out polymerase and 3'-5' exonuclease proofreading activities. `GO:0009360` GO:0009360 lists the Pol III core as one of the three functionally essential DNA polymerase III holoenzyme subassemblies.
DNA polymerase III, beta sliding clamp processivity factor complex	Protein complex	part of	`GO:0044775`	Sliding-clamp processivity factor that tethers the Pol III core to template DNA during high-speed replication. `GO:0044775` GO:0044775 defines the beta sliding-clamp processivity factor as the DNA polymerase III holoenzyme subcomplex that tethers the catalytic polymerase subunit to DNA. `GO:0009360` GO:0009360 lists the beta sliding-clamp processivity factor as one of the three functionally essential DNA polymerase III holoenzyme subassemblies.
DNA polymerase III, clamp loader complex	Protein complex	part of	`GO:0043846`	Clamp-loading subassembly that places the beta processivity factor on the primer-template and helps organize leading- and lagging-strand replication. `GO:0043846` GO:0043846 defines the DNA polymerase III clamp-loader complex as a heptamer that includes DnaX tau and gamma products plus the chi/psi subcomplex. `GO:0009360` GO:0009360 states that the clamp-loading complex assembles the beta processivity factor onto the primer template.

Canonical examples

NCBITaxon:562 Escherichia coli — Source species for a DNA polymerase III holoenzyme reconstitution from purified subunits. [PMID:3283127]

Functions

DNA-directed DNA polymerase activity GO:0003887 — The DNA polymerase III holoenzyme carries out template-directed DNA strand extension while its clamp-loader and beta-clamp subassemblies support processivity at the replication fork.
- GO:0003887 GO:0003887 defines DNA-directed DNA polymerase activity as DNA-template-directed extension of the 3'-end of a DNA strand.
- GO:0009360 GO:0009360 defines the DNA polymerase III holoenzyme as a Pol III core, beta sliding-clamp, and clamp-loader assembly that functions at the replication fork.

Mechanism graphs

DNA polymerase III carries out processive DNA synthesis (FUNCTION)

The DNA polymerase III holoenzyme combines the Pol III core, beta sliding clamp, and clamp-loader subassemblies to support DNA-template-directed primer extension.

Subject	Predicate	Object	Evidence
DNA polymerase III complex	enables	DNA-directed DNA polymerase activity	`GO:0009360` GO:0009360 defines the DNA polymerase III holoenzyme around the Pol III core that carries out DNA polymerase activity. `GO:0003887` GO:0003887 defines DNA-directed DNA polymerase activity.
DNA polymerase III, core complex	contributes to	DNA-directed DNA polymerase activity	`GO:0044776` GO:0044776 defines the core as the DNA polymerase III subcomplex that carries out polymerase and 3'-5' exonuclease proofreading activities.
DNA polymerase III, beta sliding clamp processivity factor complex	tethers	DNA polymerase III, core complex	`GO:0044775` GO:0044775 defines the beta sliding-clamp complex by its responsibility for tethering the catalytic subunit of DNA polymerase to DNA during high-speed replication.
DNA polymerase III, clamp loader complex	loads	DNA polymerase III, beta sliding clamp processivity factor complex	`GO:0009360` GO:0009360 states that the DNA polymerase III clamp-loading complex assembles the beta processivity factor onto the primer template. `GO:0003689` GO:0003689 defines DNA clamp-loader activity.
DNA-directed DNA polymerase activity	extends	primer-template DNA	`GO:0003887` GO:0003887 defines DNA-directed DNA polymerase activity as template-directed extension of the 3'-end of a DNA strand.
DNA polymerase III complex	supports	DNA replication	`GO:0009360` GO:0009360 defines the DNA polymerase III holoenzyme as a replication-fork complex. `GO:0006260` GO:0006260 is the biological-process term for DNA replication.

Evidence

GO:0009360 Gene Ontology cellular-component term for the DNA polymerase III complex.
GO:0042575 Gene Ontology cellular-component term for DNA polymerase complexes, the broader class that includes the DNA polymerase III complex.
GO:0044776 Gene Ontology cellular-component term for the DNA polymerase III core complex.
GO:0044775 Gene Ontology cellular-component term for the DNA polymerase III beta sliding-clamp processivity factor complex.
GO:0043846 Gene Ontology cellular-component term for the DNA polymerase III clamp-loader complex.
GO:0003887 Gene Ontology molecular-function term for DNA-directed DNA polymerase activity.
GO:0006260 Gene Ontology biological-process term for DNA replication.
GO:0003689 Gene Ontology molecular-function term for DNA clamp-loader activity.
UniProtKB:P06710 UniProtKB reviewed Escherichia coli K-12 entry for DnaX, the DNA polymerase III tau/gamma subunit referenced by the GO:0009360 definition.
PMID:11525729 PubMed identifier for Jeruzalmi, O'Donnell, and Kuriyan 2001, Crystal structure of the processivity clamp loader gamma complex of E. coli DNA polymerase III.
DOI:10.1016/s0092-8674(01)00463-9 DOI for Jeruzalmi, O'Donnell, and Kuriyan 2001 as reported by PubMed.
PMID:12940977 PubMed identifier for McHenry 2003, Chromosomal replicases as asymmetric dimers: studies of subunit arrangement and functional consequences.
DOI:10.1046/j.1365-2958.2003.03645.x DOI for McHenry 2003 as reported by PubMed.
PMID:3283127 PubMed identifier for Maki and Kornberg 1988, DNA polymerase III holoenzyme of Escherichia coli. III. Distinctive processive polymerases reconstituted from purified subunits.

Curation history

2026-09-24T11:03:50Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-24T11:05:01Z codex · EXPANDED_RECORD — Added DNA polymerase complex parentage, the GO-backed holoenzyme synonym, GO-grounded Pol III core, beta-clamp, and clamp-loader subcomplex components, an Escherichia coli K-12 canonical example, DNA-directed DNA polymerase function evidence, and a compact processive DNA synthesis graph.
2026-09-24T11:16:13Z codex · ADDRESS_REVIEW — #1481: replaced the UniProtKB-backed E. coli K-12 canonical example with an E. coli example directly supported by PMID:3283127, a whole-holoenzyme reconstitution study.

Source: data/structures/other/dna_polymerase_iii_complex.yaml