core primosome complex

GO:1990098 · Other · Nucleoprotein complex · Proposed

A protein-DNA complex containing at least one DNA helicase and one primase. Can also contain associated proteins. The helicase component continues to unwind the double-stranded DNA (dsDNA) and the primase component synthesizes a RNA primer during initiation or restart of replication. [GO:1990098]

Synonyms: core primosome

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

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
replicative DNA helicase	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Replicative helicase constituent that unwinds double-stranded DNA in the DNA-bound core primosome. `GO:1990098` GO:1990098 defines a core primosome as a protein-DNA complex containing at least one DNA helicase.
DNA primase	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Primase constituent that synthesizes RNA primer sequences after helicase-mediated DNA unwinding. `GO:1990098` GO:1990098 defines a core primosome as a protein-DNA complex containing at least one primase.
template DNA	Dna	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	DNA template scaffold for the helicase-primase core primosome. `GO:1990098` GO:1990098 defines the core primosome as a protein-DNA complex whose helicase continues to unwind double-stranded DNA.

Taxonomic distribution

NCBITaxon:562 Escherichia coli — COMMON: Kaguni 2011 reviewed E. coli chromosomal initiation from DnaB-DnaC loading through DnaG-dependent primer formation. [PMID:21856207]

Canonical examples

NCBITaxon:562 Escherichia coli — Kaguni 2011 describes DnaB helicase recruitment at oriC and subsequent primer formation by DnaG primase in the E. coli replication-initiation system. [PMID:21856207]

Functions

DNA replication, synthesis of primer GO:0006269 — The core primosome supports synthesis of a short RNA primer on an unwound DNA template.
- GO:1990098 GO:1990098 defines the primase component by RNA primer synthesis during initiation or restart of replication.
- GO:0006269 GO:0006269 defines DNA replication primer synthesis.
- PMID:21856207 Kaguni 2011 reviewed DnaG-dependent primer formation after DnaB-DnaC loading in the E. coli replication-initiation pathway.

Mechanism graphs

core primosome supports primer synthesis (FUNCTION)

A DNA-bound helicase-primase core primosome supports RNA primer synthesis on an unwound template during DNA replication.

Subject	Predicate	Object	Evidence
replicative DNA helicase	contributes to	core primosome complex	`GO:1990098` GO:1990098 defines the core primosome as containing at least one DNA helicase.
DNA primase	contributes to	core primosome complex	`GO:1990098` GO:1990098 defines the core primosome as containing at least one primase.
template DNA	scaffolds	core primosome complex	`GO:1990098` GO:1990098 defines the core primosome as a protein-DNA complex.
core primosome complex	supports	DNA replication, synthesis of primer	`GO:1990098` GO:1990098 defines the complex by helicase-mediated unwinding and primase RNA-primer synthesis. `GO:0006269` GO:0006269 defines DNA replication primer synthesis.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral helicase, primase and template-DNA groundings for the core primosome complex. GO:1990098 defines a protein-DNA complex containing a DNA helicase, primase and associated DNA template. Exact source-neutral InterPro, Pfam, NCBIfam, UniProt family or SO sequence-feature CURIEs for these components need narrower curation before the labels can be grounded.
INTERPRETATION (RESOLVED): Model the core primosome separately from the broader primosome, primase-lacking pre-primosomes and the protein-only DnaB-DnaG complex. GO:1990098 denotes a DNA-bound helicase-primase core, GO:1990077 denotes the broader primosome class, GO:1990099 denotes primase-lacking pre-primosomes, and species-specific helicase-primase protein subcomplexes such as GO:1990156 are narrower parts of particular core primosomes rather than generic GO:1990098 has_part structures.

Evidence

GO:1990098 Gene Ontology cellular-component term for the core primosome complex and its exact synonym.
GO:1990077 QuickGO reports GO:1990098 as an is-a descendant of GO:1990077 primosome complex.
GO:1990099 Gene Ontology cellular-component term for pre-primosome complexes, which lack a primase component.
GO:1990156 QuickGO models the DnaB-DnaG helicase-primase complex as part of GO:1990098.
GO:0006269 Gene Ontology biological-process term for DNA replication primer synthesis.
PMID:21856207 PubMed identifier for Kaguni 2011, the Current Opinion in Chemical Biology review cited by GO:1990098.
DOI:10.1016/j.cbpa.2011.07.016 DOI for Kaguni 2011, 'Replication initiation at the Escherichia coli chromosomal origin', as reported by PubMed.

Curation history

2026-10-01T09:17:58Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-01T09:19:20Z codex · EXPANDED_RECORD — Added GO synonymy, primosome parentage, DnaB-DnaG complex parthood, reviewed-label-only helicase/primase/template-DNA components, E. coli scope, DNA-replication-primer-synthesis function evidence, GO/PubMed/DOI evidence, a nonmechanistic primer-synthesis graph, and grounding/boundary discussions.
2026-10-01T09:31:13Z codex · FIX_DISCUSSION_ANCHORS — Replaced the bare components discussion attachment with concrete core-primosome component anchors.
2026-10-01T09:42:15Z codex · ADDRESS_REVIEW — #1864: Removed DnaB-DnaG complex from generic GO:1990098 has_part and the core-primosome graph, and narrowed the boundary discussion to leave species-specific helicase-primase protein subcomplexes out of the generic core record.

Source: data/structures/other/core_primosome_complex.yaml