pre-primosome complex

GO:1990099 · Other · Nucleoprotein complex · Proposed

Any of the protein-DNA complexes that contain a DNA helicase and associated protein(s) at the origin of replication, and build up to assembling the core primosome. The associated protein(s) chaperone the helicase to the DNA, and assembly of the pre-primosome is essential for the initiation or restart of replication. Pre-primosome complexes lack a primase component. [GO:1990099]

Synonyms: pre-priming complex; pre-primosome; preprimosome; preprimosome complex; prereplication complex; pre-replication complex

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

Components

Component	Type	Part of / acts on	Grounding	Essential	Role
DNA helicase	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Replicative helicase constituent chaperoned to origin or restart DNA before primase-containing core primosome assembly. `GO:1990099` GO:1990099 defines pre-primosome complexes as protein-DNA complexes that contain a DNA helicase.
helicase-chaperoning replication protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	Associated replication protein that chaperones the DNA helicase to replication-origin or restart DNA before primase recruitment. `GO:1990099` GO:1990099 defines pre-primosome associated proteins as chaperoning the helicase to DNA.
replication initiation or restart DNA	Dna	part of	Reviewed label only (reviewed name; no accession asserted)	UNKNOWN	DNA scaffold that receives the chaperoned helicase during pre-primosome assembly. `GO:1990099` GO:1990099 defines pre-primosomes as protein-DNA complexes that contain a helicase at the replication origin and build toward a core primosome.

Taxonomic distribution

NCBITaxon:562 Escherichia coli — COMMON: Ng and Marians 1996 isolated PhiX174-type E. coli preprimosomal and primosomal protein-DNA complexes assembled on single-stranded primosome assembly site DNA. [PMID:8663105]

Canonical examples

NCBITaxon:562 Escherichia coli — Ng and Marians 1996 isolated PhiX174-type E. coli preprimosomal and primosomal protein-DNA complexes during ordered primosome assembly on single-stranded DNA. [PMID:8663105]

Functions

DNA replication initiation GO:0006270 — Pre-primosome complexes position a DNA helicase during replication initiation before primase-containing core primosome assembly.
- GO:1990099 GO:1990099 defines pre-primosome assembly as essential for initiation or restart of replication.
replication fork processing GO:0031297 — Some pre-primosome complexes assemble during restart after a stalled replication fork has been repaired.
- GO:1990158 GO:1990158 is a pre-primosome child term defined by replication restart after stalled-fork repair.
- GO:1990160 GO:1990160 is a Rep/PriC pre-primosome child term defined by replication restart after stalled-fork repair.
- GO:0031297 GO:0031297 defines replication fork processing as restoration and restart of a stalled DNA replication fork.

Mechanism graphs

pre-primosome positions helicase before primase recruitment (FUNCTION)

An associated replication protein chaperones a DNA helicase to an origin or restart DNA scaffold to form a primase-lacking pre-primosome used during replication initiation or restart.

Subject	Predicate	Object	Evidence
DNA helicase	contributes to	pre-primosome complex	`GO:1990099` GO:1990099 defines pre-primosomes as containing a DNA helicase.
helicase-chaperoning replication protein	contributes to	pre-primosome complex	`GO:1990099` GO:1990099 defines pre-primosomes as containing associated proteins that chaperone the helicase to DNA.
replication initiation or restart DNA	scaffolds	pre-primosome complex	`GO:1990099` GO:1990099 defines the pre-primosome as a protein-DNA complex.
pre-primosome complex	supports	DNA replication initiation	`GO:1990099` GO:1990099 defines pre-primosome assembly as essential for replication initiation or restart.
pre-primosome complex	supports	replication fork processing	`GO:1990158` GO:1990158 is a GO:1990099 child involved in replication restart after stalled-fork repair. `GO:1990159` GO:1990159 is a GO:1990099 child involved in replication restart after stalled-fork repair. `GO:0031297` GO:0031297 defines replication fork processing as restoration and restart of a stalled DNA replication fork.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral DNA-helicase, helicase-chaperone and replication-site DNA groundings for the pre-primosome complex. GO:1990099 defines the generic pre-primosome as a protein-DNA complex containing a DNA helicase, associated proteins that chaperone the helicase to DNA, and replication-origin or restart DNA. 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 generic pre-primosome complex separately from concrete DnaB-DnaC pre-primosomes and primase-containing core primosomes. GO:1990099 denotes a primase-lacking pre-primosome class. GO models GO:1990157, GO:1990158, GO:1990159 and GO:1990160 as narrower is-a children rather than as parts of every pre-primosome, and GO:1990098 models helicase-primase core primosomes separately.

Evidence

GO:1990099 Gene Ontology cellular-component term for the pre-primosome complex and its exact pre-primosome, preprimosome and pre-priming-complex synonymy.
GO:1990077 QuickGO reports GO:1990099 as an is-a child of GO:1990077 primosome complex.
GO:1990157 QuickGO reports GO:1990157 DnaA-DnaB-DnaC complex as a pre-primosome child of GO:1990099.
GO:1990158 QuickGO reports GO:1990158 DnaB-DnaC-DnaT-PriA-PriB complex as a pre-primosome child of GO:1990099.
GO:1990159 QuickGO reports GO:1990159 DnaB-DnaC-DnaT-PriA-PriC complex as a pre-primosome child of GO:1990099.
GO:1990160 QuickGO reports GO:1990160 DnaB-DnaC-Rep-PriC complex as a pre-primosome child of GO:1990099.
GO:0006270 Gene Ontology biological-process term for DNA replication initiation.
GO:0031297 Gene Ontology biological-process term for replication fork processing.
PMID:18179598 PubMed identifier for Chodavarapu et al. 2008, one of the papers cited by GO:1990099.
DOI:10.1111/j.1365-2958.2007.06094.x DOI for Chodavarapu et al. 2008, 'Escherichia coli DnaA interacts with HU in initiation at the E. coli replication origin', as reported by PubMed.
PMID:20129058 PubMed identifier for Makowska-Grzyska and Kaguni 2010, the Molecular Cell DnaB-DnaC paper cited by GO:1990099.
DOI:10.1016/j.molcel.2009.12.031 DOI for Makowska-Grzyska and Kaguni 2010, 'Primase directs the release of DnaC from DnaB', as reported by PubMed.
PMID:8663105 PubMed identifier for Ng and Marians 1996 part II, the Journal of Biological Chemistry paper cited by GO:1990099.
DOI:10.1074/jbc.271.26.15649 DOI for Ng and Marians 1996, 'The ordered assembly of the phiX174-type primosome. II. Preservation of primosome composition from assembly through replication', as reported by PubMed.

Curation history

2026-10-01T10:08:54Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-01T10:10:15Z codex · EXPANDED_RECORD — Added GO synonymy, primosome parentage, reviewed-label-only helicase, associated-protein and replication-site-DNA components, E. coli pre-primosome evidence, initiation and replication-restart function evidence, a nonmechanistic pre-primosome graph, and grounding/boundary discussions.
2026-10-01T10:23:19Z codex · FIX_REVIEW_ISSUE — #1866: Replaced the GO-backed E. coli taxonomic-distribution row with direct Ng and Marians PhiX174-type preprimosome evidence.

Source: data/structures/other/pre_primosome_complex.yaml