DnaB-DnaC complex
A protein complex containing homohexameric DNA helicase DnaB, and the DNA helicase loader DnaC. The helicase loader DnaC delivers DnaB to the chromosomal origin (oriC). [GO:1990100]
Synonyms: DnaB6-DnaC3 complex; DnaB6-DnaC6 complex; helicase-loading complex
Components
| Component | Type | Part of / acts on | Grounding | Genes | Stoichiometry | Essential | Role |
|---|---|---|---|---|---|---|---|
| DnaB helicase | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | dnaB | 6 copies per DnaB homohexamer | UNKNOWN | Homohexameric DNA helicase constituent of the DnaB-DnaC helicase-loading complex.
|
| DnaC helicase loader | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | dnaC | UNKNOWN | Helicase-loader constituent that delivers DnaB to the chromosomal origin.
|
Taxonomic distribution
NCBITaxon:562Escherichia coli — COMMON: Makowska-Grzyska and Kaguni 2010 studied DnaB-DnaC helicase loading at the E. coli chromosomal origin. [PMID:20129058]
Canonical examples
NCBITaxon:562Escherichia coli — Makowska-Grzyska and Kaguni 2010 used the E. coli DnaB-DnaC system to quantify DnaC occupancy on the DnaB hexamer and to dissect DnaC release during replication initiation. [PMID:20129058]
Functions
- DNA replication initiation
GO:0006270— The DnaB-DnaC complex participates in bacterial DNA replication initiation by delivering DnaB helicase to the chromosomal origin.GO:1990100GO:1990100 defines the DnaB-DnaC complex by DnaC-mediated DnaB delivery to the chromosomal origin.GO:0006270GO:0006270 is the Gene Ontology biological-process term for DNA replication initiation.PMID:20129058Makowska-Grzyska and Kaguni 2010 dissected DnaC release from a DnaB-DnaC prepriming intermediate at oriC.
Mechanism graphs
DnaC delivers DnaB to oriC (FUNCTION)
The DnaB-DnaC complex combines a DnaB helicase hexamer with DnaC helicase loader to deliver DnaB to oriC during DNA replication initiation.
| Subject | Predicate | Object | Evidence |
|---|---|---|---|
| DnaB helicase | contributes to | DnaB-DnaC complex |
|
| DnaC helicase loader | contributes to | DnaB-DnaC complex |
|
| DnaB-DnaC complex | delivers helicase to | chromosomal origin oriC |
|
| DnaB-DnaC complex | supports | DNA replication initiation |
|
Discussions
- CURATION_TODO (OPEN): Resolve exact source-neutral DnaB and DnaC family groundings for the DnaB-DnaC complex. GO:1990100 defines DnaB and DnaC as constituents of this helicase-loading complex. Exact source-neutral InterPro, Pfam, NCBIfam or UniProt family boundaries for these component classes need narrower curation before the labels can be grounded.
- INTERPRETATION (RESOLVED): Leave DnaC stoichiometry unresolved rather than choosing a DnaB6-DnaC3 or DnaB6-DnaC6 narrow subcomplex. GO:1990100 uses DnaB6-DnaC3 and DnaB6-DnaC6 as narrow synonyms for the broader DnaB-DnaC complex. The broader record can safely assert hexameric DnaB from the GO definition without committing the DnaC component row to one narrower loading-state stoichiometry.
Evidence
GO:1990100Gene Ontology cellular-component term for the DnaB-DnaC complex and its narrow and broad synonymy.GO:0032991OLS reports GO:0032991 protein-containing complex as the direct GO:1990100 is-a parent.GO:0006270Gene Ontology biological-process term for DNA replication initiation.PMID:20129058PubMed identifier for Makowska-Grzyska and Kaguni 2010, the Molecular Cell paper cited by GO:1990100.DOI:10.1016/j.molcel.2009.12.031DOI for Makowska-Grzyska and Kaguni 2010, 'Primase directs the release of DnaC from DnaB', as reported by PubMed.
Curation history
2026-10-01T02:37:06Zcodex · CREATED_RECORD — Scaffolded by scripts/new_record.py2026-10-01T02:39:03Zcodex · EXPANDED_RECORD — Added GO synonymy, protein-containing-complex parentage, DnaB and DnaC reviewed-label-only components, E. coli scope, DNA-replication-initiation function evidence, GO/PubMed/DOI evidence, a nonmechanistic helicase-loading graph, and grounding/stoichiometry discussions.2026-10-01T03:01:11Zcodex · FIX_REVIEW_ISSUE — #1851: replaced the GO-backed E. coli taxonomic row with primary DnaB-DnaC evidence.