DnaC is the AAA+ helicase loader of Escherichia coli. It binds DnaB, opens its hexameric ring and permits single-stranded DNA to enter during origin initiation and replication restart. DnaB and DNA stimulate DnaC ATP hydrolysis, coordinating remodeling and release of the loader as the helicase becomes active. DnaC is not the Bacillus DnaC helicase and is not a continuously required elongating-replisome motor.
Definition: Facilitating the opening or assembly of a replicative DNA helicase ring and its placement around single-stranded DNA, producing a loaded helicase competent for subsequent activation.
Justification: The demonstrated DnaC loading function is distinct from helicase unwinding, sequence-specific origin recognition and sliding-clamp loading. No appropriate bacterial helicase-loader GO molecular-function term was identified in the current QuickGO search.
Supporting Evidence:
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003688 DNA replication origin binding | IBA GO_REF:0000033 | UNDECIDED | Summary: The IBA carries a phylogenetic origin-binding judgment, and no PAINT loss was found. Reason: The IBA carries a phylogenetic origin-binding judgment, and no PAINT loss was found. DnaC is recruited at oriC, but direct structural evidence establishes ssDNA contact during helicase loading and does not by itself resolve origin-selective binding. Do not equate recruitment to oriC with DnaA-like origin recognition or reject the IBA solely from the familiar loader role. PAINT lineage-loss inspection found no applicable IRD/IKR; the IBA is evaluated as an ancestral-function judgment, not by counting listed donors. Propagation Review Root cause: UNRESOLVED Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN001574578 UNRESOLVED No lineage loss was reported. The inherited claim remains unresolved against target-specific ssDNA-loading evidence; no donor-count argument is made. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:15690043 Interaction network containing conserved and essential prote... | REMOVE | Summary: The reported interaction does not specify a useful molecular function. Reason: This row reports binding of dnaC to UniProtKB:P0ACB0 from PMID:15690043. Bare protein binding is uninformative under the project policy; removing the annotation does not deny the interaction. A partner list alone does not justify transferring the partner’s catalytic activity. Source availability and the distinction between focused interaction assays and large-scale screens are recorded in the reference notes. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:20129058 Primase directs the release of DnaC from DnaB. | REMOVE | Summary: The reported interaction does not specify a useful molecular function. Reason: This row reports binding of dnaC to UniProtKB:P0ACB0 from PMID:20129058. Bare protein binding is uninformative under the project policy; removing the annotation does not deny the interaction. A partner list alone does not justify transferring the partner’s catalytic activity. Source availability and the distinction between focused interaction assays and large-scale screens are recorded in the reference notes. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:23562643 The bacterial DnaC helicase loader is a DnaB ring breaker. | REMOVE | Summary: The reported interaction does not specify a useful molecular function. Reason: This row reports binding of dnaC to UniProtKB:P0ACB0 from PMID:23562643. Bare protein binding is uninformative under the project policy; removing the annotation does not deny the interaction. A partner list alone does not justify transferring the partner’s catalytic activity. Source availability and the distinction between focused interaction assays and large-scale screens are recorded in the reference notes. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:24561554 The binary protein-protein interaction landscape of Escheric... | REMOVE | Summary: The reported interaction does not specify a useful molecular function. Reason: This row reports binding of dnaC to UniProtKB:P0ACB0 from PMID:24561554. Bare protein binding is uninformative under the project policy; removing the annotation does not deny the interaction. A partner list alone does not justify transferring the partner’s catalytic activity. Source availability and the distinction between focused interaction assays and large-scale screens are recorded in the reference notes. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:8663105 The ordered assembly of the phiX174-type primosome. II. Pres... | REMOVE | Summary: The reported interaction does not specify a useful molecular function. Reason: This row reports binding of dnaC to UniProtKB:P0ACB0 from PMID:8663105. Bare protein binding is uninformative under the project policy; removing the annotation does not deny the interaction. A partner list alone does not justify transferring the partner’s catalytic activity. Source availability and the distinction between focused interaction assays and large-scale screens are recorded in the reference notes. Supporting Evidence: |
| GO:0005515 protein binding | IPI PMID:9562559 Three-dimensional reconstructions from cryoelectron microsco... | REMOVE | Summary: The reported interaction does not specify a useful molecular function. Reason: This row reports binding of dnaC to UniProtKB:P0ACB0 from PMID:9562559. Bare protein binding is uninformative under the project policy; removing the annotation does not deny the interaction. A partner list alone does not justify transferring the partner’s catalytic activity. Source availability and the distinction between focused interaction assays and large-scale screens are recorded in the reference notes. Supporting Evidence: |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: ATP binding is a mechanistic property of this nucleotide-regulated protein. Reason: ATP binding is a mechanistic property of this nucleotide-regulated protein. Binding is retained separately from the chemical or mechanical consequences of nucleotide turnover. Supporting Evidence: PMID:30797687 six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain |
| GO:0006260 DNA replication | NAS PMID:15749022 The disposition of nascent strands at stalled replication fo... | ACCEPT | Summary: dnaC directly participates in the chromosome-replication machinery through the activity described in its core function. Reason: dnaC directly performs DnaB ring opening and helicase loading within the replication machinery. This supports participation in chromosome replication; the pathway-level term remains informative alongside the specific molecular function and subcomplex assignments. Supporting Evidence: PMID:30797687 six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain |
| GO:0006260 DNA replication | NAS PMID:29202195 Mechanisms of bacterial DNA replication restart. | ACCEPT | Summary: dnaC directly participates in the chromosome-replication machinery through the activity described in its core function. Reason: dnaC directly performs DnaB ring opening and helicase loading within the replication machinery. This supports participation in chromosome replication; the pathway-level term remains informative alongside the specific molecular function and subcomplex assignments. Supporting Evidence: PMID:30797687 six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain |
| GO:0006269 DNA replication, synthesis of primer | NAS PMID:15749022 The disposition of nascent strands at stalled replication fo... | MARK AS OVER ANNOTATED | Summary: DnaC loads and initially restrains DnaB; primase engagement and primer formation trigger loader release. Reason: DnaC loads and initially restrains DnaB; primase engagement and primer formation trigger loader release. This does not establish a direct RNA-primer-synthesis function of DnaC. The demonstrated loading role is retained under replication initiation and fork processing. Supporting Evidence: |
| GO:0006269 DNA replication, synthesis of primer | NAS PMID:29202195 Mechanisms of bacterial DNA replication restart. | MARK AS OVER ANNOTATED | Summary: DnaC loads and initially restrains DnaB; primase engagement and primer formation trigger loader release. Reason: DnaC loads and initially restrains DnaB; primase engagement and primer formation trigger loader release. This does not establish a direct RNA-primer-synthesis function of DnaC. The demonstrated loading role is retained under replication initiation and fork processing. Supporting Evidence: |
| GO:0006270 DNA replication initiation | IBA GO_REF:0000033 | ACCEPT | Summary: Direct E. Reason: Direct E. coli structural and biochemical work shows DnaC opening the DnaB ring and loading the helicase onto DNA. This is an initiation function and a transient helicase-loader assembly. PAINT lineage-loss inspection found no applicable IRD/IKR; the IBA is evaluated as an ancestral-function judgment, not by counting listed donors. Supporting Evidence: PMID:30797687 six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain |
| GO:0006270 DNA replication initiation | IDA PMID:20129058 Primase directs the release of DnaC from DnaB. | ACCEPT | Summary: Direct E. Reason: Direct E. coli structural and biochemical work shows DnaC opening the DnaB ring and loading the helicase onto DNA. This is an initiation function and a transient helicase-loader assembly. Supporting Evidence: PMID:30797687 six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain |
| GO:0006270 DNA replication initiation | IDA PMID:30797687 Physical Basis for the Loading of a Bacterial Replicative He... | ACCEPT | Summary: Direct E. Reason: Direct E. coli structural and biochemical work shows DnaC opening the DnaB ring and loading the helicase onto DNA. This is an initiation function and a transient helicase-loader assembly. Supporting Evidence: PMID:30797687 six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain |
| GO:0006271 DNA strand elongation involved in DNA replication | IGI PMID:6277866 dnaC-dependent reconstitution of replication forks in Escher... | MODIFY | Summary: The cited lysate experiment explicitly finds ongoing replication independent of DnaC, while DnaC is required to replace defective DnaB at forks. Reason: The cited lysate experiment explicitly finds ongoing replication independent of DnaC, while DnaC is required to replace defective DnaB at forks. Replication-fork processing describes that recovery/reloading role more accurately than continuous strand elongation. Proposed replacements: replication fork processing Supporting Evidence: PMID:6277866 the replication machinery, once it is running along the chromosome, is independent of dnaC protein |
| GO:0016887 ATP hydrolysis activity | EXP PMID:30797687 Physical Basis for the Loading of a Bacterial Replicative He... | ACCEPT | Summary: DnaC hydrolyzes ATP in the DnaB–DNA loading complex. Reason: DnaC hydrolyzes ATP in the DnaB–DNA loading complex. The activity is partner/substrate dependent and coordinates remodeling after DNA engagement; initial ring opening is not equated with ATP hydrolysis. Supporting Evidence: PMID:30797687 Upon binding DNA, DnaC hydrolyzes ATP, allowing DnaB to isomerize into a topologically closed, pre-translocation state competent to bind primase. |
| GO:0031297 replication fork processing | NAS PMID:15749022 The disposition of nascent strands at stalled replication fo... | ACCEPT | Summary: The protein performs its loading, unwinding or priming function during origin-independent reassembly of stalled or collapsed replication forks. Reason: The protein performs its loading, unwinding or priming function during origin-independent reassembly of stalled or collapsed replication forks. Restart is supported separately from ordinary origin initiation. |
| GO:0031297 replication fork processing | NAS PMID:29202195 Mechanisms of bacterial DNA replication restart. | ACCEPT | Summary: The protein performs its loading, unwinding or priming function during origin-independent reassembly of stalled or collapsed replication forks. Reason: The protein performs its loading, unwinding or priming function during origin-independent reassembly of stalled or collapsed replication forks. Restart is supported separately from ordinary origin initiation. |
| GO:1990077 primosome complex | NAS PMID:15749022 The disposition of nascent strands at stalled replication fo... | ACCEPT | Summary: The protein participates in the primosome machinery. Reason: The protein participates in the primosome machinery. These assemblies are dynamic, and the loader need not remain bound during continued synthesis. |
| GO:1990077 primosome complex | NAS PMID:29202195 Mechanisms of bacterial DNA replication restart. | ACCEPT | Summary: The protein participates in the primosome machinery. Reason: The protein participates in the primosome machinery. These assemblies are dynamic, and the loader need not remain bound during continued synthesis. |
| GO:1990100 DnaB-DnaC complex | IPI PMID:30797687 Physical Basis for the Loading of a Bacterial Replicative He... | ACCEPT | Summary: Direct E. Reason: Direct E. coli structural and biochemical work shows DnaC opening the DnaB ring and loading the helicase onto DNA. This is an initiation function and a transient helicase-loader assembly. Supporting Evidence: PMID:30797687 six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain |
| GO:1990158 DnaB-DnaC-DnaT-PriA-PriB complex | NAS PMID:29202195 Mechanisms of bacterial DNA replication restart. | ACCEPT | Summary: The annotation describes a particular E. Reason: The annotation describes a particular E. coli replication-restart assembly involving helicase loading, not a universal bacterial primosome composition. Retain the curated complex assignment with its biochemical/review provenance; the exact higher-order assembly is transient. |
| GO:1990159 DnaB-DnaC-DnaT-PriA-PriC complex | NAS PMID:29202195 Mechanisms of bacterial DNA replication restart. | ACCEPT | Summary: The annotation describes a particular E. Reason: The annotation describes a particular E. coli replication-restart assembly involving helicase loading, not a universal bacterial primosome composition. Retain the curated complex assignment with its biochemical/review provenance; the exact higher-order assembly is transient. |
| GO:1990160 DnaB-DnaC-Rep-PriC complex | NAS PMID:15749022 The disposition of nascent strands at stalled replication fo... | ACCEPT | Summary: The annotation describes a particular E. Reason: The annotation describes a particular E. coli replication-restart assembly involving helicase loading, not a universal bacterial primosome composition. Retain the curated complex assignment with its biochemical/review provenance; the exact higher-order assembly is transient. |
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)