P0ACB0 · DNAB_ECOLI
- ProteinReplicative DNA helicase DnaB
- GenednaB
- StatusUniProtKB reviewed (Swiss-Prot)
- Organism
- Amino acids471 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
The main replicative DNA helicase, it participates in initiation and elongation during chromosome replication. Travels ahead of the DNA replisome, separating dsDNA into templates for DNA synthesis. A processive ATP-dependent 5'-3' DNA helicase that acts on preformed replication forks (have single-stranded (ss)DNA tails) (PubMed:3007474).
ATP is the best nucleotide for helicase activity; GTP, CTP, dCTP and dATP are poor substitutes (PubMed:3007474).
Participates with DNA primase DnaG in primer RNA (pRNA) synthesis during initiation of DNA replication (PubMed:7532169).
Has DNA-dependent ATPase activity (PubMed:7532169).
Is loaded onto ssDNA via the action of DnaC; ssDNA binds to the central pore in the DnaB6:DnaC6 complex, making contacts with both subunits (PubMed:30797687).
ATP is the best nucleotide for helicase activity; GTP, CTP, dCTP and dATP are poor substitutes (PubMed:3007474).
Participates with DNA primase DnaG in primer RNA (pRNA) synthesis during initiation of DNA replication (PubMed:7532169).
Has DNA-dependent ATPase activity (PubMed:7532169).
Is loaded onto ssDNA via the action of DnaC; ssDNA binds to the central pore in the DnaB6:DnaC6 complex, making contacts with both subunits (PubMed:30797687).
Deletion or mutations in this gene were selected in directed evolution experiments for resistance to intense ionizing radiation (3000 Gy) (PubMed:24596148).
Catalytic activity
- Couples ATP hydrolysis with the unwinding of duplex DNA at the replication fork by translocating in the 5'-3' direction. This creates two antiparallel DNA single strands (ssDNA). The leading ssDNA polymer is the template for DNA polymerase III holoenzyme which synthesizes a continuous strand.
- ATP + H2O = ADP + H+ + phosphate
Cofactor
Note: Hexameric enzyme depends on Mg2+; in its absence, DnaB is trimeric (PubMed:7989299).
Activity regulation
5'-3' DNA helicase activity is stimulated 2-fold by single-stranded binding protein (SSB) and 6-fold by SSB and DnaG primase (PubMed:3007474).
Features
Showing features for binding site.
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | cytosol | |
Cellular Component | DNA helicase complex | |
Cellular Component | DnaB-DnaC complex | |
Cellular Component | DnaB-DnaC-DnaT-PriA-PriB complex | |
Cellular Component | DnaB-DnaC-DnaT-PriA-PriC complex | |
Cellular Component | DnaB-DnaC-Rep-PriC complex | |
Cellular Component | DnaB-DnaG complex | |
Cellular Component | primosome complex | |
Cellular Component | replisome | |
Molecular Function | 5'-3' DNA helicase activity | |
Molecular Function | ATP binding | |
Molecular Function | ATP hydrolysis activity | |
Molecular Function | DNA binding | |
Molecular Function | DNA helicase activity | |
Molecular Function | helicase activity | |
Molecular Function | identical protein binding | |
Molecular Function | isomerase activity | |
Biological Process | DNA duplex unwinding | |
Biological Process | DNA replication | |
Biological Process | DNA replication initiation | |
Biological Process | DNA replication, synthesis of primer | |
Biological Process | DNA unwinding involved in DNA replication | |
Biological Process | replication fork processing | |
Biological Process | response to ionizing radiation |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameReplicative DNA helicase DnaB
- EC number
- Alternative names
Gene names
Organism names
- Organism
- Strains
- Taxonomic lineageBacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia
Accessions
- Primary accessionP0ACB0
- Secondary accessions
Proteomes
Subcellular Location
Keywords
- Cellular component
Phenotypes & Variants
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 81 | About 100-fold increased survival following 3000 Gy ionizing radiation. | ||||
Sequence: P → H | ||||||
Mutagenesis | 130 | In dnaB8, dnaB43, dnaB454; temperature sensitive, no DNA replication at 42 degrees Celsius in vivo, in vitro decreased helicase activity at 30, at 42 degrees Celius almost no helicase, no synthesis of primer RNA (pRNA), low ATPase activity, still binds ssDNA. | ||||
Sequence: A → V | ||||||
Mutagenesis | 242 | In dnaB70; temperature sensitive, no DNA replication at 42 degrees Celsius in vivo, in vitro 25% helicase activity at 30, further decreased helicase at 42 degrees Celius, low ATPase activity at 30 and 42 degrees Celsius, reduced synthesis of pRNA at 30, no pRNA synthesis at 42 degrees Celsius. | ||||
Sequence: M → I | ||||||
Mutagenesis | 299 | In dnaB252; temperature sensitive, no DNA replication at 42 degrees Celsius in vivo, in vitro no change in pRNA synthesis, 5'-3' helicase activity or ATPase at either temperature. | ||||
Sequence: G → D |
PTM/Processing
Features
Showing features for initiator methionine, chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Initiator methionine | 1 | Removed | ||||
Sequence: M | ||||||
Chain | PRO_0000102019 | 2-471 | Replicative DNA helicase DnaB | |||
Sequence: AGNKPFNKQQAEPRERDPQVAGLKVPPHSIEAEQSVLGGLMLDNERWDDVAERVVADDFYTRPHRHIFTEMARLQESGSPIDLITLAESLERQGQLDSVGGFAYLAELSKNTPSAANISAYADIVRERAVVREMISVANEIAEAGFDPQGRTSEDLLDLAESRVFKIAESRANKDEGPKNIADVLDATVARIEQLFQQPHDGVTGVNTGYDDLNKKTAGLQPSDLIIVAARPSMGKTTFAMNLVENAAMLQDKPVLIFSLEMPSEQIMMRSLASLSRVDQTKIRTGQLDDEDWARISGTMGILLEKRNIYIDDSSGLTPTEVRSRARRIAREHGGIGLIMIDYLQLMRVPALSDNRTLEIAEISRSLKALAKELNVPVVALSQLNRSLEQRADKRPVNSDLRESGSIEQDADLIMFIYRDEVYHENSDLKGIAEIIIGKQRNGPIGTVRLTFNGQWSRFDNYAGPQYDDE |
Proteomic databases
Expression
Induction
Slightly induced by hydroxyurea.
Interaction
Subunit
Homohexamer ring (PubMed:7989299, PubMed:30582519).
The helix loader is a DnaB6:DnaC6 complex with a cracked opening large enough to allow ssDNA into the central cavity (PubMed:30797687).
The helix loader is a DnaB6:DnaC6 complex with a cracked opening large enough to allow ssDNA into the central cavity (PubMed:30797687).
(Microbial infection) Forms a DnaB6:lambda P5 complex in the presence of ssDNA (PubMed:30582519).
Lambda P helicase loader reconfigures the DnaB hexameric ring, generating an opening large enough to permit ssDNA into the central channel (PubMed:30582519).
Lambda P helicase loader reconfigures the DnaB hexameric ring, generating an opening large enough to permit ssDNA into the central channel (PubMed:30582519).
Binary interactions
Type | Entry 1 | Entry 2 | Number of experiments | Intact | |
---|---|---|---|---|---|
BINARY | P0ACB0 | dnaA P03004 | 4 | EBI-548978, EBI-548951 | |
BINARY | P0ACB0 | dnaB P0ACB0 | 6 | EBI-548978, EBI-548978 | |
BINARY | P0ACB0 | dnaC P0AEF0 | 12 | EBI-548978, EBI-549012 | |
BINARY | P0ACB0 | dnaG P0ABS5 | 3 | EBI-548978, EBI-549259 | |
BINARY | P0ACB0 | dnaX P06710 | 2 | EBI-548978, EBI-549140 | |
BINARY | P0ACB0 | priC P23862 | 5 | EBI-548978, EBI-1117383 | |
BINARY | P0ACB0 | rep P09980 | 3 | EBI-548978, EBI-6558011 |
Protein-protein interaction databases
Structure
Family & Domains
Features
Showing features for region, domain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Region | 1-27 | Disordered | ||||
Sequence: MAGNKPFNKQQAEPRERDPQVAGLKVP | ||||||
Domain | 200-467 | SF4 helicase | ||||
Sequence: PHDGVTGVNTGYDDLNKKTAGLQPSDLIIVAARPSMGKTTFAMNLVENAAMLQDKPVLIFSLEMPSEQIMMRSLASLSRVDQTKIRTGQLDDEDWARISGTMGILLEKRNIYIDDSSGLTPTEVRSRARRIAREHGGIGLIMIDYLQLMRVPALSDNRTLEIAEISRSLKALAKELNVPVVALSQLNRSLEQRADKRPVNSDLRESGSIEQDADLIMFIYRDEVYHENSDLKGIAEIIIGKQRNGPIGTVRLTFNGQWSRFDNYAGPQ |
Domain
Loader protein DnaC alters the inter-domain and inter-subunit interactions of DnaB, inducing an open ring conformation that allows ssDNA to access the interior of the DnaB6DnaC6 ring (PubMed:30797687).
Sequence similarities
Belongs to the helicase family. DnaB subfamily.
Phylogenomic databases
Family and domain databases
Sequence
- Sequence statusComplete
- Length471
- Mass (Da)52,390
- Last updated1987-08-13 v1
- Checksum5B5ED3625A7F7DE5
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
K01174 EMBL· GenBank· DDBJ | AAA23689.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
L02312 EMBL· GenBank· DDBJ | AAA23690.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
U00006 EMBL· GenBank· DDBJ | AAC43146.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
U00096 EMBL· GenBank· DDBJ | AAC77022.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
AP009048 EMBL· GenBank· DDBJ | BAE78054.1 EMBL· GenBank· DDBJ | Genomic DNA |