P28905 · HOLC_ECOLI
- ProteinDNA polymerase III subunit chi
- GeneholC
- StatusUniProtKB reviewed (Swiss-Prot)
- Organism
- Amino acids147 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
Part of the beta sliding clamp loading complex, which hydrolyzes ATP to load the beta clamp onto primed DNA to form the DNA replication pre-initiation complex (PubMed:2040637).
DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. This DNA polymerase also exhibits 3' to 5' exonuclease activity. Genetically identified as involved in the repair of replication forks and tolerance of the chain-terminating nucleoside analog 3' AZT (PubMed:26544712, PubMed:33582602, PubMed:34181484).
This subunit may stabilize YoaA and/or stimulate the helicase activity of YoaA (PubMed:36509145).
DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. This DNA polymerase also exhibits 3' to 5' exonuclease activity. Genetically identified as involved in the repair of replication forks and tolerance of the chain-terminating nucleoside analog 3' AZT (PubMed:26544712, PubMed:33582602, PubMed:34181484).
This subunit may stabilize YoaA and/or stimulate the helicase activity of YoaA (PubMed:36509145).
Catalytic activity
- a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1)
GO annotations
all annotations | all molecular function | virus receptor activity | dna binding | rna binding | cytoskeletal motor activity | catalytic activity | gtpase activity | structural molecule activity | transporter activity | cytoskeletal protein binding | lipid binding | cyclase activity | antioxidant activity | oxidoreductase activity | transferase activity | hydrolase activity | lyase activity | isomerase activity | ligase activity | protein tag activity | cargo receptor activity | histone binding | protein folding chaperone | translation regulator activity | nutrient reservoir activity | receptor ligand activity | molecular transducer activity | molecular adaptor activity | toxin activity | cell adhesion mediator activity | molecular function regulator activity | virus coreceptor activity | catalytic activity, acting on a protein | catalytic activity, acting on dna | catalytic activity, acting on rna | molecular carrier activity | transcription regulator activity | general transcription initiation factor activity | molecular sensor activity | molecular sequestering activity | atp-dependent activity | other molecular function | all biological process | mitotic cell cycle | cytokinesis | cytoplasmic translation | immune system process | muscle system process | circulatory system process | renal system process | respiratory system process | carbohydrate metabolic process | generation of precursor metabolites and energy | dna replication | dna repair | dna recombination | chromatin organization | dna-templated transcription | regulation of dna-templated transcription | trna metabolic process | protein folding | protein glycosylation | amino acid metabolic process | modified amino acid metabolic process | lipid metabolic process | vitamin metabolic process | sulfur compound metabolic process | intracellular protein transport | nucleocytoplasmic transport | autophagy | inflammatory response | mitochondrion organization | cytoskeleton organization | microtubule-based movement | peroxisome organization | lysosome organization | chromosome segregation | cell adhesion | establishment or maintenance of cell polarity | programmed cell death | photosynthesis | mrna metabolic process | snrna metabolic process | vesicle-mediated transport | reproductive process | digestive system process | signaling | cell differentiation | protein catabolic process | extracellular matrix organization | regulatory ncrna-mediated gene silencing | telomere organization | cell junction organization | wound healing | ribosome biogenesis | cilium organization | anatomical structure development | cell motility | nervous system process | endocrine process | protein maturation | transmembrane transport | nucleobase-containing small molecule metabolic process | hepaticobiliary system process | membrane organization | protein-containing complex assembly | cell wall organization or biogenesis | nitrogen cycle metabolic process | protein localization to plasma membrane | defense response to other organism | detoxification | meiotic nuclear division | mitotic nuclear division | mitochondrial gene expression | carbohydrate derivative metabolic process | other biological process | all cellular component | nuclear chromosome | extracellular region | extracellular space | cell wall | nucleus | nuclear envelope | nucleoplasm | chromosome | nucleolus | mitochondrion | lysosome | endosome | vacuole | peroxisome | endoplasmic reticulum | golgi apparatus | lipid droplet | microtubule organizing center | cytosol | ribosome | cytoskeleton | plasma membrane | cilium | plastid | thylakoid | external encapsulating structure | extracellular matrix | cytoplasmic vesicle | organelle | other cellular component | |||
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Aspect | Term | |
---|---|---|
Cellular Component | DNA polymerase III complex | |
Cellular Component | DNA polymerase III, clamp loader complex | |
Cellular Component | replisome | |
Molecular Function | DNA binding | |
Molecular Function | DNA-directed DNA polymerase activity | |
Biological Process | DNA replication | |
Biological Process | DNA-templated DNA replication | |
Biological Process | positive regulation of DNA-templated DNA replication initiation | |
Biological Process | response to radiation |
Keywords
- Molecular function
- Biological process
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameDNA polymerase III subunit chi
- EC number
- Alternative names
Gene names
Organism names
- Organism
- Strains
- Taxonomic lineageBacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia
Accessions
- Primary accessionP28905
- Secondary accessions
Proteomes
Subcellular Location
UniProt Annotation
GO Annotation
Phenotypes & Variants
Disruption phenotype
Knockout mutants are sensitive to high levels of chain-terminating nucleoside analog 3' azidothymidine (AZT) (PubMed:26544712, PubMed:33582602).
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 6 | Partially complements the AZT sensitivity of a knockout mutant. | ||||
Sequence: F → A | ||||||
Mutagenesis | 20 | Cannot complement the AZT sensitivity of a knockout mutant. | ||||
Sequence: A → D | ||||||
Mutagenesis | 45 | Cannot complement the AZT sensitivity of a knockout mutant. | ||||
Sequence: D → A | ||||||
Mutagenesis | 54 | Cannot complement the AZT sensitivity of a knockout mutant. | ||||
Sequence: E → A | ||||||
Mutagenesis | 57 | Cannot complement the AZT sensitivity of a knockout mutant, interacts with SSB, decreased interaction with HolD, no interaction with YoaA. | ||||
Sequence: W → A | ||||||
Mutagenesis | 64 | Cannot complement the AZT sensitivity of the knockout mutant, interacts with SSB, decreased interaction with HolD, no interaction with YoaA. | ||||
Sequence: F → A | ||||||
Mutagenesis | 117 | Cannot fully complement the AZT sensitivity of the knockout mutant. | ||||
Sequence: V → F | ||||||
Mutagenesis | 128 | Cannot fully complement the AZT sensitivity of the knockout mutant. | ||||
Sequence: R → A | ||||||
Mutagenesis | 131 | Cannot fully complement the AZT sensitivity of the knockout mutant. | ||||
Sequence: Y → L |
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000105517 | 1-147 | DNA polymerase III subunit chi | |||
Sequence: MKNATFYLLDNDTTVDGLSAVEQLVCEIAAERWRSGKRVLIACEDEKQAYRLDEALWARPAESFVPHNLAGEGPRGGAPVEIAWPQKRSSSRRDILISLRTSFADFATAFTEVVDFVPYEDSLKQLARERYKAYRVAGFNLNTATWK |
Proteomic databases
Interaction
Subunit
The DNA polymerase III holoenzyme complex contains at least 10 different subunits organized into 3 functionally essential subassemblies: the Pol III core, the beta sliding clamp processivity factor and the clamp-loading complex. The Pol III core (subunits alpha, epsilon and theta) contains the polymerase and the 3'-5' exonuclease proofreading activities (PubMed:2040637).
The polymerase is tethered to the template via the dimeric beta sliding clamp processivity factor. The clamp-loading complex (also called gamma complex) assembles the beta sliding clamp onto the primed template and plays a central role in the organization and communication at the replication fork. The clamp-loading complex contains delta, delta', psi and chi, and 3 copies of either or both of two different DnaX proteins, gamma and tau. The DNA replisome complex has a single clamp loader (3 tau and 1 each of delta, delta', psi and chi subunits) which binds 3 Pol III cores (1 core on the leading strand and 2 on the lagging strand) each with a beta sliding clamp dimer. Additional proteins in the replisome are other copies of gamma, psi (holD) and chi (this protein), SSB, DNA helicase and RNA primase (PubMed:20413500, PubMed:22157955).
The clamp loader hydrolyzes ATP to assemble the beta processivity factor onto the primed template (PubMed:2040637) and plays a central role in the organization and communication at the replication fork. The only subunit of the DNA polymerase III holoenzyme known to interact with single-stranded DNA binding protein (SSB) (PubMed:33582602).
Interacts directly with the psi subunit (holD) (PubMed:26544712, PubMed:33582602, PubMed:14717711).
Interacts directly with DNA helicase YoaA (PubMed:26544712, PubMed:33582602, PubMed:34181484, PubMed:36509145).
It binds to HolD and YoaA, but not both simultaneously (PubMed:33582602).
The polymerase is tethered to the template via the dimeric beta sliding clamp processivity factor. The clamp-loading complex (also called gamma complex) assembles the beta sliding clamp onto the primed template and plays a central role in the organization and communication at the replication fork. The clamp-loading complex contains delta, delta', psi and chi, and 3 copies of either or both of two different DnaX proteins, gamma and tau. The DNA replisome complex has a single clamp loader (3 tau and 1 each of delta, delta', psi and chi subunits) which binds 3 Pol III cores (1 core on the leading strand and 2 on the lagging strand) each with a beta sliding clamp dimer. Additional proteins in the replisome are other copies of gamma, psi (holD) and chi (this protein), SSB, DNA helicase and RNA primase (PubMed:20413500, PubMed:22157955).
The clamp loader hydrolyzes ATP to assemble the beta processivity factor onto the primed template (PubMed:2040637) and plays a central role in the organization and communication at the replication fork. The only subunit of the DNA polymerase III holoenzyme known to interact with single-stranded DNA binding protein (SSB) (PubMed:33582602).
Interacts directly with the psi subunit (holD) (PubMed:26544712, PubMed:33582602, PubMed:14717711).
Interacts directly with DNA helicase YoaA (PubMed:26544712, PubMed:33582602, PubMed:34181484, PubMed:36509145).
It binds to HolD and YoaA, but not both simultaneously (PubMed:33582602).
Binary interactions
Type | Entry 1 | Entry 2 | Number of experiments | Intact | |
---|---|---|---|---|---|
BINARY | P28905 | dnaX P06710 | 20 | EBI-549169, EBI-549140 | |
BINARY | P28905 | holB P28631 | 6 | EBI-549169, EBI-549161 | |
BINARY | P28905 | holD P28632 | 25 | EBI-549169, EBI-549176 | |
BINARY | P28905 | ssb P0AGE0 | 10 | EBI-549169, EBI-1118620 |
Protein-protein interaction databases
Structure
Sequence
- Sequence statusComplete
- Length147
- Mass (Da)16,633
- Last updated1992-12-01 v1
- Checksum7FEFFC359B28AA88
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
L04574 EMBL· GenBank· DDBJ | AAA70368.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
Z14155 EMBL· GenBank· DDBJ | CAA78524.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
U14003 EMBL· GenBank· DDBJ | AAA97156.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
U00096 EMBL· GenBank· DDBJ | AAC77216.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
AP009048 EMBL· GenBank· DDBJ | BAE78256.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
X15130 EMBL· GenBank· DDBJ | CAA33226.1 EMBL· GenBank· DDBJ | Genomic DNA |