Q9QMI7 · Q9QMI7_HBV
- ProteinProtein P
- GeneP
- StatusUniProtKB unreviewed (TrEMBL)
- Organism
- Amino acids843 (go to sequence)
- Protein existenceInferred from homology
- Annotation score4/5
Function
function
Multifunctional enzyme that converts the viral RNA genome into dsDNA in viral cytoplasmic capsids. This enzyme displays a DNA polymerase activity that can copy either DNA or RNA templates, and a ribonuclease H (RNase H) activity that cleaves the RNA strand of RNA-DNA heteroduplexes in a partially processive 3'- to 5'-endonucleasic mode. Neo-synthesized pregenomic RNA (pgRNA) are encapsidated together with the P protein, and reverse-transcribed inside the nucleocapsid. Initiation of reverse-transcription occurs first by binding the epsilon loop on the pgRNA genome, and is initiated by protein priming, thereby the 5'-end of -DNA is covalently linked to P protein. Partial +DNA is synthesized from the -DNA template and generates the relaxed circular DNA (RC-DNA) genome. After budding and infection, the RC-DNA migrates in the nucleus, and is converted into a plasmid-like covalently closed circular DNA (cccDNA). The activity of P protein does not seem to be necessary for cccDNA generation, and is presumably released from +DNA by host nuclear DNA repair machinery.
Miscellaneous
Hepadnaviral virions contain probably just one P protein molecule per particle.
Catalytic activity
- DNA(n) + a 2'-deoxyribonucleoside 5'-triphosphate = DNA(n+1) + diphosphate
- DNA(n) + a 2'-deoxyribonucleoside 5'-triphosphate = DNA(n+1) + diphosphate
Activity regulation
Activated by host HSP70 and HSP40 in vitro to be able to bind the epsilon loop of the pgRNA. Because deletion of the RNase H region renders the protein partly chaperone-independent, the chaperones may be needed indirectly to relieve occlusion of the RNA-binding site by this domain. Inhibited by several reverse-transcriptase inhibitors: Lamivudine, Adefovir and Entecavir.
Features
Showing features for site, binding site.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Site | 63 | Priming of reverse-transcription by covalently linking the first nucleotide of the -DNA | |||
Binding site | 429 | Mg2+ (UniProtKB | ChEBI); catalytic | |||
Binding site | 551 | Mg2+ (UniProtKB | ChEBI); catalytic | |||
Binding site | 552 | Mg2+ (UniProtKB | ChEBI); catalytic | |||
GO annotations
Aspect | Term | |
---|---|---|
Molecular Function | DNA binding | |
Molecular Function | DNA-directed DNA polymerase activity | |
Molecular Function | metal ion binding | |
Molecular Function | RNA-directed DNA polymerase activity | |
Molecular Function | RNA-DNA hybrid ribonuclease activity | |
Biological Process | DNA replication | |
Biological Process | symbiont-mediated suppression of host innate immune response | |
Biological Process | virus-mediated perturbation of host defense response |
Keywords
- Molecular function
- Biological process
- Ligand
Names & Taxonomy
Protein names
- Recommended nameProtein P
Including 3 domains:
- Recommended nameDNA-directed DNA polymerase
- EC number
- Recommended nameRNA-directed DNA polymerase
- EC number
- Recommended nameRibonuclease H
- EC number
Gene names
Organism names
- Organism
- Strain
- Taxonomic lineageViruses > Riboviria > Pararnavirae > Artverviricota > Revtraviricetes > Blubervirales > Hepadnaviridae > Orthohepadnavirus
- Virus hosts
Accessions
- Primary accessionQ9QMI7
Proteomes
Structure
Family & Domains
Features
Showing features for region, compositional bias, domain.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Region | 1-177 | Terminal protein domain (TP) | |||
Region | 178-346 | Spacer | |||
Compositional bias | 202-236 | Polar residues | |||
Region | 202-243 | Disordered | |||
Region | 347-690 | Polymerase/reverse transcriptase domain (RT) | |||
Domain | 357-600 | Reverse transcriptase | |||
Domain
Terminal protein domain (TP) is hepadnavirus-specific. Spacer domain is highly variable and separates the TP and RT domains. Polymerase/reverse-transcriptase domain (RT) and ribonuclease H domain (RH) are similar to retrovirus reverse transcriptase/RNase H.
The polymerase/reverse transcriptase (RT) and ribonuclease H (RH) domains are structured in five subdomains: finger, palm, thumb, connection and RNase H. Within the palm subdomain, the 'primer grip' region is thought to be involved in the positioning of the primer terminus for accommodating the incoming nucleotide. The RH domain stabilizes the association of RT with primer-template.
Sequence similarities
Belongs to the hepadnaviridae P protein family.
Family and domain databases
Sequence
- Sequence statusComplete
- Length843
- Mass (Da)94,495
- Last updated2000-05-01 v1
- ChecksumE21F16340EE4674F
Features
Showing features for compositional bias.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Compositional bias | 202-236 | Polar residues | |||
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
AB033556 EMBL· GenBank· DDBJ | BAA85365.1 EMBL· GenBank· DDBJ | Genomic DNA |