AC MF_04073; DC Protein; auto TR HAMAP; MF_04073; -; 1; level=0 XX Names: HBV_DPOL XX ID DPOL DE RecName: Full=Protein P; DE Includes: DE RecName: Full=DNA-directed DNA polymerase; DE EC=2.7.7.7; DE Includes: DE RecName: Full=RNA-directed DNA polymerase; DE EC=2.7.7.49; DE Includes: DE RecName: Full=Ribonuclease H; DE EC=3.1.26.4; GN Name=P; XX CC -!- FUNCTION: Multifunctional enzyme that converts the viral RNA genome CC into dsDNA in viral cytoplasmic capsids. This enzyme displays a DNA CC polymerase activity that can copy either DNA or RNA templates, and a CC ribonuclease H (RNase H) activity that cleaves the RNA strand of RNA- CC DNA heteroduplexes in a partially processive 3'- to 5'-endonucleasic CC mode. Neo-synthesized pregenomic RNA (pgRNA) are encapsidated together CC with the P protein, and reverse-transcribed inside the nucleocapsid. CC Initiation of reverse-transcription occurs first by binding the epsilon CC loop on the pgRNA genome, and is initiated by protein priming, thereby CC the 5'-end of (-)DNA is covalently linked to P protein. Partial (+)DNA CC is synthesized from the (-)DNA template and generates the relaxed CC circular DNA (RC-DNA) genome. After budding and infection, the RC-DNA CC migrates in the nucleus, and is converted into a plasmid-like CC covalently closed circular DNA (cccDNA). The activity of P protein does CC not seem to be necessary for cccDNA generation, and is presumably CC released from (+)DNA by host nuclear DNA repair machinery. CC -!- CATALYTIC ACTIVITY: CC Reaction=a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = CC diphosphate + DNA(n+1); Xref=Rhea:RHEA:22508, Rhea:RHEA-COMP:17339, CC Rhea:RHEA-COMP:17340, ChEBI:CHEBI:33019, ChEBI:CHEBI:61560, CC ChEBI:CHEBI:173112; EC=2.7.7.7; CC -!- CATALYTIC ACTIVITY: CC Reaction=a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = CC diphosphate + DNA(n+1); Xref=Rhea:RHEA:22508, Rhea:RHEA-COMP:17339, CC Rhea:RHEA-COMP:17340, ChEBI:CHEBI:33019, ChEBI:CHEBI:61560, CC ChEBI:CHEBI:173112; EC=2.7.7.49; CC -!- CATALYTIC ACTIVITY: CC Reaction=Endonucleolytic cleavage to 5'-phosphomonoester.; EC=3.1.26.4; CC -!- ACTIVITY REGULATION: Activated by host HSP70 and HSP40 in vitro to be CC able to bind the epsilon loop of the pgRNA. Because deletion of the CC RNase H region renders the protein partly chaperone-independent, the CC chaperones may be needed indirectly to relieve occlusion of the RNA- CC binding site by this domain. Inhibited by several reverse-transcriptase CC inhibitors: Lamivudine, Adefovir and Entecavir. CC -!- DOMAIN: Terminal protein domain (TP) is hepadnavirus-specific. Spacer CC domain is highly variable and separates the TP and RT domains. CC Polymerase/reverse-transcriptase domain (RT) and ribonuclease H domain CC (RH) are similar to retrovirus reverse transcriptase/RNase H. CC -!- DOMAIN: The polymerase/reverse transcriptase (RT) and ribonuclease H CC (RH) domains are structured in five subdomains: finger, palm, thumb, CC connection and RNase H. Within the palm subdomain, the 'primer grip' CC region is thought to be involved in the positioning of the primer CC terminus for accommodating the incoming nucleotide. The RH domain CC stabilizes the association of RT with primer-template. CC -!- MISCELLANEOUS: Hepadnaviral virions contain probably just one P protein CC molecule per particle. CC -!- SIMILARITY: Belongs to the hepadnaviridae P protein family. XX DR PROSITE; PS50878; RT_POL; 1; trigger=no DR Pfam; PF00336; DNA_pol_viral_C; 1; trigger=no DR Pfam; PF00242; DNA_pol_viral_N; 1; trigger=no DR Pfam; PF00078; RVT_1; 1; trigger=no XX KW DNA replication KW DNA-binding KW DNA-directed DNA polymerase KW Endonuclease KW Host-virus interaction KW Hydrolase KW Inhibition of host innate immune response by virus KW Inhibition of host RLR pathway by virus KW Magnesium KW Metal-binding KW Multifunctional enzyme KW Nuclease KW Nucleotidyltransferase KW RNA-directed DNA polymerase KW Transferase KW Viral immunoevasion XX GO GO:0003677; F:DNA binding GO GO:0003887; F:DNA-directed DNA polymerase activity GO GO:0046872; F:metal ion binding GO GO:0003964; F:RNA-directed DNA polymerase activity GO GO:0004523; F:RNA-DNA hybrid ribonuclease activity GO GO:0006260; P:DNA replication GO GO:0039503; P:suppression by virus of host innate immune response XX FT From: DPOL_HBVCJ (Q69028) FT DOMAIN 357..600 FT /note="Reverse transcriptase" FT REGION 1..177 FT /note="Terminal protein domain (TP)" FT REGION 178..346 FT /note="Spacer" FT REGION 347..690 FT /note="Polymerase/reverse transcriptase domain (RT)" FT BINDING 429 FT /ligand="Mg(2+)" FT /ligand_id="ChEBI:CHEBI:18420" FT /ligand_note="catalytic" FT Condition: D FT BINDING 551 FT /ligand="Mg(2+)" FT /ligand_id="ChEBI:CHEBI:18420" FT /ligand_note="catalytic" FT Condition: D FT BINDING 552 FT /ligand="Mg(2+)" FT /ligand_id="ChEBI:CHEBI:18420" FT /ligand_note="catalytic" FT Condition: D FT SITE 63 FT /note="Priming of reverse-transcription by covalently FT linking the first nucleotide of the (-)DNA" FT Condition: Y XX Size: 832-884; Related: None; Template: Q69028; Scope: Viruses; Orthohepadnavirus Fusion: Nter: None Cter: None Duplicate: None Plasmid: None Comments: None XX # Revision 1.8 2022/11/19 //