ID   DPOL_ASHV               Reviewed;         877 AA.
AC   Q64898;
DT   18-MAR-2008, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   16-JUN-2009, entry version 43.
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;
OS   Artic squirrel hepatitis virus (ASHV).
OC   Viruses; Retro-transcribing viruses; Hepadnaviridae;
OC   Orthohepadnavirus.
OX   NCBI_TaxID=41952;
OH   NCBI_TaxID=30640; Sciurus carolinensis (Gray squirrel).
OH   NCBI_TaxID=34862; Spermophilus beecheyi (Beechey ground squirrel).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   MEDLINE=96256727; PubMed=8676441;
RA   Testut P., Renard C.A., Terradillos O., Vitvitski-Trepo L., Tekaia F.,
RA   Degott C., Blake J., Boyer B., Buendia M.A.;
RT   "A new hepadnavirus endemic in arctic ground squirrels in Alaska.";
RL   J. Virol. 70:4210-4219(1996).
RN   [2]
RP   REVIEW.
RX   PubMed=17206754;
RA   Beck J., Nassal M.;
RT   "Hepatitis B virus replication.";
RL   World J. Gastroenterol. 13:48-64(2007).
CC   -!- FUNCTION: Multifunctional enzyme that converts the viral RNA
CC       genome into dsDNA in viral cytoplasmic capsids. This enzyme
CC       displays a DNA polymerase activity that can copy either DNA or RNA
CC       templates, and a ribonuclease H (RNase H) activity that cleaves
CC       the RNA strand of RNA-DNA heteroduplexes in a partially processive
CC       3'- to 5'-endonucleasic mode. Neo-synthesized pregenomic RNA
CC       (pgRNA) are encapsidated together with the P protein, and reverse-
CC       transcribed inside the nucleocapsid. Initiation of reverse-
CC       transcription occurs first by binding the epsilon loop on the
CC       pgRNA genome, and is initiated by protein priming, thereby the 5'-
CC       end of (-)DNA is covalently linked to P protein. Partial (+)DNA is
CC       synthesized from the (-)DNA template and generates the relaxed
CC       circular DNA (RC-DNA) genome. After budding and infection, the RC-
CC       DNA migrates in the nucleus, and is converted into a plasmid-like
CC       covalently closed circular DNA (cccDNA). The activity of P protein
CC       does not seem to be necessary for cccDNA generation, and is
CC       presumably released from (+)DNA by host nuclear DNA repair
CC       machinery (By similarity).
CC   -!- CATALYTIC ACTIVITY: Deoxynucleoside triphosphate + DNA(n) =
CC       diphosphate + DNA(n+1).
CC   -!- CATALYTIC ACTIVITY: Endonucleolytic cleavage to 5'-
CC       phosphomonoester.
CC   -!- ENZYME REGULATION: Activated by host HSP70 and HSP40 in vitro to
CC       be able to bind the epsilon loop of the pgRNA. Because deletion of
CC       the RNase H region renders the protein partly chaperone-
CC       independent, the chaperones may be needed indirectly to releive
CC       occlusion of the RNA-binding site by this domain. Inhibited by
CC       several reverse-transcriptase inhibitors: Lamivudine, Adefovir and
CC       Entecavir (By similarity).
CC   -!- DOMAIN: Terminal protein domain (TP) is hepadnavirus-specific.
CC       Spacer domain is highly variable and separates the TP and RT
CC       domains. Polymerase/reverse-transcriptase domain (RT) and
CC       ribonuclease H domain (RH) are similar to retrovirus reverse
CC       transcriptase/RNase H (By similarity).
CC   -!- DOMAIN: The polymerase/reverse transcriptase (RT) and ribonuclease
CC       H (RH) domains are structured in five subdomains: finger, palm,
CC       thumb, connection and RNase H. Within the palm subdomain, the
CC       'primer grip' region is thought to be involved in the positioning
CC       of the primer terminus for accommodating the incoming nucleotide.
CC       The RH domain stabilizes the association of RT with primer-
CC       template (By similarity).
CC   -!- SIMILARITY: Belongs to the hepadnaviridae P protein family.
CC   -!- SIMILARITY: Contains 1 reverse transcriptase domain.
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DR   EMBL; U29144; AAB08032.1; -; Genomic_DNA.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0003887; F:DNA-directed DNA polymerase activity; IEA:UniProtKB-KW.
DR   GO; GO:0000287; F:magnesium ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0004523; F:ribonuclease H activity; IEA:EC.
DR   GO; GO:0003723; F:RNA binding; IEA:InterPro.
DR   GO; GO:0003964; F:RNA-directed DNA polymerase activity; IEA:UniProtKB-KW.
DR   GO; GO:0006278; P:RNA-dependent DNA replication; IEA:InterPro.
DR   InterPro; IPR000477; DNA_pol_RVTase.
DR   InterPro; IPR001462; DNApol_viral_C.
DR   InterPro; IPR000201; DNApol_viral_N.
DR   Pfam; PF00336; DNA_pol_viral_C; 1.
DR   Pfam; PF00242; DNA_pol_viral_N; 1.
DR   Pfam; PF00078; RVT_1; 2.
DR   ProDom; PD000814; DNApol_viral_C; 1.
DR   PROSITE; PS50878; RT_POL; 1.
PE   3: Inferred from homology;
KW   Complete proteome; DNA replication; DNA-binding;
KW   DNA-directed DNA polymerase; Endonuclease; Hydrolase; Magnesium;
KW   Metal-binding; Multifunctional enzyme; Nuclease;
KW   Nucleotidyltransferase; RNA-directed DNA polymerase; Transferase.
FT   CHAIN         1    877       Protein P.
FT                                /FTId=PRO_0000323250.
FT   DOMAIN      393    634       Reverse transcriptase.
FT   REGION        1    181       Terminal protein domain (TP) (By
FT                                similarity).
FT   REGION      182    382       Spacer (By similarity).
FT   REGION      383    723       Polymerase/reverse transcriptase domain
FT                                (RT) (By similarity).
FT   REGION      724    877       RnaseH domain (RH) (By similarity).
FT   METAL       465    465       Magnesium; catalytic (By similarity).
FT   METAL       585    585       Magnesium; catalytic (By similarity).
FT   METAL       586    586       Magnesium; catalytic (By similarity).
FT   SITE         67     67       Priming of reverse-transcription by
FT                                covalently linking the first nucleotide
FT                                of the (-)DNA (By similarity).
SQ   SEQUENCE   877 AA;  98038 MW;  F0702C2E906E1138 CRC64;
     MHPFSQLFRN IQSLGEEEVQ ELLGPPEDAL PLLAGEDLNH RVAGLNLQLP TADLDWVHQT
     NAITGLYSTQ TAKFNPEWKQ PDFPKIHLSE DLFLNYNNFC GPLTVNEKRK LKLNFPARFF
     PKATKYFPLS KGIKNNYPDF SIEHFFAAAT YLWTLWESGI LYLRKNQTTL TFKGKPYSWG
     HRQLEQHNGQ QHESHLQSRE SSSMVASSGH ILHKQHASGP SSFPTRDLPN NFFGESQKSA
     RTGGSVREKI QTNRLGFPGK SKITIGQQGS SQVSSPRSKS SNFRNQTQAN HSSWNQRHPT
     WYSTTSNTTQ SRQREETYSS DSAFKRHSPS FEHEKSEPSS SGLCGGTESL NNTGTSTFCL
     WRSFYNTEPC GAYCLHHIVS SLEDWGPCTI SGDVTIRSPR TPRRITGGVF LVDKHPHNSS
     ESRLVVDFSQ FSRGHTRVHW PKFAVLNLQA LANLLSTNLQ WLSLDVSAAF YHIPVSPAAV
     PHLLVGSPGL ERFTPSMSHT TIHGNNSKLQ TMHNLCSRHL FNSLLLLFKT YGRKLHLLAH
     PFIMGFRKLP MGVGLSPFLL AQFTSALASM VRRNFPHCVA FAYMDDLVLG ARTHEHLTAI
     YSHICSVFLD LGIHLNVAKT KWWGHHLHFM GYVITGAGIL PQDKHVQKVS TYLKSIPLNK
     PLDYKICERL TGILNYVAPF TKCGYAALLP LYQATSRTAF VFSSLYHSWL LSLYAELWPV
     ARQRGVVCSV SDATPTGWGI CTTYQLISPT GAFALPIATA DVIAACLARC WTGARLLGTD
     NSVVLSGKLT SYPWLLACVA NWILRGTSFC YVPSAANPAD LPSRGLLPAL HPVPTLRFRP
     QLSRISLWAA SPPVSPRRPV RVAWASPVQN SEPWFPP
//