Reviewed, UniProtKB/Swiss-Prot P13846 (DPOL_HHBV)

Names and origin

Protein names

Recommended name:
    Protein P
Including the following 3 domains:
    1- Recommended name:
            DNA-directed DNA polymerase
              EC=2.7.7.7
    2- Recommended name:
            RNA-directed DNA polymerase
              EC=2.7.7.49
    3- Recommended name:
            Ribonuclease H
              EC=3.1.26.4

Gene names

Name:

P

Organism

Heron hepatitis B virus (HHBV)

Taxonomic identifier

28300 [NCBI]

Taxonomic lineage

Viruses › Retro-transcribing viruses › Hepadnaviridae › Avihepadnavirus

Virus host

Ardeidae (herons) [TaxID: 8899]

Protein attributes

Sequence length	788 AA.
Sequence status	Complete.
Protein existence	Inferred from homology.

General annotation (Comments)

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 By similarity.
Catalytic activity	Deoxynucleoside triphosphate + DNA(n) = diphosphate + DNA(n+1). Endonucleolytic cleavage to 5'-phosphomonoester.
Enzyme 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 releive occlusion of the RNA-binding site by this domain.
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 By similarity. 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 By similarity.
Sequence similarities	Belongs to the hepadnaviridae P protein family. Contains 1 reverse transcriptase domain.

Ontologies

Keywords
Biological process	DNA replication
Ligand	DNA-binding Magnesium Metal-binding
Molecular function	DNA-directed DNA polymerase Endonuclease Hydrolase Nuclease Nucleotidyltransferase RNA-directed DNA polymerase Transferase
Technical term	Multifunctional enzyme
Gene Ontology (GO)
Biological process	RNA-dependent DNA replication Inferred from electronic annotation. Source: InterPro
Molecular function	DNA binding Inferred from electronic annotation. Source: UniProtKB-KW DNA-directed DNA polymerase activity Inferred from electronic annotation. Source: UniProtKB-KW RNA binding Inferred from electronic annotation. Source: InterPro RNA-directed DNA polymerase activity Inferred from electronic annotation. Source: UniProtKB-KW magnesium ion binding Inferred from electronic annotation. Source: UniProtKB-KW ribonuclease H activity Inferred from electronic annotation. Source: EC
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 788	788	Protein P		PRO_0000222332
Regions
	Domain	376 – 565	190	Reverse transcriptase
	Region	1 – 200	200	Terminal protein domain (TP) By similarity
	Region	201 – 370	170	Spacer By similarity
	Region	656 – 788	133	RnaseH domain (RH) By similarity
Sites
	Metal binding	448	1	Magnesium; catalytic By similarity
	Metal binding	515	1	Magnesium; catalytic By similarity
	Metal binding	516	1	Magnesium; catalytic By similarity
	Site	96	1	Priming of reverse-transcription by covalently linking the first nucleotide of the (-)DNA By similarity

Sequences

	Sequence		Length	Mass (Da)
	P13846-1 [UniParc]. Last modified January 1, 1990. Version 1. Checksum: FB44F38F75EADF44	FASTA	788	90,070
	10 20 30 40 50 60 MPQPLKQSLD QSRWLKEAEI KLRELENLVD SNLEDERLKP QLSMGEDVLS PEAGDPLHPN 70 80 90 100 110 120 VRAPLSHVIG ETRHDPPHLG NRDPARHKLG KLTGLYQMKG CEFNPHWKIP DISATNFSQE 130 140 150 160 170 180 IINECPSRNW KYLTPAKFWP KSISYLPVHS GVKPKYPEFQ QNHESLVNDY LNKLFEAGIL 190 200 210 220 230 240 YKRVSKHLVT FKGPYFTWEQ KHLVPQQHGA YSSKINDRQE SRRRRIITAT SSRKNDSSRI 250 260 270 280 290 300 FGAHNNGRKI SYHSTRDGSH RLSGRTSDPT SRGALAGGDS TPIGPGSTAA HPSTHHVDRR 310 320 330 340 350 360 RRQKGQGVLQ AISREPSETR RNGTTSHHRV ARCRTSSVED FTRRPFTQSK GAYPRQGTRG 370 380 390 400 410 420 TDPQGPKAHQ QEENGSYLRG NTSWPNRVTG RIFLVDKNSR NTEEARLVVD FSQFSKGKNA 430 440 450 460 470 480 MRFPKYWCPN LTTLRRILPV GMPRISLDLS QAFYHLPLAP ASSSRLAVSD GKQVYYFRKA 490 500 510 520 530 540 PMGVGLSPFL LHLFTTAIGA EIASRFNVWT FSYMDDFLLC HPSARHLNTI SHAVCTFLQE 550 560 570 580 590 600 FGIRINFDKM TPSPVTTIRF LGYEISKQHM KIEESRWNEL RTVIKKIKVG QWYDWKCIQR 610 620 630 640 650 660 FIGHLNFVLP FTKGNIEMLK PMYDACTHRV NFAFSSRYKI LLYKLTMGVC KLTLDPKVSL 670 680 690 700 710 720 PLPRVATDAT LTHGAISHIT GGSAVFTFSK VRDIHIQELL MVCLAKLMIK PRCILTDSTY 730 740 750 760 770 780 VCHRKFSKLP WHFAMYAKQL LTRLTLYYVP SKYNPADGPT RHKPPDWTAV TYTPLSKHIY IPHRLCGL

References

[1]	"Isolation and characterization of a hepatitis B virus endemic in herons." Sprengel R., Kaleta E.F., Will H. J. Virol. 62:3832-3839(1988) [PubMed: 3418788] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
[2]	"Hepatitis B virus replication." Beck J., Nassal M. World J. Gastroenterol. 13:48-64(2007) [PubMed: 17206754] [Abstract] Cited for: REVIEW.

Cross-references

Sequence databases
EMBL GenBank DDBJ	M22056 Genomic DNA. Translation: AAA45738.1.
PIR	JDVLHH. A30082.
RefSeq	NP_040998.1.
3D structure databases
SMR	P13846. Positions 371-627.
ModBase	Search...
Genome annotation databases
GeneID	2703545.
Enzyme and pathway databases
BRENDA	2.7.7.49. 306795. 2.7.7.7. 306795. 3.1.26.4. 306795.
Family and domain databases
InterPro	IPR001462. DNApol_viral_C. IPR000201. DNApol_viral_N. IPR000477. Reverse_transcriptase. [Graphical view]
Pfam	PF00336. DNA_pol_viral_C. 1 hit. PF00242. DNA_pol_viral_N. 1 hit. PF00078. RVT_1. 1 hit. [Graphical view]
PROSITE	PS50878. RT_POL. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

DPOL_HHBV

Accession

Primary (citable) accession number: P13846

Entry history

Integrated into UniProtKB/Swiss-Prot:	January 1, 1990
Last sequence update:	January 1, 1990
Last modified:	January 19, 2010
This is version 52 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

Virus (Virus annotation project)