ID   I3_VACCW                Reviewed;         269 AA.
AC   P12923; Q76ZV0;
DT   01-OCT-1989, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1989, sequence version 1.
DT   23-FEB-2022, entry version 72.
DE   RecName: Full=Protein I3;
GN   OrderedLocusNames=VACWR072; ORFNames=I3L;
OS   Vaccinia virus (strain Western Reserve) (VACV) (Vaccinia virus (strain
OS   WR)).
OC   Viruses; Varidnaviria; Bamfordvirae; Nucleocytoviricota; Pokkesviricetes;
OC   Chitovirales; Poxviridae; Chordopoxvirinae; Orthopoxvirus; Vaccinia virus.
OX   NCBI_TaxID=10254;
OH   NCBI_TaxID=9913; Bos taurus (Bovine).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=2835495; DOI=10.1128/jvi.62.6.1889-1897.1988;
RA   Schmitt J.F.C., Stunnenberg H.G.;
RT   "Sequence and transcriptional analysis of the vaccinia virus HindIII I
RT   fragment.";
RL   J. Virol. 62:1889-1897(1988).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RA   Esposito J.J., Frace A.M., Sammons S.A., Olsen-Rasmussen M., Osborne J.,
RA   Wohlhueter R.;
RT   "Sequencing of the coding region of Vaccinia-WR to an average 9-fold
RT   redundancy and an error rate of 0.16/10kb.";
RL   Submitted (FEB-2003) to the EMBL/GenBank/DDBJ databases.
RN   [3]
RP   INTERACTION WITH THE SMALL SUBUNIT OF RIBONUCLEOTIDE REDUCTASE.
RX   PubMed=7678464; DOI=10.1073/pnas.90.2.745;
RA   Davis R.E., Mathews C.K.;
RT   "Acidic C terminus of vaccinia virus DNA-binding protein interacts with
RT   ribonucleotide reductase.";
RL   Proc. Natl. Acad. Sci. U.S.A. 90:745-749(1993).
RN   [4]
RP   DNA-BINDING, AND SUBUNIT.
RX   PubMed=10419472; DOI=10.1074/jbc.274.31.21637;
RA   Tseng M., Palaniyar N., Zhang W., Evans D.H.;
RT   "DNA binding and aggregation properties of the vaccinia virus I3L gene
RT   product.";
RL   J. Biol. Chem. 274:21637-21644(1999).
RN   [5]
RP   SUBCELLULAR LOCATION, AND INDUCTION.
RX   PubMed=12719593; DOI=10.1128/jvi.77.10.6014-6028.2003;
RA   Welsch S., Doglio L., Schleich S., Krijnse Locker J.;
RT   "The vaccinia virus I3L gene product is localized to a complex endoplasmic
RT   reticulum-associated structure that contains the viral parental DNA.";
RL   J. Virol. 77:6014-6028(2003).
RN   [6]
RP   FUNCTION, AND SUBCELLULAR LOCATION.
RX   PubMed=22438556; DOI=10.1128/jvi.00206-12;
RA   Greseth M.D., Boyle K.A., Bluma M.S., Unger B., Wiebe M.S.,
RA   Soares-Martins J.A., Wickramasekera N.T., Wahlberg J., Traktman P.;
RT   "Molecular genetic and biochemical characterization of the vaccinia virus
RT   I3 protein, the replicative single-stranded DNA binding protein.";
RL   J. Virol. 86:6197-6209(2012).
RN   [7]
RP   FUNCTION.
RX   PubMed=26773382; DOI=10.1016/j.virol.2015.12.020;
RA   Harrison M.L., Desaulniers M.A., Noyce R.S., Evans D.H.;
RT   "The acidic C-terminus of vaccinia virus I3 single-strand binding protein
RT   promotes proper assembly of DNA-protein complexes.";
RL   Virology 489:212-222(2016).
CC   -!- FUNCTION: Plays an essential role in viral DNA replication. Binds to
CC       ssDNA with high affinity and localizes to cytoplasmic factories where
CC       nascent viral genomes accumulate. May disrupt loops, hairpins and other
CC       secondary structures present on ssDNA to reduce and eliminate pausing
CC       of viral DNA polymerase at specific sites during elongation.
CC       {ECO:0000269|PubMed:22438556, ECO:0000269|PubMed:26773382}.
CC   -!- SUBUNIT: Homoomultimer (Potential). Interacts with the small subunit of
CC       ribonucleotide reductase. {ECO:0000269|PubMed:10419472,
CC       ECO:0000269|PubMed:7678464}.
CC   -!- SUBCELLULAR LOCATION: Host cytoplasm {ECO:0000269|PubMed:22438556}.
CC       Note=Localizes in cytoplasmic virus factories, where it is associated
CC       with viral DNA. {ECO:0000269|PubMed:22438556}.
CC   -!- INDUCTION: Expressed in the early phase of the viral replicative cycle.
CC       {ECO:0000269|PubMed:12719593}.
CC   -!- MISCELLANEOUS: This protein is synthesized in the early as well as at
CC       the intermediate time of infection.
CC   -!- SIMILARITY: Belongs to the chordopoxvirinae I3 family. {ECO:0000305}.
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DR   EMBL; J03399; AAB59805.1; -; Genomic_DNA.
DR   EMBL; AY243312; AAO89351.1; -; Genomic_DNA.
DR   PIR; C29889; WZVZI3.
DR   RefSeq; YP_232954.1; NC_006998.1.
DR   DIP; DIP-2159N; -.
DR   MINT; P12923; -.
DR   DNASU; 3707605; -.
DR   GeneID; 3707605; -.
DR   KEGG; vg:3707605; -.
DR   Proteomes; UP000000344; Genome.
DR   GO; GO:0030430; C:host cell cytoplasm; IDA:UniProtKB.
DR   GO; GO:0003697; F:single-stranded DNA binding; IDA:UniProtKB.
DR   GO; GO:0030261; P:chromosome condensation; IEA:UniProtKB-KW.
DR   GO; GO:0039693; P:viral DNA genome replication; IDA:UniProtKB.
DR   InterPro; IPR006754; Poxvirus_I3_ssDNA-bd.
DR   Pfam; PF04661; Pox_I3; 1.
DR   PIRSF; PIRSF003767; VAC_I3L; 1.
PE   1: Evidence at protein level;
KW   DNA condensation; DNA-binding; Early protein; Host cytoplasm;
KW   Reference proteome.
FT   CHAIN           1..269
FT                   /note="Protein I3"
FT                   /id="PRO_0000099573"
SQ   SEQUENCE   269 AA;  29997 MW;  BBE1ABC55D338810 CRC64;
     MSKVIKKRVE TSPRPTASSD SLQTCAGVIE YAKSISKSNA KCIEYVTLNA SQYANCSSIS
     IKLTDSLSSQ MTSTFIMLEG ETKLYKNKSK QDRSDGYFLK IKVTAASPML YQLLEAVYGN
     IKHKERIPNS LHSLSVETIT EKTFKDESIF INKLNGAMVE YVSTGESSIL RSIEGELESL
     SKRERQLAKA IITPVVFYRS GTETKITFAL KKLIIDREVV ANVIGLSGDS ERVSMTENVE
     EDLARNLGLV DIDDEYDEDS DKEKPIFNV