ID   TOP1_VACCC              Reviewed;         314 AA.
AC   P68697; P08585;
DT   01-AUG-1988, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1988, sequence version 1.
DT   29-SEP-2021, entry version 79.
DE   RecName: Full=DNA topoisomerase 1B;
DE            Short=TopIB;
DE            EC=5.6.2.1 {ECO:0000255|PROSITE-ProRule:PRU10130};
DE   AltName: Full=DNA topoisomerase I;
DE   AltName: Full=Late protein H6;
GN   Name=TOP1; ORFNames=H6R;
OS   Vaccinia virus (strain Copenhagen) (VACV).
OC   Viruses; Varidnaviria; Bamfordvirae; Nucleocytoviricota; Pokkesviricetes;
OC   Chitovirales; Poxviridae; Chordopoxvirinae; Orthopoxvirus; Vaccinia virus.
OX   NCBI_TaxID=10249;
OH   NCBI_TaxID=9606; Homo sapiens (Human).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RX   PubMed=2219722; DOI=10.1016/0042-6822(90)90294-2;
RA   Goebel S.J., Johnson G.P., Perkus M.E., Davis S.W., Winslow J.P.,
RA   Paoletti E.;
RT   "The complete DNA sequence of vaccinia virus.";
RL   Virology 179:247-266(1990).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RA   Goebel S.J., Johnson G.P., Perkus M.E., Davis S.W., Winslow J.P.,
RA   Paoletti E.;
RT   "Appendix to 'The complete DNA sequence of vaccinia virus'.";
RL   Virology 179:517-563(1990).
CC   -!- FUNCTION: Releases the supercoiling and torsional tension of DNA
CC       introduced during the DNA replication and transcription by transiently
CC       cleaving and rejoining one strand of the DNA duplex. Introduces a
CC       single-strand break via transesterification at the specific target site
CC       5'-[CT]CCTTp site in duplex DNA. The scissile phosphodiester is
CC       attacked by the catalytic tyrosine of the enzyme, resulting in the
CC       formation of a DNA-(3'-phosphotyrosyl)-enzyme intermediate and the
CC       expulsion of a 5'-OH DNA strand. The free DNA strand then undergoes
CC       passage around the unbroken strand thus removing DNA supercoils.
CC       Finally, in the religation step, the DNA 5'-OH attacks the covalent
CC       intermediate to expel the active-site tyrosine and restore the DNA
CC       phosphodiester backbone (By similarity). {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=ATP-independent breakage of single-stranded DNA, followed by
CC         passage and rejoining.; EC=5.6.2.1; Evidence={ECO:0000255|PROSITE-
CC         ProRule:PRU10130};
CC   -!- INDUCTION: Expressed in the late phase of the viral replicative cycle.
CC   -!- SIMILARITY: Belongs to the type IB topoisomerase family. {ECO:0000305}.
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DR   EMBL; M35027; AAA48093.1; -; Genomic_DNA.
DR   PIR; G24481; QQVZH7.
DR   SMR; P68697; -.
DR   Proteomes; UP000008269; Genome.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0003917; F:DNA topoisomerase type I (single strand cut, ATP-independent) activity; IEA:UniProtKB-EC.
DR   GO; GO:0006265; P:DNA topological change; IEA:InterPro.
DR   CDD; cd00659; Topo_IB_C; 1.
DR   Gene3D; 3.30.66.10; -; 1.
DR   Gene3D; 3.90.15.10; -; 1.
DR   InterPro; IPR011010; DNA_brk_join_enz.
DR   InterPro; IPR035447; DNA_topo_I_N.
DR   InterPro; IPR001631; TopoI.
DR   InterPro; IPR018521; TopoI_AS.
DR   InterPro; IPR014711; TopoI_cat_a-hlx-sub_euk.
DR   InterPro; IPR013500; TopoI_cat_euk.
DR   InterPro; IPR015346; TopoI_N_vir.
DR   Pfam; PF01028; Topoisom_I; 1.
DR   Pfam; PF09266; VirDNA-topo-I_N; 1.
DR   PRINTS; PR00416; EUTPISMRASEI.
DR   SUPFAM; SSF55869; SSF55869; 1.
DR   SUPFAM; SSF56349; SSF56349; 1.
DR   PROSITE; PS00176; TOPOISOMERASE_I_EUK; 1.
PE   2: Evidence at transcript level;
KW   DNA-binding; Isomerase; Late protein; Reference proteome; Topoisomerase.
FT   CHAIN           1..314
FT                   /note="DNA topoisomerase 1B"
FT                   /id="PRO_0000145215"
FT   ACT_SITE        274
FT                   /note="O-(3'-phospho-DNA)-tyrosine intermediate"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU10130"
FT   SITE            168
FT                   /note="Involved in religation"
FT                   /evidence="ECO:0000250|UniProtKB:P32989"
SQ   SEQUENCE   314 AA;  36666 MW;  E76FBCFCBF259D27 CRC64;
     MRALFYKDGK LFTDNNFLNP VSDDNPAYEV LQHVKIPTHL TDVVVYEQTW EEALTRLIFV
     GSDSKGRRQY FYGKMHVQNR NAKRDRIFVR VYNVMKRINC FINKNIKKSS TDSNYQLAVF
     MLMETMFFIR FGKMKYLKEN ETVGLLTLKN KHIEISPDEI VIKFVGKDKV SHEFVVHKSN
     RLYKPLLKLT DDSSPEEFLF NKLSERKVYE CIKQFGIRIK DLRTYGVNYT FLYNFWTNVK
     SISPLPSPKK LIALTIKQTA EVVGHTPSIS KRAYMATTIL EMVKDKNFLD VVSKTTFDEF
     LSIVVDHVKS STDG