ID   TOP1E_MIMIV             Reviewed;         336 AA.
AC   Q7T6X9;
DT   13-SEP-2005, integrated into UniProtKB/Swiss-Prot.
DT   07-DEC-2004, sequence version 2.
DT   29-SEP-2021, entry version 87.
DE   RecName: Full=DNA topoisomerase 1B;
DE            Short=TopIB;
DE            EC=5.6.2.1;
DE   AltName: Full=DNA topoisomerase type IB;
GN   Name=TOP1E; OrderedLocusNames=MIMI_R194;
OS   Acanthamoeba polyphaga mimivirus (APMV).
OC   Viruses; Varidnaviria; Bamfordvirae; Nucleocytoviricota; Megaviricetes;
OC   Imitervirales; Mimiviridae; Mimivirus.
OX   NCBI_TaxID=212035;
OH   NCBI_TaxID=5757; Acanthamoeba polyphaga (Amoeba).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=Rowbotham-Bradford;
RX   PubMed=15486256; DOI=10.1126/science.1101485;
RA   Raoult D., Audic S., Robert C., Abergel C., Renesto P., Ogata H.,
RA   La Scola B., Susan M., Claverie J.-M.;
RT   "The 1.2-megabase genome sequence of Mimivirus.";
RL   Science 306:1344-1350(2004).
RN   [2]
RP   CHARACTERIZATION, AND MUTAGENESIS OF ARG-135; ARG-241; HIS-285 AND TYR-294.
RC   STRAIN=Rowbotham-Bradford;
RX   PubMed=16352556; DOI=10.1128/jvi.80.1.314-321.2006;
RA   Benarroch D., Claverie J.-M., Raoult D., Shuman S.;
RT   "Characterization of mimivirus DNA topoisomerase IB suggests horizontal
RT   gene transfer between eukaryal viruses and bacteria.";
RL   J. Virol. 80:314-321(2006).
RN   [3]
RP   IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS], AND SUBCELLULAR
RP   LOCATION.
RX   PubMed=16971431; DOI=10.1128/jvi.00940-06;
RA   Renesto P., Abergel C., Decloquement P., Moinier D., Azza S., Ogata H.,
RA   Fourquet P., Gorvel J.-P., Claverie J.-M., Raoult D.;
RT   "Mimivirus giant particles incorporate a large fraction of anonymous and
RT   unique gene products.";
RL   J. Virol. 80:11678-11685(2006).
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 a target site in duplex
CC       DNA. The scissile phosphodiester is attacked by the catalytic tyrosine
CC       of the enzyme, resulting in the formation of a DNA-(3'-phosphotyrosyl)-
CC       enzyme intermediate and the expulsion of a 5'-OH DNA strand. The free
CC       DNA strand then undergoes passage around the unbroken strand thus
CC       removing DNA supercoils. Finally, in the religation step, the DNA 5'-OH
CC       attacks the covalent intermediate to expel the active-site tyrosine and
CC       restore the DNA phosphodiester backbone (By similarity). Cleaves DNA
CC       after CCCTT sequence. {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;
CC   -!- SUBUNIT: Monomer. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Virion {ECO:0000269|PubMed:16971431}.
CC   -!- SIMILARITY: Belongs to the type IB topoisomerase family. {ECO:0000305}.
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DR   EMBL; AY653733; AAQ09581.2; -; Genomic_DNA.
DR   RefSeq; YP_003986690.1; NC_014649.1.
DR   SMR; Q7T6X9; -.
DR   PRIDE; Q7T6X9; -.
DR   GeneID; 9924801; -.
DR   KEGG; vg:9924801; -.
DR   Proteomes; UP000001134; 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; IPR014711; TopoI_cat_a-hlx-sub_euk.
DR   InterPro; IPR013500; TopoI_cat_euk.
DR   Pfam; PF01028; Topoisom_I; 1.
DR   PRINTS; PR00416; EUTPISMRASEI.
DR   SUPFAM; SSF55869; SSF55869; 1.
DR   SUPFAM; SSF56349; SSF56349; 1.
PE   1: Evidence at protein level;
KW   DNA-binding; Isomerase; Reference proteome; Topoisomerase; Virion.
FT   CHAIN           1..336
FT                   /note="DNA topoisomerase 1B"
FT                   /id="PRO_0000145212"
FT   ACT_SITE        294
FT                   /note="O-(3'-phospho-DNA)-tyrosine intermediate"
FT                   /evidence="ECO:0000250|UniProtKB:P32989"
FT   MUTAGEN         135
FT                   /note="R->A: Complete loss of supercoil relaxation activity
FT                   in vitro."
FT                   /evidence="ECO:0000269|PubMed:16352556"
FT   MUTAGEN         241
FT                   /note="R->A: Complete loss of supercoil relaxation activity
FT                   in vitro."
FT                   /evidence="ECO:0000269|PubMed:16352556"
FT   MUTAGEN         285
FT                   /note="H->A: Partial loss of supercoil relaxation activity
FT                   in vitro."
FT                   /evidence="ECO:0000269|PubMed:16352556"
FT   MUTAGEN         294
FT                   /note="Y->A: Complete loss of supercoil relaxation activity
FT                   in vitro."
FT                   /evidence="ECO:0000269|PubMed:16352556"
SQ   SEQUENCE   336 AA;  39879 MW;  3C0A8CDE8D274FAB CRC64;
     MSYDEKHLME GIYREKSGDK FIYYYFDNNE EVTTKDIERI NKLRIPPAWT NVWVARDPNS
     PIQAIGTDSK GRKQYRYNEI HIQGAEKEKF KRLYDFIKSI PKLEKAMVRD NNFPFYNKNR
     VISLMLQMVR DYNMRVGKEV YARQNKSYGI SSLRKKHVKI SPGVITLNFK GKSGQRLNYT
     IRNDFYIDGI KMLMKLEGDR LFQYISTDED GNEKIMRVND RDLNKYIQEN MGSEFTIKDF
     RTFGANLYFI QALLSETRKR TPKNRKTIKK NIANAFKSTA RQLKHTGAVS KKSYVMNYTL
     ELYQNNPEFF IEHKNDDPID FLLRILKSYR KDVLGE