ID   CCDB_ECO57              Reviewed;         101 AA.
AC   P62555; P05703;
DT   19-JUL-2004, integrated into UniProtKB/Swiss-Prot.
DT   19-JUL-2004, sequence version 1.
DT   25-MAY-2022, entry version 98.
DE   RecName: Full=Toxin CcdB;
DE   AltName: Full=Cytotoxic protein CcdB;
DE   AltName: Full=LynB;
DE   AltName: Full=Protein G;
DE   AltName: Full=Protein LetD;
GN   Name=ccdB; Synonyms=G, letB, letD; OrderedLocusNames=L7063, ECO57PM28;
OS   Escherichia coli O157:H7.
OG   Plasmid pO157.
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Escherichia.
OX   NCBI_TaxID=83334;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=O157:H7 / EDL933 / ATCC 700927 / EHEC;
RX   PubMed=9722640; DOI=10.1093/nar/26.18.4196;
RA   Burland V., Shao Y., Perna N.T., Plunkett G. III, Sofia H.J.,
RA   Blattner F.R.;
RT   "The complete DNA sequence and analysis of the large virulence plasmid of
RT   Escherichia coli O157:H7.";
RL   Nucleic Acids Res. 26:4196-4204(1998).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=O157:H7 / Sakai / RIMD 0509952 / EHEC;
RX   PubMed=9628576; DOI=10.1093/dnares/5.1.1;
RA   Makino K., Ishii K., Yasunaga T., Hattori M., Yokoyama K., Yatsudo H.C.,
RA   Kubota Y., Yamaichi Y., Iida T., Yamamoto K., Honda T., Han C.G.,
RA   Ohtsubo A., Kasamatsu M., Hayashi T., Kuhara S., Shinagawa H.;
RT   "Complete nucleotide sequences of 93-kb and 3.3-kb plasmids of an
RT   enterohemorrhagic Escherichia coli O157:H7 derived from Sakai outbreak.";
RL   DNA Res. 5:1-9(1998).
CC   -!- FUNCTION: Toxic component of a type II toxin-antitoxin (TA) system,
CC       functioning in plasmid maintainence. Responsible for the post-
CC       segregational killing (PSK) of plasmid-free cells, also referred to as
CC       a plasmid addiction system. Half-life of over 2 hours. Interferes with
CC       the activity of DNA gyrase, inducing it to form a covalent GyrA-DNA
CC       complex that cannot be resolved, thus promoting breakage of plasmid and
CC       chromosomal DNA. Toxicity is inhibited by labile antitoxin CcdA, which
CC       blocks the activity of CcdB; CcdA also removes bound CcdB protein from
CC       the CcdB-GyrA complex by forming a CcdA-CcdB complex, a process termed
CC       rejuvenation. Functions as a transcriptional corepressor for the ccdAB
CC       operon, repression also requires CcdA (By similarity). {ECO:0000250}.
CC   -!- SUBUNIT: Homodimer. Forms a complex with GyrA, probably a tetramer
CC       GyrA(2)CcdB(2), in which GyrA is inactive. Forms a complex with toxin
CC       CcdB; the CcdA-CcdB(2) trimer is sufficient for rejuvenation, whereas
CC       maximal operon repression occurs with CcdA(2)CcdB(2) (By similarity).
CC       {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the CcdB toxin family. {ECO:0000305}.
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DR   EMBL; AF074613; AAC70131.1; -; Genomic_DNA.
DR   EMBL; AB011549; BAA31785.1; -; Genomic_DNA.
DR   RefSeq; NP_052635.1; NC_002128.1.
DR   RefSeq; WP_001159868.1; NZ_SDVX01000002.1.
DR   AlphaFoldDB; P62555; -.
DR   SMR; P62555; -.
DR   STRING; 155864.EDL933_p0059; -.
DR   EnsemblBacteria; AAC70131; AAC70131; Z_L7063.
DR   EnsemblBacteria; BAA31785; BAA31785; BAA31785.
DR   GeneID; 1789728; -.
DR   KEGG; ece:Z_L7063; -.
DR   KEGG; ecs:pO157p29; -.
DR   PATRIC; fig|386585.9.peg.32; -.
DR   eggNOG; ENOG5031N2R; Bacteria.
DR   HOGENOM; CLU_158043_2_0_6; -.
DR   Proteomes; UP000000558; Plasmid pO157.
DR   Proteomes; UP000002519; Plasmid pO157.
DR   GO; GO:0008657; F:DNA topoisomerase type II (double strand cut, ATP-hydrolyzing) inhibitor activity; IEA:InterPro.
DR   GO; GO:0006276; P:plasmid maintenance; IEA:InterPro.
DR   Gene3D; 2.30.30.110; -; 1.
DR   InterPro; IPR002712; CcdB.
DR   InterPro; IPR011067; Plasmid_toxin/cell-grow_inhib.
DR   Pfam; PF01845; CcdB; 1.
PE   3: Inferred from homology;
KW   Plasmid; Reference proteome; Repressor; Toxin-antitoxin system;
KW   Transcription; Transcription regulation.
FT   CHAIN           1..101
FT                   /note="Toxin CcdB"
FT                   /id="PRO_0000068387"
SQ   SEQUENCE   101 AA;  11707 MW;  566AF6681DFE94FE CRC64;
     MQFKVYTYKR ESRYRLFVDV QSDIIDTPGR RMVIPLASAR LLSDKVSREL YPVVHIGDES
     WRMMTTDMAS VPVSVIGEEV ADLSHRENDI KNAINLMFWG I