ID   CCDA2_ECOLX             Reviewed;          72 AA.
AC   Q46995;
DT   01-NOV-1997, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1997, sequence version 1.
DT   25-MAY-2022, entry version 50.
DE   RecName: Full=Antitoxin CcdA;
DE   AltName: Full=Protein LetA;
GN   Name=ccdA; Synonyms=letA;
OS   Escherichia coli.
OG   Plasmid TP181.
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Escherichia.
OX   NCBI_TaxID=562;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RA   Lakshmi V.V., Thomas C.M.;
RT   "Curing of the F-like plasmid TP181 by plumbagin is due to interference
RT   with both replication and maintenance functions.";
RL   Submitted (APR-1996) to the EMBL/GenBank/DDBJ databases.
CC   -!- FUNCTION: Antitoxin component of a type II toxin-antitoxin (TA) system
CC       which inhibits the post-segregational killing (PSK) of plasmid-free
CC       cells, also referred to as a plasmid addiction system. Binds to and
CC       blocks the activity of CcdB; will also remove 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 CcdB (By similarity). {ECO:0000250}.
CC   -!- SUBUNIT: Homodimer in solution and when bound to DNA. Forms a complex
CC       with toxin CcdB; the CcdA-CcdB(2) trimer is sufficient for
CC       rejuvenation, whereas maximal operon repression occurs with
CC       CcdA(2)CcdB(2) (By similarity). {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the CcdA antitoxin family. {ECO:0000305}.
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DR   EMBL; U51588; AAA96061.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q46995; -.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   InterPro; IPR009956; Post-segregation_anti-tox_CcdA.
DR   Pfam; PF07362; CcdA; 1.
PE   3: Inferred from homology;
KW   DNA-binding; Plasmid; Repressor; Toxin-antitoxin system; Transcription;
KW   Transcription regulation.
FT   CHAIN           1..72
FT                   /note="Antitoxin CcdA"
FT                   /id="PRO_0000068385"
SQ   SEQUENCE   72 AA;  8319 MW;  A3CD01240CAF4C07 CRC64;
     MKQRITVAGD SDNYQLLKAY DVNISGLVST PMQNEARRLR PERWKVANQE GMAEVARFIE
     MNGSFADENR DW