ID   LEXA_CLOTE              Reviewed;         200 AA.
AC   Q895H6;
DT   01-MAR-2004, integrated into UniProtKB/Swiss-Prot.
DT   01-JUN-2003, sequence version 1.
DT   03-AUG-2022, entry version 107.
DE   RecName: Full=LexA repressor {ECO:0000255|HAMAP-Rule:MF_00015};
DE            EC=3.4.21.88 {ECO:0000255|HAMAP-Rule:MF_00015};
GN   Name=lexA {ECO:0000255|HAMAP-Rule:MF_00015}; OrderedLocusNames=CTC_01298;
OS   Clostridium tetani (strain Massachusetts / E88).
OC   Bacteria; Firmicutes; Clostridia; Eubacteriales; Clostridiaceae;
OC   Clostridium.
OX   NCBI_TaxID=212717;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=Massachusetts / E88;
RX   PubMed=12552129; DOI=10.1073/pnas.0335853100;
RA   Brueggemann H., Baeumer S., Fricke W.F., Wiezer A., Liesegang H.,
RA   Decker I., Herzberg C., Martinez-Arias R., Merkl R., Henne A.,
RA   Gottschalk G.;
RT   "The genome sequence of Clostridium tetani, the causative agent of tetanus
RT   disease.";
RL   Proc. Natl. Acad. Sci. U.S.A. 100:1316-1321(2003).
CC   -!- FUNCTION: Represses a number of genes involved in the response to DNA
CC       damage (SOS response), including recA and lexA. In the presence of
CC       single-stranded DNA, RecA interacts with LexA causing an autocatalytic
CC       cleavage which disrupts the DNA-binding part of LexA, leading to
CC       derepression of the SOS regulon and eventually DNA repair.
CC       {ECO:0000255|HAMAP-Rule:MF_00015}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Hydrolysis of Ala-|-Gly bond in repressor LexA.; EC=3.4.21.88;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_00015};
CC   -!- SUBUNIT: Homodimer. {ECO:0000255|HAMAP-Rule:MF_00015}.
CC   -!- SIMILARITY: Belongs to the peptidase S24 family. {ECO:0000255|HAMAP-
CC       Rule:MF_00015}.
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DR   EMBL; AE015927; AAO35864.1; -; Genomic_DNA.
DR   RefSeq; WP_011099526.1; NC_004557.1.
DR   AlphaFoldDB; Q895H6; -.
DR   SMR; Q895H6; -.
DR   STRING; 212717.CTC_01298; -.
DR   MEROPS; S24.001; -.
DR   EnsemblBacteria; AAO35864; AAO35864; CTC_01298.
DR   GeneID; 64179091; -.
DR   KEGG; ctc:CTC_01298; -.
DR   HOGENOM; CLU_066192_45_1_9; -.
DR   OMA; HVWLLPH; -.
DR   OrthoDB; 1933795at2; -.
DR   Proteomes; UP000001412; Chromosome.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0004252; F:serine-type endopeptidase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0006281; P:DNA repair; IEA:UniProtKB-UniRule.
DR   GO; GO:0006260; P:DNA replication; IEA:UniProtKB-UniRule.
DR   GO; GO:0045892; P:negative regulation of transcription, DNA-templated; IEA:UniProtKB-UniRule.
DR   GO; GO:0006508; P:proteolysis; IEA:InterPro.
DR   GO; GO:0009432; P:SOS response; IEA:UniProtKB-UniRule.
DR   CDD; cd00090; HTH_ARSR; 1.
DR   CDD; cd06529; S24_LexA-like; 1.
DR   Gene3D; 1.10.10.10; -; 1.
DR   HAMAP; MF_00015; LexA; 1.
DR   InterPro; IPR011991; ArsR-like_HTH.
DR   InterPro; IPR006200; LexA.
DR   InterPro; IPR039418; LexA-like.
DR   InterPro; IPR036286; LexA/Signal_pep-like_sf.
DR   InterPro; IPR006199; LexA_DNA-bd_dom.
DR   InterPro; IPR006197; Peptidase_S24_LexA.
DR   InterPro; IPR015927; Peptidase_S24_S26A/B/C.
DR   InterPro; IPR036388; WH-like_DNA-bd_sf.
DR   InterPro; IPR036390; WH_DNA-bd_sf.
DR   Pfam; PF01726; LexA_DNA_bind; 1.
DR   Pfam; PF00717; Peptidase_S24; 1.
DR   PRINTS; PR00726; LEXASERPTASE.
DR   SUPFAM; SSF46785; SSF46785; 1.
DR   SUPFAM; SSF51306; SSF51306; 1.
DR   TIGRFAMs; TIGR00498; lexA; 1.
PE   3: Inferred from homology;
KW   Autocatalytic cleavage; DNA damage; DNA repair; DNA replication;
KW   DNA-binding; Hydrolase; Reference proteome; Repressor; SOS response;
KW   Transcription; Transcription regulation.
FT   CHAIN           1..200
FT                   /note="LexA repressor"
FT                   /id="PRO_0000170026"
FT   DNA_BIND        27..47
FT                   /note="H-T-H motif"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        124
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        161
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   SITE            88..89
FT                   /note="Cleavage; by autolysis"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
SQ   SEQUENCE   200 AA;  22731 MW;  CF1B46108D6EDAC5 CRC64;
     MARQNKQEAI YEFIKEQLRE KGYPPSVREI CNAVELRSTS TVHGHLKRLE EKGVIRRDPT
     KPRAIEVLEH SIMKKEMVDI PVVGTVTAGK PILAVENIED TFALPINYVR NKKQLFALKI
     KGDSMIDTGI LDGDLAIVEK NNSVLNGEIV VALLGDRATV KRFFKEKDYI RLQPENETME
     PIIVKQCEII GKVVGVYRKY