ID   LEXA_SALCH              Reviewed;         202 AA.
AC   Q57GZ0;
DT   02-AUG-2005, integrated into UniProtKB/Swiss-Prot.
DT   10-MAY-2005, sequence version 1.
DT   03-AUG-2022, entry version 101.
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=SCH_4116;
OS   Salmonella choleraesuis (strain SC-B67).
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Salmonella.
OX   NCBI_TaxID=321314;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=SC-B67;
RX   PubMed=15781495; DOI=10.1093/nar/gki297;
RA   Chiu C.-H., Tang P., Chu C., Hu S., Bao Q., Yu J., Chou Y.-Y., Wang H.-S.,
RA   Lee Y.-S.;
RT   "The genome sequence of Salmonella enterica serovar Choleraesuis, a highly
RT   invasive and resistant zoonotic pathogen.";
RL   Nucleic Acids Res. 33:1690-1698(2005).
CC   -!- FUNCTION: Represses a number of genes involved in the response to DNA
CC       damage (SOS response), including recA and lexA. Binds to the 16 bp
CC       palindromic sequence 5'-CTGTATATATATACAG-3'. In the presence of single-
CC       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; AE017220; AAX68022.1; -; Genomic_DNA.
DR   RefSeq; WP_000646079.1; NC_006905.1.
DR   AlphaFoldDB; Q57GZ0; -.
DR   SMR; Q57GZ0; -.
DR   MEROPS; S24.001; -.
DR   EnsemblBacteria; AAX68022; AAX68022; SCH_4116.
DR   KEGG; sec:SCH_4116; -.
DR   HOGENOM; CLU_066192_45_3_6; -.
DR   OMA; HVWLLPH; -.
DR   Proteomes; UP000000538; 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; cd06529; S24_LexA-like; 1.
DR   Gene3D; 1.10.10.10; -; 1.
DR   HAMAP; MF_00015; LexA; 1.
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; Repressor; SOS response; Transcription;
KW   Transcription regulation.
FT   CHAIN           1..202
FT                   /note="LexA repressor"
FT                   /id="PRO_0000170080"
FT   DNA_BIND        28..48
FT                   /note="H-T-H motif"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        119
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        156
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   SITE            84..85
FT                   /note="Cleavage; by autolysis"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
SQ   SEQUENCE   202 AA;  22305 MW;  6BC34EA11A70430C CRC64;
     MKALTARQQE VFDLIRDHIS QTGMPPTRAE IAQRLGFRSP NAAEEHLKAL ARKGVLEIVS
     GASRGIRLLQ EEEDGLPLVG RVAAGEPLLA QQHIEGHYQV DPSLFKPSAD FLLRVSGMSM
     KDIGIMDGDL LAVHKTQDVR NGQVVVARID DEVTVKRLKK QGNKVELLPE NSEFTPIVVD
     LREQSFTIEG LAVGVIRNGE WL