ID   LEXA_ALKHC              Reviewed;         207 AA.
AC   Q9KAD3;
DT   27-APR-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2000, sequence version 1.
DT   03-AUG-2022, entry version 131.
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=BH2356;
OS   Alkalihalobacillus halodurans (strain ATCC BAA-125 / DSM 18197 / FERM 7344
OS   / JCM 9153 / C-125) (Bacillus halodurans).
OC   Bacteria; Firmicutes; Bacilli; Bacillales; Bacillaceae; Alkalihalobacillus.
OX   NCBI_TaxID=272558;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC BAA-125 / DSM 18197 / FERM 7344 / JCM 9153 / C-125;
RX   PubMed=11058132; DOI=10.1093/nar/28.21.4317;
RA   Takami H., Nakasone K., Takaki Y., Maeno G., Sasaki R., Masui N., Fuji F.,
RA   Hirama C., Nakamura Y., Ogasawara N., Kuhara S., Horikoshi K.;
RT   "Complete genome sequence of the alkaliphilic bacterium Bacillus halodurans
RT   and genomic sequence comparison with Bacillus subtilis.";
RL   Nucleic Acids Res. 28:4317-4331(2000).
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; BA000004; BAB06075.1; -; Genomic_DNA.
DR   PIR; D83944; D83944.
DR   RefSeq; WP_010898510.1; NC_002570.2.
DR   AlphaFoldDB; Q9KAD3; -.
DR   SMR; Q9KAD3; -.
DR   STRING; 272558.10174976; -.
DR   MEROPS; S24.001; -.
DR   EnsemblBacteria; BAB06075; BAB06075; BAB06075.
DR   KEGG; bha:BH2356; -.
DR   eggNOG; COG1974; Bacteria.
DR   HOGENOM; CLU_066192_45_1_9; -.
DR   OMA; HVWLLPH; -.
DR   OrthoDB; 1933795at2; -.
DR   Proteomes; UP000001258; 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..207
FT                   /note="LexA repressor"
FT                   /id="PRO_0000170006"
FT   DNA_BIND        28..48
FT                   /note="H-T-H motif"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        129
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        167
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   SITE            94..95
FT                   /note="Cleavage; by autolysis"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
SQ   SEQUENCE   207 AA;  23134 MW;  188AC8E64BCC169C CRC64;
     MSKLSRRQQE ILDYIKEEVR AKGYPPSVRE IGEAVGLASS STVHGHLSRL EKKGYIRRDP
     TKPRAIEVLD LENLASETTE AKATYIPVVG KVTAGLPITA VENVEEYFPL PEQLTANDNT
     YALRIQGDSM IEAGIFDGDL VIVRQQQTAD NGDIIVAMTE EDEATVKRFF REKDYIRLQP
     ENSTMEPIIL TTCTILGKVI GVFRTIH