ID   LEXA_THIDA              Reviewed;         200 AA.
AC   Q3SIT9;
DT   18-MAR-2008, integrated into UniProtKB/Swiss-Prot.
DT   18-MAR-2008, sequence version 2.
DT   03-AUG-2022, entry version 103.
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=Tbd_1483;
OS   Thiobacillus denitrificans (strain ATCC 25259).
OC   Bacteria; Proteobacteria; Betaproteobacteria; Nitrosomonadales;
OC   Thiobacillaceae; Thiobacillus.
OX   NCBI_TaxID=292415;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC 25259;
RX   PubMed=16452431; DOI=10.1128/jb.188.4.1473-1488.2006;
RA   Beller H.R., Chain P.S., Letain T.E., Chakicherla A., Larimer F.W.,
RA   Richardson P.M., Coleman M.A., Wood A.P., Kelly D.P.;
RT   "The genome sequence of the obligately chemolithoautotrophic, facultatively
RT   anaerobic bacterium Thiobacillus denitrificans.";
RL   J. Bacteriol. 188:1473-1488(2006).
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}.
CC   -!- SEQUENCE CAUTION:
CC       Sequence=AAZ97436.1; Type=Erroneous initiation; Evidence={ECO:0000305};
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DR   EMBL; CP000116; AAZ97436.1; ALT_INIT; Genomic_DNA.
DR   RefSeq; WP_041432518.1; NC_007404.1.
DR   AlphaFoldDB; Q3SIT9; -.
DR   SMR; Q3SIT9; -.
DR   STRING; 292415.Tbd_1483; -.
DR   MEROPS; S24.001; -.
DR   EnsemblBacteria; AAZ97436; AAZ97436; Tbd_1483.
DR   KEGG; tbd:Tbd_1483; -.
DR   eggNOG; COG1974; Bacteria.
DR   HOGENOM; CLU_066192_45_3_4; -.
DR   OrthoDB; 1933795at2; -.
DR   Proteomes; UP000008291; 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; Reference proteome; Repressor; SOS response;
KW   Transcription; Transcription regulation.
FT   CHAIN           1..200
FT                   /note="LexA repressor"
FT                   /id="PRO_0000322771"
FT   DNA_BIND        28..48
FT                   /note="H-T-H motif"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        117
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        154
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   SITE            82..83
FT                   /note="Cleavage; by autolysis"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
SQ   SEQUENCE   200 AA;  21604 MW;  2D9C5D9A0EF3715C CRC64;
     MRDLTPRQEE ILNLIREWID TTGSPPTRAE IAQHFGFSSP NAAEQHLKTL AKKGALELVS
     GASRGIRLPG GGGLAVVGQV AAGSPILAQE NIERHVQVDT ALFSPRADYL LKVRGQSMKD
     IGILDGDLLA VHRSAEARAG QVVVARIGDE VTVKRFQKRG HTVQLLPENA DFEPIVVDLK
     RQELVIEGIA VGVIRSGRSL