ID   LEXA_THENE              Reviewed;         197 AA.
AC   O86948;
DT   27-APR-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1998, sequence version 1.
DT   03-AUG-2022, entry version 105.
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};
OS   Thermotoga neapolitana.
OC   Bacteria; Thermotogae; Thermotogales; Thermotogaceae; Thermotoga.
OX   NCBI_TaxID=2337;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=Z2706-MC24;
RX   PubMed=10390868; DOI=10.1016/s0723-2020(99)80063-0;
RA   Zverlov V.V., Schwarz W.H.;
RT   "Organization of the chromosomal region containing the genes lexA and topA
RT   in Thermotoga neapolitana. Primary structure of LexA reveals phylogenetic
RT   relevance.";
RL   Syst. Appl. Microbiol. 22:174-178(1999).
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   -!- MISCELLANEOUS: No consensus sequence similar to the SOS-box from E.coli
CC       or from B.subtilis was found upstream of the lexA gene, suggesting the
CC       presence of another target sequence specific for the Thermotogales.
CC   -!- SIMILARITY: Belongs to the peptidase S24 family. {ECO:0000255|HAMAP-
CC       Rule:MF_00015}.
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DR   EMBL; AJ007446; CAA07513.1; -; Genomic_DNA.
DR   AlphaFoldDB; O86948; -.
DR   SMR; O86948; -.
DR   MEROPS; S24.001; -.
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..197
FT                   /note="LexA repressor"
FT                   /id="PRO_0000170099"
FT   DNA_BIND        28..47
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            83..84
FT                   /note="Cleavage; by autolysis"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
SQ   SEQUENCE   197 AA;  22708 MW;  CDE332CBA1C8A1B9 CRC64;
     MKDLTAKQRS VLIFIEEFIE KNGYPPSVRE IARRFRITPR GAQLHLVALE KKGYIERKNG
     KPRAMRVTKS VKNRVPLIGE IRAGEKKEAI EYLEDYIEVP GSFLSSGYEH FLLRVKGESM
     IEEHICDGDL VLIRRQDWAQ NGDIVAAMVE GEVTLKKFFQ RGEMVELRPA NKEMSPMFFR
     ADRVKILGKV VGVFRKI