ID   LEXA_PELUB              Reviewed;         225 AA.
AC   Q4FM55;
DT   15-JAN-2008, integrated into UniProtKB/Swiss-Prot.
DT   30-AUG-2005, sequence version 1.
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=SAR11_0921;
OS   Pelagibacter ubique (strain HTCC1062).
OC   Bacteria; Proteobacteria; Alphaproteobacteria; Pelagibacterales;
OC   Pelagibacteraceae; Candidatus Pelagibacter.
OX   NCBI_TaxID=335992;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=HTCC1062;
RX   PubMed=16109880; DOI=10.1126/science.1114057;
RA   Giovannoni S.J., Tripp H.J., Givan S., Podar M., Vergin K.L., Baptista D.,
RA   Bibbs L., Eads J., Richardson T.H., Noordewier M., Rappe M.S., Short J.M.,
RA   Carrington J.C., Mathur E.J.;
RT   "Genome streamlining in a cosmopolitan oceanic bacterium.";
RL   Science 309:1242-1245(2005).
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; CP000084; AAZ21734.1; -; Genomic_DNA.
DR   RefSeq; WP_006997000.1; NC_007205.1.
DR   AlphaFoldDB; Q4FM55; -.
DR   SMR; Q4FM55; -.
DR   STRING; 335992.SAR11_0921; -.
DR   MEROPS; S24.001; -.
DR   EnsemblBacteria; AAZ21734; AAZ21734; SAR11_0921.
DR   GeneID; 66295414; -.
DR   KEGG; pub:SAR11_0921; -.
DR   eggNOG; COG1974; Bacteria.
DR   HOGENOM; CLU_066192_45_2_5; -.
DR   OMA; HVWLLPH; -.
DR   OrthoDB; 1933795at2; -.
DR   Proteomes; UP000002528; 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..225
FT                   /note="LexA repressor"
FT                   /id="PRO_1000001315"
FT   DNA_BIND        26..46
FT                   /note="H-T-H motif"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        146
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   ACT_SITE        184
FT                   /note="For autocatalytic cleavage activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
FT   SITE            111..112
FT                   /note="Cleavage; by autolysis"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00015"
SQ   SEQUENCE   225 AA;  24905 MW;  69E64C1D683121DB CRC64;
     MLTKKQKNLL LFINKKLRAS GVSPSYEEMK DSLNLKSKSG IHRLISALEE RGFIRRLAHK
     ARALEVIKLP ETASANDIYN SFSPSVIKGG LDTENTNLNE MEIPVLGSIA AGTPVEAIQN
     EVSRIPLPSN LEKNGQYFGL KVQGDSMIEA GINEGDTVII KRSDTADNGK IVVALIDEHE
     AMLKRIRRKG KTVALESANR NYETKIFGPD RVKVQGVLVS LYRNF