ID   BLAC_CITKO              Reviewed;         294 AA.
AC   P22390;
DT   01-AUG-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-DEC-1992, sequence version 2.
DT   03-AUG-2022, entry version 84.
DE   RecName: Full=Beta-lactamase;
DE            EC=3.5.2.6;
DE   AltName: Full=Penicillinase;
DE   Flags: Precursor;
OS   Citrobacter koseri (Citrobacter diversus).
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Citrobacter.
OX   NCBI_TaxID=545;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ULA-27;
RX   PubMed=1778425; DOI=10.1016/0378-1097(91)90448-j;
RA   Perilli M., Franceschini N., Segatore B., Amicosante G., Oratore A.,
RA   Duez C., Joris B., Frere J.-M.;
RT   "Cloning and nucleotide sequencing of the gene encoding the beta-lactamase
RT   from Citrobacter diversus.";
RL   FEMS Microbiol. Lett. 67:79-84(1991).
RN   [2]
RP   PROTEIN SEQUENCE OF 28-83.
RC   STRAIN=ULA-27;
RX   PubMed=2039443; DOI=10.1042/bj2750629;
RA   Franceschini N., Amicosante G., Perilli M., Maccarrone M., Oratore A.,
RA   van Beeumen J., Frere J.-M.;
RT   "Proteolytic interconversion and N-terminal sequences of the Citrobacter
RT   diversus major beta-lactamases.";
RL   Biochem. J. 275:629-633(1991).
RN   [3]
RP   PROTEIN SEQUENCE OF 72-79.
RX   PubMed=2848500; DOI=10.1042/bj2540891;
RA   Amicosante G., Oratore A., Joris B., Galleni M., Frere J.-M.,
RA   van Beeumen J.;
RT   "Chromosome-encoded beta-lactamases of Citrobacter diversus. Interaction
RT   with beta-iodopenicillanate and labelling of the active site.";
RL   Biochem. J. 254:891-893(1988).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a beta-lactam + H2O = a substituted beta-amino acid;
CC         Xref=Rhea:RHEA:20401, ChEBI:CHEBI:15377, ChEBI:CHEBI:35627,
CC         ChEBI:CHEBI:140347; EC=3.5.2.6; Evidence={ECO:0000255|PROSITE-
CC         ProRule:PRU10101};
CC   -!- SIMILARITY: Belongs to the class-A beta-lactamase family.
CC       {ECO:0000305}.
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DR   EMBL; X62610; CAA44485.1; -; Genomic_DNA.
DR   PIR; S19006; S19006.
DR   AlphaFoldDB; P22390; -.
DR   SMR; P22390; -.
DR   SABIO-RK; P22390; -.
DR   GO; GO:0008800; F:beta-lactamase activity; IEA:UniProtKB-EC.
DR   GO; GO:0030655; P:beta-lactam antibiotic catabolic process; IEA:InterPro.
DR   GO; GO:0046677; P:response to antibiotic; IEA:UniProtKB-KW.
DR   Gene3D; 3.40.710.10; -; 1.
DR   InterPro; IPR012338; Beta-lactam/transpept-like.
DR   InterPro; IPR045155; Beta-lactam_cat.
DR   InterPro; IPR000871; Beta-lactam_class-A.
DR   InterPro; IPR023650; Beta-lactam_class-A_AS.
DR   PANTHER; PTHR35333; PTHR35333; 1.
DR   Pfam; PF13354; Beta-lactamase2; 1.
DR   PRINTS; PR00118; BLACTAMASEA.
DR   SUPFAM; SSF56601; SSF56601; 1.
DR   PROSITE; PS00146; BETA_LACTAMASE_A; 1.
PE   1: Evidence at protein level;
KW   Antibiotic resistance; Direct protein sequencing; Hydrolase; Signal.
FT   SIGNAL          1..27
FT                   /evidence="ECO:0000269|PubMed:2039443"
FT   CHAIN           28..294
FT                   /note="Beta-lactamase"
FT                   /id="PRO_0000016977"
FT   ACT_SITE        76
FT                   /note="Acyl-ester intermediate"
FT   ACT_SITE        174
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000250"
FT   BINDING         240..242
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   CONFLICT        28
FT                   /note="R -> G (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        61
FT                   /note="R -> S (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        80..83
FT                   /note="TMVA -> AMAT (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   294 AA;  31862 MW;  BF075822858C54BB CRC64;
     MFKKRGRQTV LIAAVLAFFT ASSPLLARTQ GEPTQVQQKL AALEKQSGGR LGVALINTAD
     RSQILYRGDE RFAMCSTSKT MVAAAVLKQS ETQHDILQQK MVIKKADLTN WNPVTEKYVD
     KEMTLAELSA ATLQYSDNTA MNKLLEHLGG TSNVTAFARS IGDTTFRLDR KEPELNTAIP
     GDERDTTCPL AMAKSLHKLT LGDALAGAQR AQLVEWLKGN TTGGQSIRAG LPEGWVVGDK
     TGAGDYGTTN DIAVIWPEDR APLILVTYFT QPQQDAKGRK DILAAAAKIV TEGL