ID   BGAL_STRTR              Reviewed;        1026 AA.
AC   P23989; Q6LDR7;
DT   01-MAR-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-1992, sequence version 1.
DT   03-AUG-2022, entry version 111.
DE   RecName: Full=Beta-galactosidase;
DE            Short=Beta-gal;
DE            EC=3.2.1.23;
DE   AltName: Full=Lactase;
GN   Name=lacZ;
OS   Streptococcus thermophilus.
OC   Bacteria; Firmicutes; Bacilli; Lactobacillales; Streptococcaceae;
OC   Streptococcus.
OX   NCBI_TaxID=1308;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=A054;
RX   PubMed=1901904; DOI=10.1099/00221287-137-2-369;
RA   Schroeder C.J., Robert C., Lenzen G., McKay L.L., Mercenier A.;
RT   "Analysis of the lacZ sequences from two Streptococcus thermophilus
RT   strains: comparison with the Escherichia coli and Lactobacillus bulgaricus
RT   beta-galactosidase sequences.";
RL   J. Gen. Microbiol. 137:369-380(1991).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-108.
RX   PubMed=2644191; DOI=10.1128/jb.171.1.244-253.1989;
RA   Poolman B., Royer T.J., Mainzer S.E., Schmidt B.F.;
RT   "Lactose transport system of Streptococcus thermophilus: a hybrid protein
RT   with homology to the melibiose carrier and enzyme III of
RT   phosphoenolpyruvate-dependent phosphotransferase systems.";
RL   J. Bacteriol. 171:244-253(1989).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Hydrolysis of terminal non-reducing beta-D-galactose residues
CC         in beta-D-galactosides.; EC=3.2.1.23;
CC   -!- SIMILARITY: Belongs to the glycosyl hydrolase 2 family. {ECO:0000305}.
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DR   EMBL; M63636; AAA63532.1; -; Genomic_DNA.
DR   EMBL; M63636; AAA63533.1; -; Genomic_DNA.
DR   EMBL; M23009; AAA26911.1; -; Genomic_DNA.
DR   PIR; A49750; A49750.
DR   RefSeq; WP_011226267.1; NZ_WMLD01000001.1.
DR   AlphaFoldDB; P23989; -.
DR   SMR; P23989; -.
DR   STRING; 322159.STER_1366; -.
DR   CAZy; GH2; Glycoside Hydrolase Family 2.
DR   GeneID; 66899161; -.
DR   eggNOG; COG3250; Bacteria.
DR   OMA; WCDHGIL; -.
DR   SABIO-RK; P23989; -.
DR   GO; GO:0009341; C:beta-galactosidase complex; IEA:InterPro.
DR   GO; GO:0004565; F:beta-galactosidase activity; IEA:UniProtKB-EC.
DR   GO; GO:0030246; F:carbohydrate binding; IEA:InterPro.
DR   GO; GO:0016052; P:carbohydrate catabolic process; IEA:UniProt.
DR   Gene3D; 2.60.40.10; -; 2.
DR   Gene3D; 2.70.98.10; -; 1.
DR   InterPro; IPR004199; B-gal_small/dom_5.
DR   InterPro; IPR036156; Beta-gal/glucu_dom_sf.
DR   InterPro; IPR011013; Gal_mutarotase_sf_dom.
DR   InterPro; IPR008979; Galactose-bd-like_sf.
DR   InterPro; IPR014718; GH-type_carb-bd.
DR   InterPro; IPR006101; Glyco_hydro_2.
DR   InterPro; IPR023232; Glyco_hydro_2_AS.
DR   InterPro; IPR006103; Glyco_hydro_2_cat.
DR   InterPro; IPR023230; Glyco_hydro_2_CS.
DR   InterPro; IPR006102; Glyco_hydro_2_Ig-like.
DR   InterPro; IPR006104; Glyco_hydro_2_N.
DR   InterPro; IPR017853; Glycoside_hydrolase_SF.
DR   InterPro; IPR013783; Ig-like_fold.
DR   InterPro; IPR032312; LacZ_4.
DR   Pfam; PF02929; Bgal_small_N; 1.
DR   Pfam; PF16353; DUF4981; 1.
DR   Pfam; PF00703; Glyco_hydro_2; 1.
DR   Pfam; PF02836; Glyco_hydro_2_C; 1.
DR   Pfam; PF02837; Glyco_hydro_2_N; 1.
DR   PRINTS; PR00132; GLHYDRLASE2.
DR   SMART; SM01038; Bgal_small_N; 1.
DR   SUPFAM; SSF49303; SSF49303; 2.
DR   SUPFAM; SSF49785; SSF49785; 1.
DR   SUPFAM; SSF51445; SSF51445; 1.
DR   SUPFAM; SSF74650; SSF74650; 1.
DR   PROSITE; PS00719; GLYCOSYL_HYDROL_F2_1; 1.
DR   PROSITE; PS00608; GLYCOSYL_HYDROL_F2_2; 1.
PE   3: Inferred from homology;
KW   Glycosidase; Hydrolase.
FT   CHAIN           1..1026
FT                   /note="Beta-galactosidase"
FT                   /id="PRO_0000057676"
FT   ACT_SITE        458
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        546
FT                   /note="Nucleophile"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   1026 AA;  117046 MW;  B453AFAD68F08C98 CRC64;
     MNMTEKIQTY LNDPKIVSVN TVDAHSDHKY FESLEEFSEG EMKLRQSLNG KWKIHYAQNT
     NQVLKDFYKT EFDETDLNFI NVPGHLELQG FGSPQYVNTQ YPWDGKEFLR PPQVPQESNA
     VASYVKHFTL NDALKDKKVF ISFQGVATSI FVWVNGNFVG YSEDSFTPSE FEISDYLVEG
     DNKLAVAVYR YSTASWLEDQ DFWRLYGIFR DVYLYAIPKV HVQDLFVKGD YDYQTKAGQL
     DIDLKTVGDY EDKKIKYVLS DYEGIVTEGD ASVNGDGELS VSLENLKIKP WSAESPKLYD
     LILHVLDDDQ VVEVVPVKVG FRRFEIKDKL MLLNGKRIVF KGVNRHEFNA RTGRCITEED
     MLWDIKVMKQ HNINAVRTSH YPNQTRWYEL CDEYGLYVID EANLETHGTW QKLGLCEPSW
     NIPASEPEWL PACLDRANNM FQRDKNHASV IIWSCGNESY AGKDIADMAD YFRSVDNTRP
     VHYEGVAWCR EFDYITDIES RMYAKPADIE EYLTTGKLVD LSSVSDKHFA SGNLTNKPQK
     PYISCEYMHT MGNSGGGLQL YTDLEKYPEY QGGFIWDFID QAIYKTLPNG SEFLSYGGDW
     HDRPSDYEFC GNGIVFADRT LTPKLQTVKH LYSNIKIAVD EKSVTIKNDN LFEDLSAYTF
     LARVYEDGRK VSESEYHFDV KPGEEATFPV NFVVEASNSE QIYEVACVLR EATEWAPKGH
     EIVRGQYVVE KISTETPVKA PLNVVEGDFN IGIQGQNFSI LLSRAQNTLV SAKYNGVEFI
     EKGPKLSFTR AYTDNDRGAG YPFEMAGWKV AGNYSKVTDT QIQIEDDSVK VTYVHELPGL
     SDVEVKVTYQ VDYKGRIFVT ANYDGKAGLP NFPEFGLEFA IGSQFTNLSY YGYGAEESYR
     DKLPGAYLGR YETSVEKTFA PYLMPQESGN HYGTREFTVS DDNHNGLKFT ALNKAFEFSA
     LRNSTEQIEN ARHQYELQES DATWIKVLAA QMGVGGDDTW GAPVHDEFLL SSADSYQLSF
     MIEPLN