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Protein

Beta-galactosidase

Gene

lacZ

Organism
Escherichia coli (strain K12)
Status
Reviewed-Annotation score: -Experimental evidence at protein leveli

Functioni

Catalytic activityi

Hydrolysis of terminal non-reducing beta-D-galactose residues in beta-D-galactosides.

Cofactori

Protein has several cofactor binding sites:
  • Mg2+, Mn2+Note: Binds 2 magnesium ions per monomer. Can also use manganese.
  • Na+Note: Binds 1 sodium ion per monomer.

Activity regulationi

Inhibited by phenylethyl thio-beta-D-galactoside (PETG), isopropyl thio-beta-D-galactoside (IPTG), L-ribose, D-galactonolactone, lactose and 2-amino-D-galactose.1 Publication

Kineticsi

The values for the enzymatic assays using manganese as cofactor are very close.
  1. KM=0.04 mM for p-nitrophenyl beta-D-galactoside6 Publications
  2. KM=0.12 mM for o-nitrophenyl beta-D-galactoside6 Publications
  3. KM=0.15 mM for 2,3-dinitrophenyl beta-D-galactopyranoside6 Publications
  4. KM=0.41 mM for 2,5-dinitrophenyl beta-D-galactopyranoside6 Publications
  5. KM=11.6 mM for p-nitrophenol-alpha-L-arabinopyranoside6 Publications
  6. KM=16.9 mM for p-nitrophenol-beta-D-fucopyranoside6 Publications
  7. KM=34 µM for p-nitrophenyl beta-D-galactoside (with magnesium as cofactor and 30 degrees Celsius)6 Publications
  8. KM=140 µM for o-nitrophenyl beta-D-galactoside (with magnesium as cofactor and 30 degrees Celsius)6 Publications
  9. KM=940 µM for allolactose (with magnesium as cofactor and 30 degrees Celsius)6 Publications
  10. KM=1350 µM for lactose (with magnesium as cofactor and 30 degrees Celsius)6 Publications
  1. Vmax=30.9 µmol/min/mg enzyme with lactose as substrate (with magnesium as cofactor and 30 degrees Celsius)6 Publications
  2. Vmax=49.7 µmol/min/mg enzyme with allolactose as substrate (with magnesium as cofactor and 30 degrees Celsius)6 Publications
  3. Vmax=59.7 µmol/min/mg enzyme with p-nitrophenyl beta-D-galactoside as substrate (with magnesium as cofactor and 30 degrees Celsius)6 Publications
  4. Vmax=360 µmol/min/mg enzyme with o-nitrophenyl beta-D-galactoside as substrate (with magnesium as cofactor and 30 degrees Celsius)6 Publications

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Binding sitei103Substrate1
Metal bindingi202Sodium1
Binding sitei202Substrate1
Sitei358Transition state stabilizer1
Sitei392Transition state stabilizer1
Metal bindingi417Magnesium 11 Publication1
Metal bindingi419Magnesium 11 Publication1
Active sitei462Proton donor1 Publication1
Metal bindingi462Magnesium 11 Publication1
Binding sitei462Substrate1
Active sitei538Nucleophile1 Publication1
Metal bindingi598Magnesium 21 Publication1
Metal bindingi602Sodium; via carbonyl oxygen1
Metal bindingi605Sodium1
Binding sitei605Substrate1
Binding sitei1000Substrate1
Sitei1000Important for ensuring that an appropriate proportion of lactose is converted to allolactose1

GO - Molecular functioni

  • alkali metal ion binding Source: EcoCyc
  • beta-galactosidase activity Source: EcoCyc
  • carbohydrate binding Source: InterPro
  • identical protein binding Source: IntAct
  • magnesium ion binding Source: EcoCyc

GO - Biological processi

  • lactose catabolic process Source: CACAO

Keywordsi

Molecular functionGlycosidase, Hydrolase
LigandMagnesium, Manganese, Metal-binding, Sodium

Enzyme and pathway databases

BioCyciEcoCyc:BETAGALACTOSID-MONOMER
MetaCyc:BETAGALACTOSID-MONOMER
BRENDAi3.2.1.23 2026
SABIO-RKiP00722

Protein family/group databases

CAZyiGH2 Glycoside Hydrolase Family 2

Names & Taxonomyi

Protein namesi
Recommended name:
Beta-galactosidase (EC:3.2.1.23)
Short name:
Beta-gal
Alternative name(s):
Lactase
Gene namesi
Name:lacZ
Ordered Locus Names:b0344, JW0335
OrganismiEscherichia coli (strain K12)
Taxonomic identifieri83333 [NCBI]
Taxonomic lineageiBacteriaProteobacteriaGammaproteobacteriaEnterobacteralesEnterobacteriaceaeEscherichia
Proteomesi
  • UP000000318 Componenti: Chromosome
  • UP000000625 Componenti: Chromosome

Organism-specific databases

EcoGeneiEG10527 lacZ

Subcellular locationi

GO - Cellular componenti

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi202D → E or N: Causes a significant decrease in binding affinity in the absence of monovalent cations or in the presence of potassium ions, but only a moderate decrease in the presence of sodium ions. 1 Publication1
Mutagenesisi202D → F: Obliterates all binding and catalysis. 1 Publication1
Mutagenesisi358H → D, F, L or N: Less stable to heat than wild-type. Causes significant destabilizations of the first transition state. 1 Publication1
Mutagenesisi392H → E, F or K: Essentially inactive unless very rapid purification. Causes very large destabilizations of the transition state. 1 Publication1
Mutagenesisi462E → H: Slowly inactivates galactosidase activity by reducing the binding of magnesium. It increases binding specificity. 1 Publication1
Mutagenesisi538E → Q: 10000-fold decrease in the beta-galactosidase activity. 1 Publication1
Mutagenesisi541H → E, F or N: Poorly reactive with galactosyl substrates. Less stable to heat than wild-type. 1 Publication1
Mutagenesisi602F → A: Decreases the stability of the loop 794-804. 1 Publication1
Mutagenesisi795G → A: It forces the apoenzyme to adopt the closed rather than the open conformation. Reduces the binding affinity. 1 Publication1
Mutagenesisi798E → A or L: The catalytic efficiency is not increased, when the sodium concentration increases. 1 Publication1
Mutagenesisi798E → D or Q: Small increase of the catalytic efficiency, when the sodium concentration increases. 1 Publication1
Mutagenesisi1000W → F, G, L or T: Decreases affinity for substrate. 1 Publication1

Chemistry databases

ChEMBLiCHEMBL4603
DrugBankiDB01920 1-O-[O-Nitrophenyl]-Beta-D-Galactopyranose
DB02228 2-deoxy-2-fluoro-Beta-D-galactose
DB04382 2-Deoxy-Beta-D-Galactose
DB04155 2-Fluoro-2-Deoxy-Beta-D-Galactopyranosyl-Beta-D-Glucopyranose
DB02632 4-nitrophenyl-beta-D-galactoside
DB04116 Allolactose
DB01885 D-Galctopyranosyl-1-On
DB01862 Isopropyl beta-D-thiogalactopyranoside
DB04465 Lactose

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Initiator methionineiRemoved1 Publication
ChainiPRO_00000576502 – 1024Beta-galactosidaseAdd BLAST1023

Proteomic databases

PaxDbiP00722
PRIDEiP00722

Expressioni

Inductioni

By allolactose.1 Publication

Interactioni

Subunit structurei

Homotetramer.4 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
itself3EBI-369998,EBI-369998

GO - Molecular functioni

Protein-protein interaction databases

DIPiDIP-10081N
IntActiP00722, 76 interactors
STRINGi316407.85674486

Chemistry databases

BindingDBiP00722

Structurei

Secondary structure

11024
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details

3D structure databases

ProteinModelPortaliP00722
SMRiP00722
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP00722

Family & Domainsi

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni538 – 541Substrate binding4

Sequence similaritiesi

Belongs to the glycosyl hydrolase 2 family.Curated

Phylogenomic databases

eggNOGiENOG4105CNT Bacteria
COG3250 LUCA
HOGENOMiHOG000252443
InParanoidiP00722
KOiK01190
PhylomeDBiP00722

Family and domain databases

Gene3Di2.60.120.260, 1 hit
2.60.40.10, 2 hits
2.70.98.10, 1 hit
HAMAPiMF_01687 Beta_gal, 1 hit
InterProiView protein in InterPro
IPR004199 B-gal_small/dom_5
IPR036156 Beta-gal/glucu_dom_sf
IPR011013 Gal_mutarotase_sf_dom
IPR008979 Galactose-bd-like_sf
IPR014718 GH-type_carb-bd
IPR006101 Glyco_hydro_2
IPR023232 Glyco_hydro_2_AS
IPR023933 Glyco_hydro_2_beta_Galsidase
IPR006103 Glyco_hydro_2_cat
IPR023230 Glyco_hydro_2_CS
IPR006102 Glyco_hydro_2_Ig-like
IPR006104 Glyco_hydro_2_N
IPR017853 Glycoside_hydrolase_SF
IPR013783 Ig-like_fold
IPR032312 LacZ_4
PANTHERiPTHR10066:SF76 PTHR10066:SF76, 1 hit
PfamiView protein in Pfam
PF02929 Bgal_small_N, 1 hit
PF16353 DUF4981, 1 hit
PF00703 Glyco_hydro_2, 1 hit
PF02836 Glyco_hydro_2_C, 1 hit
PF02837 Glyco_hydro_2_N, 1 hit
PRINTSiPR00132 GLHYDRLASE2
SMARTiView protein in SMART
SM01038 Bgal_small_N, 1 hit
SUPFAMiSSF49303 SSF49303, 2 hits
SSF49785 SSF49785, 1 hit
SSF51445 SSF51445, 1 hit
SSF74650 SSF74650, 1 hit
PROSITEiView protein in PROSITE
PS00719 GLYCOSYL_HYDROL_F2_1, 1 hit
PS00608 GLYCOSYL_HYDROL_F2_2, 1 hit

Sequencei

Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

P00722-1 [UniParc]FASTAAdd to basket
« Hide
        10         20         30         40         50
MTMITDSLAV VLQRRDWENP GVTQLNRLAA HPPFASWRNS EEARTDRPSQ
60 70 80 90 100
QLRSLNGEWR FAWFPAPEAV PESWLECDLP EADTVVVPSN WQMHGYDAPI
110 120 130 140 150
YTNVTYPITV NPPFVPTENP TGCYSLTFNV DESWLQEGQT RIIFDGVNSA
160 170 180 190 200
FHLWCNGRWV GYGQDSRLPS EFDLSAFLRA GENRLAVMVL RWSDGSYLED
210 220 230 240 250
QDMWRMSGIF RDVSLLHKPT TQISDFHVAT RFNDDFSRAV LEAEVQMCGE
260 270 280 290 300
LRDYLRVTVS LWQGETQVAS GTAPFGGEII DERGGYADRV TLRLNVENPK
310 320 330 340 350
LWSAEIPNLY RAVVELHTAD GTLIEAEACD VGFREVRIEN GLLLLNGKPL
360 370 380 390 400
LIRGVNRHEH HPLHGQVMDE QTMVQDILLM KQNNFNAVRC SHYPNHPLWY
410 420 430 440 450
TLCDRYGLYV VDEANIETHG MVPMNRLTDD PRWLPAMSER VTRMVQRDRN
460 470 480 490 500
HPSVIIWSLG NESGHGANHD ALYRWIKSVD PSRPVQYEGG GADTTATDII
510 520 530 540 550
CPMYARVDED QPFPAVPKWS IKKWLSLPGE TRPLILCEYA HAMGNSLGGF
560 570 580 590 600
AKYWQAFRQY PRLQGGFVWD WVDQSLIKYD ENGNPWSAYG GDFGDTPNDR
610 620 630 640 650
QFCMNGLVFA DRTPHPALTE AKHQQQFFQF RLSGQTIEVT SEYLFRHSDN
660 670 680 690 700
ELLHWMVALD GKPLASGEVP LDVAPQGKQL IELPELPQPE SAGQLWLTVR
710 720 730 740 750
VVQPNATAWS EAGHISAWQQ WRLAENLSVT LPAASHAIPH LTTSEMDFCI
760 770 780 790 800
ELGNKRWQFN RQSGFLSQMW IGDKKQLLTP LRDQFTRAPL DNDIGVSEAT
810 820 830 840 850
RIDPNAWVER WKAAGHYQAE AALLQCTADT LADAVLITTA HAWQHQGKTL
860 870 880 890 900
FISRKTYRID GSGQMAITVD VEVASDTPHP ARIGLNCQLA QVAERVNWLG
910 920 930 940 950
LGPQENYPDR LTAACFDRWD LPLSDMYTPY VFPSENGLRC GTRELNYGPH
960 970 980 990 1000
QWRGDFQFNI SRYSQQQLME TSHRHLLHAE EGTWLNIDGF HMGIGGDDSW
1010 1020
SPSVSAEFQL SAGRYHYQLV WCQK
Length:1,024
Mass (Da):116,483
Last modified:January 23, 2007 - v2
Checksum:i9D295EF4CEF90B08
GO

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
J01636 Genomic DNA Translation: AAA24053.1
V00296 Genomic DNA Translation: CAA23573.1
U73857 Genomic DNA Translation: AAB18068.1
U00096 Genomic DNA Translation: AAC73447.1
AP009048 Genomic DNA Translation: BAE76126.1
V00295 Genomic DNA Translation: CAA23570.1
PIRiA90981 GBEC
RefSeqiNP_414878.1, NC_000913.3
WP_000177906.1, NZ_LN832404.1

Genome annotation databases

EnsemblBacteriaiAAC73447; AAC73447; b0344
BAE76126; BAE76126; BAE76126
GeneIDi945006
KEGGiecj:JW0335
eco:b0344

Similar proteinsi

Cross-referencesi

Web resourcesi

Worthington enzyme manual

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
J01636 Genomic DNA Translation: AAA24053.1
V00296 Genomic DNA Translation: CAA23573.1
U73857 Genomic DNA Translation: AAB18068.1
U00096 Genomic DNA Translation: AAC73447.1
AP009048 Genomic DNA Translation: BAE76126.1
V00295 Genomic DNA Translation: CAA23570.1
PIRiA90981 GBEC
RefSeqiNP_414878.1, NC_000913.3
WP_000177906.1, NZ_LN832404.1

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1DP0X-ray1.70A/B/C/D10-1024[»]
1F4AX-ray2.80A/B/C/D4-1024[»]
1F4HX-ray2.80A/B/C/D4-1024[»]
1HN1X-ray3.00A/B/C/D10-1024[»]
1JYNX-ray1.80A/B/C/D10-1024[»]
1JYVX-ray1.75A/B/C/D10-1024[»]
1JYWX-ray1.55A/B/C/D10-1024[»]
1JYXX-ray1.75A/B/C/D10-1024[»]
1JZ2X-ray2.10A/B/C/D2-1024[»]
1JZ3X-ray1.75A/B/C/D10-1024[»]
1JZ4X-ray2.10A/B/C/D10-1024[»]
1JZ5X-ray1.80A/B/C/D10-1024[»]
1JZ6X-ray2.10A/B/C/D10-1024[»]
1JZ7X-ray1.50A/B/C/D10-1024[»]
1JZ8X-ray1.50A/B/C/D10-1024[»]
1PX3X-ray1.60A/B/C/D10-1024[»]
1PX4X-ray1.60A/B/C/D10-1024[»]
3CZJX-ray2.05A/B/C/D10-1024[»]
3DYMX-ray2.05A/B/C/D10-1024[»]
3DYOX-ray1.80A/B/C/D10-1024[»]
3DYPX-ray1.75A/B/C/D10-1024[»]
3E1FX-ray3.001/2/3/410-1024[»]
3I3BX-ray2.20A/B/C/D10-1024[»]
3I3DX-ray2.20A/B/C/D10-1024[»]
3I3EX-ray2.10A/B/C/D10-1024[»]
3IAPX-ray2.00A/B/C/D10-1024[»]
3IAQX-ray2.70A/B/C/D10-1024[»]
3J7Helectron microscopy3.20A/B/C/D1-1024[»]
3MUYX-ray2.501/2/3/410-1024[»]
3MUZX-ray1.901/2/3/410-1024[»]
3MV0X-ray2.201/2/3/410-1024[»]
3MV1X-ray2.201/2/3/410-1024[»]
3SEPX-ray2.05A/B/C/D10-1024[»]
3T08X-ray2.00A/B/C/D10-1024[»]
3T09X-ray1.75A/B/C/D10-1024[»]
3T0AX-ray1.90A/B/C/D10-1024[»]
3T0BX-ray2.40A/B/C/D10-1024[»]
3T0DX-ray1.93A/B/C/D10-1024[»]
3T2OX-ray1.85A/B/C/D10-1024[»]
3T2PX-ray2.60A/B/C/D10-1024[»]
3T2QX-ray2.40A/B/C/D10-1024[»]
3VD3X-ray2.80A/B/C/D10-1024[»]
3VD4X-ray2.00A/B/C/D10-1024[»]
3VD5X-ray2.70A/B/C/D10-1024[»]
3VD7X-ray2.87A/B/C/D10-1024[»]
3VD9X-ray2.05A/B/C/D10-1024[»]
3VDAX-ray2.50A/B/C/D10-1024[»]
3VDBX-ray2.05A/B/C/D10-1024[»]
3VDCX-ray2.55A/B/C/D10-1024[»]
4CKDelectron microscopy13.00A/B/C/D1-1024[»]
4DUVX-ray2.10A/B/C/D10-1024[»]
4DUWX-ray2.20A/B/C/D10-1024[»]
4DUXX-ray2.30A/B/C/D10-1024[»]
4TTGX-ray1.60A/B/C/D15-1024[»]
4V40X-ray2.50A/B/C/D/E/F/G/H/I/J/K/L/M/N/O/P2-1024[»]
4V41X-ray2.50A/B/C/D/E/F/G/H/I/J/K/L/M/N/O/P2-1024[»]
4V44X-ray2.70A/B/C/D/E/F/G/H/I/J/K/L/M/N/O/P2-1024[»]
4V45X-ray2.60A/B/C/D/E/F/G/H/I/J/K/L/M/N/O/P2-1024[»]
5A1Aelectron microscopy2.20A/B/C/D3-1024[»]
6CVMelectron microscopy1.90A/B/C/D3-1023[»]
6DRVelectron microscopy2.20A/B/C/D1-1024[»]
ProteinModelPortaliP00722
SMRiP00722
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

DIPiDIP-10081N
IntActiP00722, 76 interactors
STRINGi316407.85674486

Chemistry databases

BindingDBiP00722
ChEMBLiCHEMBL4603
DrugBankiDB01920 1-O-[O-Nitrophenyl]-Beta-D-Galactopyranose
DB02228 2-deoxy-2-fluoro-Beta-D-galactose
DB04382 2-Deoxy-Beta-D-Galactose
DB04155 2-Fluoro-2-Deoxy-Beta-D-Galactopyranosyl-Beta-D-Glucopyranose
DB02632 4-nitrophenyl-beta-D-galactoside
DB04116 Allolactose
DB01885 D-Galctopyranosyl-1-On
DB01862 Isopropyl beta-D-thiogalactopyranoside
DB04465 Lactose

Protein family/group databases

CAZyiGH2 Glycoside Hydrolase Family 2

Proteomic databases

PaxDbiP00722
PRIDEiP00722

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsemblBacteriaiAAC73447; AAC73447; b0344
BAE76126; BAE76126; BAE76126
GeneIDi945006
KEGGiecj:JW0335
eco:b0344

Organism-specific databases

EchoBASEiEB0522
EcoGeneiEG10527 lacZ

Phylogenomic databases

eggNOGiENOG4105CNT Bacteria
COG3250 LUCA
HOGENOMiHOG000252443
InParanoidiP00722
KOiK01190
PhylomeDBiP00722

Enzyme and pathway databases

BioCyciEcoCyc:BETAGALACTOSID-MONOMER
MetaCyc:BETAGALACTOSID-MONOMER
BRENDAi3.2.1.23 2026
SABIO-RKiP00722

Miscellaneous databases

EvolutionaryTraceiP00722
PROiPR:P00722

Family and domain databases

Gene3Di2.60.120.260, 1 hit
2.60.40.10, 2 hits
2.70.98.10, 1 hit
HAMAPiMF_01687 Beta_gal, 1 hit
InterProiView protein in InterPro
IPR004199 B-gal_small/dom_5
IPR036156 Beta-gal/glucu_dom_sf
IPR011013 Gal_mutarotase_sf_dom
IPR008979 Galactose-bd-like_sf
IPR014718 GH-type_carb-bd
IPR006101 Glyco_hydro_2
IPR023232 Glyco_hydro_2_AS
IPR023933 Glyco_hydro_2_beta_Galsidase
IPR006103 Glyco_hydro_2_cat
IPR023230 Glyco_hydro_2_CS
IPR006102 Glyco_hydro_2_Ig-like
IPR006104 Glyco_hydro_2_N
IPR017853 Glycoside_hydrolase_SF
IPR013783 Ig-like_fold
IPR032312 LacZ_4
PANTHERiPTHR10066:SF76 PTHR10066:SF76, 1 hit
PfamiView protein in Pfam
PF02929 Bgal_small_N, 1 hit
PF16353 DUF4981, 1 hit
PF00703 Glyco_hydro_2, 1 hit
PF02836 Glyco_hydro_2_C, 1 hit
PF02837 Glyco_hydro_2_N, 1 hit
PRINTSiPR00132 GLHYDRLASE2
SMARTiView protein in SMART
SM01038 Bgal_small_N, 1 hit
SUPFAMiSSF49303 SSF49303, 2 hits
SSF49785 SSF49785, 1 hit
SSF51445 SSF51445, 1 hit
SSF74650 SSF74650, 1 hit
PROSITEiView protein in PROSITE
PS00719 GLYCOSYL_HYDROL_F2_1, 1 hit
PS00608 GLYCOSYL_HYDROL_F2_2, 1 hit
ProtoNetiSearch...

Entry informationi

Entry nameiBGAL_ECOLI
AccessioniPrimary (citable) accession number: P00722
Secondary accession number(s): Q2MC80
Entry historyiIntegrated into UniProtKB/Swiss-Prot: July 21, 1986
Last sequence update: January 23, 2007
Last modified: November 7, 2018
This is version 191 of the entry and version 2 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programProkaryotic Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

3D-structure, Complete proteome, Direct protein sequencing, Reference proteome

Documents

  1. SIMILARITY comments
    Index of protein domains and families
  2. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  3. Glycosyl hydrolases
    Classification of glycosyl hydrolase families and list of entries
  4. Escherichia coli
    Escherichia coli (strain K12): entries and cross-references to EcoGene
UniProt is an ELIXIR core data resource
Main funding by: National Institutes of Health

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