Reviewed, UniProtKB/Swiss-Prot O69315 (BGAL_THETH)

Names and origin

Protein names	Recommended name:     Beta-galactosidase       Short name=Beta-gal     EC=3.2.1.23 Alternative name(s):     Lactase
Organism	Thermus thermophilus
Taxonomic identifier	274 [NCBI]
Taxonomic lineage	Bacteria › Deinococcus-Thermus › Deinococci › Thermales › Thermaceae › Thermus

Protein attributes

Sequence length	645 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Catalytic activity	Hydrolysis of terminal non-reducing beta-D-galactose residues in beta-D-galactosides.
Enzyme regulation	Inhibited by Cu2+ and Fe2+, and moderately activated by divalent cations such as Co2+, Mn2+ and Zn2+. Considerably activated by dithiothreitol, beta-mercaptoethanol and cysteine. Ref.1
Subunit structure	Homotrimer. Ref.1 Ref.2
Miscellaneous	The trimeric structure is essential to exhibit high enzymatic activity.
Sequence similarities	Belongs to the glycosyl hydrolase 42 family.
biophysicochemical properties	Kinetic parameters: KM=19 mM for lactose (at pH 6.5 and at 70 degrees Celsius) KM=5.9 mM for o-nitrophenyl beta-D-galactopyranoside (at pH 6.5 and at 70 degrees Celsius) pH dependence: Optimum pH is 6.5. No activity is detected at pH below 4.5. Temperature dependence: Optimum temperature is 70 degrees Celsius. It retains more than 75% of activity after incubation at 85 degrees Celsius and the half-life at 90 degrees Celsius is 1 hour. Thermostable.

Ontologies

Keywords
Ligand	Metal-binding Zinc
Molecular function	Glycosidase Hydrolase
Technical term	3D-structure Direct protein sequencing
Gene Ontology (GO)
Biological process	carbohydrate metabolic process Inferred from electronic annotation. Source: InterPro
Molecular function	beta-galactosidase activity Inferred from electronic annotation. Source: EC zinc ion binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 645	645	Beta-galactosidase		PRO_0000367028
Regions
	Region	360 – 363	4	Substrate binding
Sites
	Active site	141	1	Proton donor
	Active site	312	1	Nucleophile
	Metal binding	106	1	Zinc
	Metal binding	150	1	Zinc
	Metal binding	152	1	Zinc
	Metal binding	155	1	Zinc
	Binding site	102	1	Substrate
	Binding site	140	1	Substrate
	Binding site	320	1	Substrate

Sequences

	Sequence		Length	Mass (Da)
	O69315-1 [UniParc]. Last modified August 1, 1998. Version 1. Checksum: 60FAE1EC1923C6C8	FASTA	645	72,824
	10 20 30 40 50 60 MLGVCYYPEH WPKERWKEDA RRMREAGLSH VRIGEFAWAL LEPEPGRLEW GWLDEAIATL 70 80 90 100 110 120 AAEGLKVVLG TPTATPPKWL VDRYPEILPV DREGRRRRFG GRRHYCFSSP VYREEARRIV 130 140 150 160 170 180 TLLAERYGGL EAVAGFQTDN EYGCHDTVRC YCPRCQEAFR GWLEARYGTI EALNEAWGTA 190 200 210 220 230 240 FWSQRYRSFA EVELPHLTVA EPNPSHLLDY YRFASDQVRA FNRLQVEILR AHAPGKFVTH 250 260 270 280 290 300 NFMGFFTDLD AFALAQDLDF ASWDSYPLGF TDLMPLPPEE KLRYARTGHP DVAAFHHDLY 310 320 330 340 350 360 RGVGRGRFWV MEQQPGPVNW APHNPSPAPG MVRLWTWEAL AHGAEVVSYF RWRQAPFAQE 370 380 390 400 410 420 QMHAGLHRPD SAPDQGFFEA KRVAEELAAL ALPPVAQAPV ALVFDYEAAW IYEVQPQGAE 430 440 450 460 470 480 WSYLGLVYLF YSALRRLGLD VDVVPPGASL RGYAFAVVPS LPIVREEALE AFREAEGPVL 490 500 510 520 530 540 FGPRSGSKTE TFQIPKELPP GPLQALLPLK VVRVESLPPG LLEVAEGALG RFPLGLWREW 550 560 570 580 590 600 VEAPLKPLLT FQDGKGALYR EGRYLYLAAW PSPELAGRLL SALAAEAGLK VLSLPEGLRL 610 620 630 640 RRRGTWVFAF NYGPEAVEAP ASEGARFLLG SRRVGPYDLA VWEEA

References

[1]

"Thermostable beta-galactosidase from an extreme thermophile, Thermus sp. A4: enzyme purification and characterization, and gene cloning and sequencing." Ohtsu N., Motoshima H., Goto K., Tsukasaki F., Matsuzawa H. Biosci. Biotechnol. Biochem. 62:1539-1545(1998) [PubMed: 9757561] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA], PROTEIN SEQUENCE OF 1-15, BIOPHYSICOCHEMICAL PROPERTIES, ENZYME REGULATION, SUBUNIT. Strain: A4.

[2]

"Trimeric crystal structure of the glycoside hydrolase family 42 beta-galactosidase from Thermus thermophilus A4 and the structure of its complex with galactose." Hidaka M., Fushinobu S., Ohtsu N., Motoshima H., Matsuzawa H., Shoun H., Wakagi T. J. Mol. Biol. 322:79-91(2002) [PubMed: 12215416] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (1.6 ANGSTROMS) IN COMPLEX WITH ZINC ION AND SUBSTRATE, REACTION MECHANISM, SUBUNIT.

Cross-references

Sequence databases

EMBLGenBankDDBJ

D85027 Genomic DNA. Translation: BAA28362.1.

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1KWG	X-ray	1.60	A	1-645	[»]
1KWK	X-ray	2.20	A	1-645	[»]

SMR

O69315. Positions 1-644.

ModBase

Search...

Protein family/group databases

CAZy

GH42. Glycoside Hydrolase Family 42.

Family and domain databases

InterPro

IPR013739. Beta_Galactosidase_C.
IPR013738. Beta_Galactosidase_Trimer.
IPR013780. Glyco_hydro_13_b.
IPR003476. Glyco_hydro_42.
IPR013529. Glyco_hydro_42_N.
IPR013781. Glyco_hydro_sg_catalytic.
[Graphical view]

Gene3D

G3DSA:2.60.40.1180. Glyco_hydro_13_b. 1 hit.
G3DSA:3.20.20.80. Glyco_hydro_cat. 1 hit.

Pfam

PF02449. Glyco_hydro_42. 1 hit.
PF08533. Glyco_hydro_42C. 1 hit.
PF08532. Glyco_hydro_42M. 1 hit.
[Graphical view]

PIRSF

PIRSF001084. B-galactosidase. 1 hit.

ProtoNet

Search...

Entry information

Entry name

BGAL_THETH

Accession

Primary (citable) accession number: O69315

Entry history

Integrated into UniProtKB/Swiss-Prot:	March 24, 2009
Last sequence update:	August 1, 1998
Last modified:	June 16, 2009
This is version 42 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HAMAP (High-quality Automated and Manual Annotation of microbial Proteomes)