6-phospho-beta-galactosidase

 

This protein is involved in the first step of the subpathway that synthesises D-galactose 6-phosphate and beta-D-glucose from lactose 6-phosphate. It belongs to the glycosyl hydrolase 1 family.

 

Reference Protein and Structure

Sequence
P11546 UniProt (3.2.1.85) IPR005928 (Sequence Homologues) (PDB Homologues)
Biological species
Lactococcus lactis subsp. lactis (Bacteria) Uniprot
PDB
1pbg - THE THREE-DIMENSIONAL STRUCTURE OF 6-PHOSPHO-BETA GALACTOSIDASE FROM LACTOCOCCUS LACTIS (2.3 Å) PDBe PDBsum 1pbg
Catalytic CATH Domains
3.20.20.80 CATHdb (see all for 1pbg)
Click To Show Structure

Enzyme Reaction (EC:3.2.1.85)

6-phospho-beta-D-galactoside(2-)
CHEBI:58534ChEBI
+
water
CHEBI:15377ChEBI
→
alcohol
CHEBI:30879ChEBI
+
D-galactopyranose 6-phosphate(2-)
CHEBI:91004ChEBI
Alternative enzyme names: 6-phospho-beta-D-galactosidase, Beta-D-phosphogalactoside galactohydrolase, Phospho-beta-D-galactosidase, Phospho-beta-galactosidase, 6-Phospho-beta-D-galactosidase,

Enzyme Mechanism

Introduction

This enzyme functions via a retaining mechanism in which one of the catalytic glutamate residues acts as a nucleophile and the other as a general acid/base.

Catalytic Residues Roles

UniProt PDB* (1pbg)
Glu160 Glu160A Acts as a general acid/base. proton shuttle (general acid/base)
Glu375 Glu375A Acts as a catalytic nucleophile. covalent catalysis
*PDB label guide - RESx(y)B(C) - RES: Residue Name; x: Residue ID in PDB file; y: Residue ID in PDB sequence if different from PDB file; B: PDB Chain; C: Biological Assembly Chain if different from PDB. If label is "Not Found" it means this residue is not found in the reference PDB.

Chemical Components

References

  1. Wiesmann C et al. (1995), Structure, 3, 961-968. The three-dimensional structure of 6-phospho-beta-galactosidase from Lactococcus lactis. PMID:8535789.
  2. Yu WL et al. (2013), J Biol Chem, 288, 14949-14958. Structural insights into the substrate specificity of a 6-phospho-β-glucosidase BglA-2 from Streptococcus pneumoniae TIGR4. DOI:10.1074/jbc.M113.454751. PMID:23580646.
  3. Wiesmann C et al. (1997), J Mol Biol, 269, 851-860. Crystal structures and mechanism of 6-phospho-beta-galactosidase from Lactococcus lactis. DOI:10.1006/jmbi.1997.1084. PMID:9223646.
  4. Davies G et al. (1995), Structure, 3, 853-859. Structures and mechanisms of glycosyl hydrolases. DOI:10.1016/s0969-2126(01)00220-9. PMID:8535779.

Step 1.

Download: Image, Marvin File

Catalytic Residues Roles

Residue Roles
Glu160A proton shuttle (general acid/base)
Glu375A covalent catalysis

Chemical Components

Step 1.

Contributors

Alex Gutteridge, Craig Porter, Gemma L. Holliday