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Literature summary for 5.1.3.7 extracted from
- Characterization and mutational analysis of two UDP-galactose 4-epimerases in Streptococcus pneumoniae TIGR4 (2018), Biochemistry (Moscow), 83, 37-44 .
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene galEsp2 or galE-2, sequence comparisons, recombinant expression of His-tagged wild-type and mutant enzymes in Escherichia coli strain BL21(DE3) | Streptococcus pneumoniae |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| C300Y | site-directed mutagenesis, the mutation results in decreased activity toward UDP-GlcNAc and UDP-GalNAc | Streptococcus pneumoniae |
| K86G | site-directed mutagenesis, the mutation abolishes the ability of the enzyme to transform UDP-Glc/UDP-Gal completely | Streptococcus pneumoniae |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| UDP-N-acetyl-alpha-D-glucosamine | Streptococcus pneumoniae | - |
UDP-N-acetyl-alpha-D-galactosamine | - |
r |  |
| UDP-N-acetyl-alpha-D-glucosamine | Streptococcus pneumoniae ATCC BAA-334 / TIGR4 | - |
UDP-N-acetyl-alpha-D-galactosamine | - |
r | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Streptococcus pneumoniae | A0A0H2URG4 | - |
- |
| Streptococcus pneumoniae ATCC BAA-334 / TIGR4 | A0A0H2URG4 | - |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant His-tagged wild-type and mutant enzymes from Escherichia coli strain BL21(DE3) by nickel affinity chromatography to homogeneity | Streptococcus pneumoniae |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| 0.0185 | - |
purified recombinant enzyme GalESp2, pH 8.0, 37°C, substrate UDP-GlcNAc | Streptococcus pneumoniae |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| additional information | two genes, galEsp1 and galEsp2, are responsible for galactose metabolism in pathogenic Streptococcus pneumoniae TIGR4. Both GalESp1 and GalESp2 catalyze the epimerization of UDP-Glc/UDP-Gal, EC 5.1.3.2, but only GalESp2 catalyzes the epimerization of UDP-GlcNAc/UDP-GalNAc. Enzyme GalESp2 has a 3fold higher epimerase activity toward UDP-Glc/UDP-Gal than GalESp1. GalESp2 can convert both UDP-Glc/UDP-Gal and UDP-GlcNAc/UDP-GalNAc with conversion ratios of 29% and 28% for the UDP-Glc and UDP-GlcNAc substrates | Streptococcus pneumoniae | ? | - |
? | |
| additional information | two genes, galEsp1 and galEsp2, are responsible for galactose metabolism in pathogenic Streptococcus pneumoniae TIGR4. Both GalESp1 and GalESp2 catalyze the epimerization of UDP-Glc/UDP-Gal, EC 5.1.3.2, but only GalESp2 catalyzes the epimerization of UDP-GlcNAc/UDP-GalNAc. Enzyme GalESp2 has a 3fold higher epimerase activity toward UDP-Glc/UDP-Gal than GalESp1. GalESp2 can convert both UDP-Glc/UDP-Gal and UDP-GlcNAc/UDP-GalNAc with conversion ratios of 29% and 28% for the UDP-Glc and UDP-GlcNAc substrates | Streptococcus pneumoniae ATCC BAA-334 / TIGR4 | ? | - |
? | |
| UDP-N-acetyl-alpha-D-glucosamine | - |
Streptococcus pneumoniae | UDP-N-acetyl-alpha-D-galactosamine | - |
r | |
| UDP-N-acetyl-alpha-D-glucosamine | - |
Streptococcus pneumoniae ATCC BAA-334 / TIGR4 | UDP-N-acetyl-alpha-D-galactosamine | - |
r | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| ? | x * 38000, about, recombinant His-tagged enzyme, SDS-PAGE | Streptococcus pneumoniae |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| GalE | - |
Streptococcus pneumoniae |
| galE-2 | - |
Streptococcus pneumoniae |
| GalESp2 | - |
Streptococcus pneumoniae |
| More | cf. EC 5.1.3.2 | Streptococcus pneumoniae |
| UDP-galactose 4-epimerase | - |
Streptococcus pneumoniae |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 37 | - |
assay at | Streptococcus pneumoniae |
Temperature Stability [°C]
| Temperature Stability Minimum [°C] | Temperature Stability Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 30 | 70 | GalESp2, pH 8.0, stable at | Streptococcus pneumoniae |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 8 | - |
assay at | Streptococcus pneumoniae |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| NAD+ | the N-terminal domain harbors the conserved sequence GxxGxxG forming a modified Rossmann-fold involved in binding of the cofactor NAD+ | Streptococcus pneumoniae | |
General Information
| General Information | Comment | Organism |
|---|---|---|
| evolution | UDP-hexose 4-epimerases belong to the superfamily of short-chain/reductase having two-domain structure. The N-terminal domain with conserved sequence GxxGxxG forms a modified Rossmann-fold and is involved in binding of the cofactor NAD+, whereas a smaller domain with conserved sequence YxxxK is involved in substrate binding. Both functional motifs conserved in the SDR superfamily members are identified in GalESp1 and GalESp2. Based on its substrate specificity, GalEs can be divided into three groups. Group 1 epimerases strongly prefer non-acetylated substrates (UDP-Glc/Gal), with a corresponding Y300 residue. Group 2 epimerases can epimerize both acetylated (UDP-GlcNAc/GalNAc) and non-acetylated substrates. Group 3 epimerases show a strong preference for acetylated substrates with a corresponding G86 residue. GalESp2 is a group 2 enzyme, GalE enzymes belonging to group 2 contain KSYNNC | Streptococcus pneumoniae |
| additional information | the Lys86 residue plays a critical role in the activity and substrate specificity of GalESp2 | Streptococcus pneumoniae |
| physiological function | UDP-galactose 4-epimerase (GalE) is an essential enzyme involved in polysaccharide synthesis. GalE is a key enzyme for the processes of eukaryotic and prokaryotic protein glycosylation and the production or secretion of virulence factors in many bacterial pathogens. It is an important virulence factor in many bacterial pathogens. The two genes, galEsp1 and galEsp2, are responsible for galactose metabolism in pathogenic Streptococcus pneumoniae TIGR4. Both GalESp1 and GalESp2 catalyze the epimerization of UDP-Glc/UDP-Gal, but only GalESp2 catalyzes the epimerization of UDP-GlcNAc/UDP-GalNAc. Enzyme GalESp2 has a 3fold higher epimerase activity toward UDP-Glc/UDP-Gal than GalESp1 | Streptococcus pneumoniae |
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