Cloned (Comment) | Organism |
---|---|
expression in Escherichia coli | Salmonella enterica subsp. enterica serovar Typhimurium |
expression in Escherichia coli | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
Crystallization (Comment) | Organism |
---|---|
structures of the wild type enzyme complexed with L-lyxarohydroxamate, and of the K197A mutant complexed with L-glucarate. Residue Lys 197 functions as the galactarate-specific base and His 328 functions as the L-talarate-specific base | Salmonella enterica subsp. enterica serovar Typhimurium |
three different crystal forms are grown by hanging drop vapor diffusion at room temperature: (1) selenomethionine (SeMet)-substituted wild type enzyme, (2) wild-type enzyme complexed with Mg2+ and L-lyxarohydroxamate, and (3) the K197A mutant enzyme complexed with Mg2+ and L-glucarate | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
Protein Variants | Comment | Organism |
---|---|---|
H328A | inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate | Salmonella enterica subsp. enterica serovar Typhimurium |
H328N | inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate | Salmonella enterica subsp. enterica serovar Typhimurium |
K197A | inactive mutant enzyme, the structure of the K197A mutant enzyme complexed with Mg2+ and L-glucarate is determined by molecular replacement using the SeMet-substituted STM3697 structure as the search model | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
K197A | inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate | Salmonella enterica subsp. enterica serovar Typhimurium |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.33 | - |
galactarate | pH 8.0, 25°C | Salmonella enterica subsp. enterica serovar Typhimurium | |
0.33 | - |
galactarate | pH 8.0, 25°C | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | required | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 | |
Mg2+ | required. Ligands are residues Asp226, Glu252, and Glu278 | Salmonella enterica subsp. enterica serovar Typhimurium |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Salmonella enterica subsp. enterica serovar Typhimurium | Q8ZL58 | bifunctional L-talarate/galactarate dehydratase, activites of EC 4.2.1.42 and EC 4.2.1.156 | - |
Salmonella enterica subsp. enterica serovar Typhimurium ATCC 700720 | Q8ZL58 | bifunctional L-talarate/galactarate dehydratase, activites of EC 4.2.1.42 and EC 4.2.1.156 | - |
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 | Q8ZL58 | - |
- |
Purification (Comment) | Organism |
---|---|
- |
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
galactarate | galactarate i.e. (2R,3S,4R,5S)-2,3,4,5-tetrahydroxyhexanedioate. The enzyme also catalyzes dehydration of L-talarate. The dehydration of L-talarate is accompanied by competing epimerization to galactarate. Little epimerization to L-talarate is observed in the dehydration of galactarate. On the basis of (1) structures of the wild type enzyme complexed with L-lyxarohydroxamate, an analogue of the enolate intermediate, and of the K197A mutant complexed with L-glucarate, a substrate for exchange of the R-proton, and (2) incorporation of solvent deuterium into galactarate in competition with dehydration, it is concluded that Lys197 functions as the galactarate-specific base and His328 functions as the L-talarate-specific base. The epimerization of L-talarate to galactarate that competes with dehydration can be rationalized by partitioning of the enolate intermediate between dehydration (departure of the 3-OH group catalyzed by the conjugate acid of His328) and epimerization (protonation on C2 by the conjugate acid of Lys197). Only galactarate and L-talarate are completely dehydrated by the enzyme. No other acid sugar results in detectable turnover | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 | 5-dehydro-4-deoxy-D-glucarate + H2O | - |
? | |
galactarate | - |
Salmonella enterica subsp. enterica serovar Typhimurium | (2R,3S)-2,3-dihydroxy-5-oxohexanedioate + H2O | - |
? | |
galactarate | - |
Salmonella enterica subsp. enterica serovar Typhimurium ATCC 700720 | (2R,3S)-2,3-dihydroxy-5-oxohexanedioate + H2O | - |
? |
Synonyms | Comment | Organism |
---|---|---|
STM3697 | - |
Salmonella enterica subsp. enterica serovar Typhimurium |
STM3697 | - |
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
3.6 | - |
galactarate | pH 8.0, 25°C | Salmonella enterica subsp. enterica serovar Typhimurium | |
3.6 | - |
galactarate | pH 8.0, 25°C | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
8 | - |
assay at | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
General Information | Comment | Organism |
---|---|---|
physiological function | disruption of gene STM3697 diminishes, but does not eliminate, the ability of the organism to utilize galactarate as carbon source. Disruption eliminates the ability to grow on L-talarate | Salmonella enterica subsp. enterica serovar Typhimurium |
kcat/KM Value [1/mMs-1] | kcat/KM Value Maximum [1/mMs-1] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.11 | - |
galactarate | pH 8.0, 25°C | Salmonella enterica subsp. enterica serovar Typhimurium | |
11 | - |
galactarate | pH 8.0, 25°C | Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |