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Literature summary extracted from

  • Yew, W.S.; Fedorov, A.A.; Fedorov, E.V.; Almo, S.C.; Gerlt, J.A.
    Evolution of enzymatic activities in the enolase superfamily: L-talarate/galactarate dehydratase from Salmonella typhimurium LT2 (2007), Biochemistry, 46, 9564-9577.
    View publication on PubMed

Cloned(Commentary)

EC Number Cloned (Comment) Organism
4.2.1.42 expression in Escherichia coli Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.42 expression in Escherichia coli Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
4.2.1.156 expression in Escherichia coli Salmonella enterica subsp. enterica serovar Typhimurium

Crystallization (Commentary)

EC Number Crystallization (Comment) Organism
4.2.1.42 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
4.2.1.42 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
4.2.1.156 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

Protein Variants

EC Number Protein Variants Comment Organism
4.2.1.42 H328A inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.42 H328N inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.42 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
4.2.1.42 K197A inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.156 H328A inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.156 H328N inactive. Mutation totally eliminates both the dehydration and epimerization activities using both L-talarate and galactarate Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.156 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]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
4.2.1.42 0.33
-
galactarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.42 0.33
-
galactarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
4.2.1.156 0.23
-
L-talarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
4.2.1.42 Mg2+ required Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
4.2.1.42 Mg2+ required. Ligands are residues Asp226, Glu252, and Glu278 Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.156 Mg2+ required. Ligands are residues Asp226, Glu252, and Glu278 Salmonella enterica subsp. enterica serovar Typhimurium

Organism

EC Number Organism UniProt Comment Textmining
4.2.1.42 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
-
4.2.1.42 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
-
4.2.1.42 Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 Q8ZL58
-
-
4.2.1.156 Salmonella enterica subsp. enterica serovar Typhimurium Q8ZL58 bifunctional L-talarate/galactarate dehydratase, activites of ECs 4.2.1.42 and 4.2.1.156
-
4.2.1.156 Salmonella enterica subsp. enterica serovar Typhimurium ATCC 700720 Q8ZL58 bifunctional L-talarate/galactarate dehydratase, activites of ECs 4.2.1.42 and 4.2.1.156
-

Purification (Commentary)

EC Number Purification (Comment) Organism
4.2.1.42
-
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
4.2.1.42 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
-
?
4.2.1.42 galactarate
-
Salmonella enterica subsp. enterica serovar Typhimurium (2R,3S)-2,3-dihydroxy-5-oxohexanedioate + H2O
-
?
4.2.1.42 galactarate
-
Salmonella enterica subsp. enterica serovar Typhimurium ATCC 700720 (2R,3S)-2,3-dihydroxy-5-oxohexanedioate + H2O
-
?
4.2.1.156 L-talarate
-
Salmonella enterica subsp. enterica serovar Typhimurium 5-dehydro-4-deoxy-D-glucarate + H2O the dehydration of L-talarate is accompanied by competing epimerization to galactarate ?
4.2.1.156 L-talarate
-
Salmonella enterica subsp. enterica serovar Typhimurium ATCC 700720 5-dehydro-4-deoxy-D-glucarate + H2O the dehydration of L-talarate is accompanied by competing epimerization to galactarate ?

Synonyms

EC Number Synonyms Comment Organism
4.2.1.42 STM3697
-
Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.42 STM3697
-
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
4.2.1.156 STM3697
-
Salmonella enterica subsp. enterica serovar Typhimurium

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
4.2.1.42 25
-
assay at Salmonella enterica subsp. enterica serovar Typhimurium str. LT2

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
4.2.1.42 3.6
-
galactarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.42 3.6
-
galactarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
4.2.1.156 2.1
-
L-talarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
4.2.1.42 8
-
assay at Salmonella enterica subsp. enterica serovar Typhimurium str. LT2

General Information

EC Number General Information Comment Organism
4.2.1.42 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
4.2.1.156 physiological function Salmonella typhimurium LT2 can utilize L-talarate as carbon source. Insertional disruption of the gene talarate dehydratase abolishes this phenotype. The disruption also diminishes, but does not eliminate, the ability of the organism to utilize galactarate as carbon source Salmonella enterica subsp. enterica serovar Typhimurium

kcat/KM [mM/s]

EC Number kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
4.2.1.42 0.11
-
galactarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium
4.2.1.42 11
-
galactarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
4.2.1.156 9.1
-
L-talarate pH 8.0, 25°C Salmonella enterica subsp. enterica serovar Typhimurium