Cloned (Comment) | Organism |
---|---|
recombinant expression in Escherichia coli strain Escherichia coli BL21(DE3)CodonPlus-RIL | Thermus thermophilus |
Crystallization (Comment) | Organism |
---|---|
purified enzyme TtHICDH in quaternary complex with homoisocitrate, NADH, and Mg2+, X-ray diffraction strczure determination and analysis at 2.5 A resolution, molecular replacement using the apoform of TtHICDH, PDB ID 1X0L, at a resolution of 2.5 A | Thermus thermophilus |
Inhibitors | Comment | Organism | Structure |
---|---|---|---|
(2S,3S)-thiahomoisocitrate | - |
Thermus thermophilus |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.21 | - |
homoisocitrate | pH 8.0, 60°C, recombinant enzyme | Thermus thermophilus | |
0.29 | - |
isocitrate | pH 8.0, 60°C, recombinant enzyme | Thermus thermophilus |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | binding strutcure analysis | Thermus thermophilus |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
homoisocitrate + NAD+ | Thermus thermophilus | - |
2-oxoadipate + CO2 + NADH + H+ | - |
r | |
homoisocitrate + NAD+ | Thermus thermophilus DSM 7039 | - |
2-oxoadipate + CO2 + NADH + H+ | - |
r | |
isocitrate + NAD+ | Thermus thermophilus | - |
2-oxoglutarate + CO2 + NADH + H+ | - |
r | |
isocitrate + NAD+ | Thermus thermophilus DSM 7039 | - |
2-oxoglutarate + CO2 + NADH + H+ | - |
r | |
additional information | Thermus thermophilus | in contrast to other homoisicitrate dehydrogenases, the homoisocitrate dehydrogenase from the thermophilic bacterium Thermus thermophilus (TtHICDH) catalyzes the reactions using both homoisocitrate and isocitrate as substrates at similar efficiencies | ? | - |
? | |
additional information | Thermus thermophilus DSM 7039 | in contrast to other homoisicitrate dehydrogenases, the homoisocitrate dehydrogenase from the thermophilic bacterium Thermus thermophilus (TtHICDH) catalyzes the reactions using both homoisocitrate and isocitrate as substrates at similar efficiencies | ? | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Thermus thermophilus | Q72IW9 | - |
- |
Thermus thermophilus DSM 7039 | Q72IW9 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant enzyme from Escherichia coli by anion exchange chromatography, ammonium sufate fractionation, hydrophobic interaction chromatography, and gel filtration | Thermus thermophilus |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
homoisocitrate + NAD+ | - |
Thermus thermophilus | 2-oxoadipate + CO2 + NADH + H+ | - |
r | |
homoisocitrate + NAD+ | - |
Thermus thermophilus DSM 7039 | 2-oxoadipate + CO2 + NADH + H+ | - |
r | |
isocitrate + NAD+ | - |
Thermus thermophilus | 2-oxoglutarate + CO2 + NADH + H+ | - |
r | |
isocitrate + NAD+ | - |
Thermus thermophilus DSM 7039 | 2-oxoglutarate + CO2 + NADH + H+ | - |
r | |
additional information | in contrast to other homoisicitrate dehydrogenases, the homoisocitrate dehydrogenase from the thermophilic bacterium Thermus thermophilus (TtHICDH) catalyzes the reactions using both homoisocitrate and isocitrate as substrates at similar efficiencies | Thermus thermophilus | ? | - |
? | |
additional information | dual substrate specificity for homoisocitrate dehydrogenase | Thermus thermophilus | ? | - |
? | |
additional information | in contrast to other homoisicitrate dehydrogenases, the homoisocitrate dehydrogenase from the thermophilic bacterium Thermus thermophilus (TtHICDH) catalyzes the reactions using both homoisocitrate and isocitrate as substrates at similar efficiencies | Thermus thermophilus DSM 7039 | ? | - |
? | |
additional information | dual substrate specificity for homoisocitrate dehydrogenase | Thermus thermophilus DSM 7039 | ? | - |
? |
Subunits | Comment | Organism |
---|---|---|
tetramer | dimer of dimers | Thermus thermophilus |
Synonyms | Comment | Organism |
---|---|---|
HICDH | - |
Thermus thermophilus |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
60 | - |
assay at | Thermus thermophilus |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
33 | - |
homoisocitrate | pH 8.0, 60°C, recombinant enzyme | Thermus thermophilus | |
76 | - |
isocitrate | pH 8.0, 60°C, recombinant enzyme | Thermus thermophilus |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
8 | - |
assay at | Thermus thermophilus |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
NAD+ | - |
Thermus thermophilus | |
NADH | NADH forms specific contacts with enzyme TtHICDH. The 2'- and 3-OHs of the adenine ribose of NADH form hydrogen bonds with Asp265 conserved among HICDHs, which may serve as a determinant for the preference of HICDH family members for NAD+ to NADP+ | Thermus thermophilus |
General Information | Comment | Organism |
---|---|---|
evolution | homoisocitrate dehydrogenase, HICDH, is a member of the beta-decarboxylating dehydrogenase family | Thermus thermophilus |
metabolism | in contrast to other homoisocitrate dehydrogenases, the enzyme from the thermophilic bacterium Thermus thermophilus (TtHICDH) catalyzes the reactions using both homoisocitrate and isocitrate as substrates at similar efficiencies. The enzyme catalyzes the conversion of homoisocitrate to 2-oxoadipate using NAD+ as a coenzyme, which is the fourth reaction involved in lysine biosynthesis through the alpha-aminoadipate pathway | Thermus thermophilus |
additional information | enzyme structure modelling and molecular dynamics, the distal carboxyl group of homoiscitrate is recognized by the side chains of Ser72 and Arg85 from one subunit, and Asn173 from another subunit of a dimer unit. The enzyme recognizes the distal carboxyl group of isocitrate by Arg85 in the model. Active site structure analysis, the active site is located in the cleft between two domains. In the quaternary complex of TtHICDH, the basic residues, Arg88, Arg96, Arg118, Tyr125, and Lys171, recognize the malate moiety of HIC. Asp204 (from the otherdimer part) , Asp228, Asp232, and water molecules bind a Mg2+ ion in an octahedral coordination manner similar to those of other substrate-bound structures, e.g. PDB ID 4F7I | Thermus thermophilus |
kcat/KM Value [1/mMs-1] | kcat/KM Value Maximum [1/mMs-1] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
157.1 | - |
homoisocitrate | pH 8.0, 60°C, recombinant enzyme | Thermus thermophilus | |
262.1 | - |
isocitrate | pH 8.0, 60°C, recombinant enzyme | Thermus thermophilus |