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I397V/I406L/S411A
mutation to residues found in isoforms Gdh1 and Gdh2, increase in thermal stability
I406L/S411A
mutation to residues found in isoforms Gdh1 and Gdh2, increase in thermal stability
S411A
mutation to residue found in isoforms Gdh1 and Gdh2, increase in thermal stability
HH454Y
mutation causes the hyperinsulinism/hyperammonemia syndrome (HHS) where insulin is hypersecreted upon consumption of protein due to loss of GLZD1 function. Mutation lies in the GTP binding pocket
A456G
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mutant of isoenzyme hGDH2 shows no change in heat inactivation process compared to wild-type enzyme
C119A
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reduction in the ADP-ribosylation
C119G
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reduction in the ADP-ribosylation
C119Y
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reduction in the ADP-ribosylation
C274A
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reduction in the ADP-ribosylation
C274G
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reduction in the ADP-ribosylation
C274Y
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reduction in the ADP-ribosylation
C323G
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decreased turnover rate of both isoenzymes as compared to wild-type
C323L
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decreased turnover rate of both isoenzymes as compared to wild-type
C323M
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decreased turnover rate of both isoenzymes as compared to wild-type
C323R
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decreased turnover rate of both isoenzymes as compared to wild-type
C323Y
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decreased turnover rate of both isoenzymes as compared to wild-type
C59A
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reduction in the ADP-ribosylation
C59G
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reduction in the ADP-ribosylation
D185A
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site-directed mutagenesis, the mutant shows no activation by leucine in contrast to the wild-type enzyme
E279L
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14.1fold increase in Km-value for NAD+
E279M
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14.1fold increase in Km-value for NAD+
E279R
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10.7fold increase in Km-value for NAD+
E279Y
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11.8fold increase in Km-value for NAD+
G446C
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a one-month-old boy with a rare form of congenital hyperinsulinism characterised by hypoglycaemia and hyperammonaemia is described. The patient is heterozygous for a novel de novo mutation in the GLUD1 gene in exon 11 of chromosome 10, which encodes glutamate dehydrogenase (GDH). This point mutation alters the corresponding guanine-guanine-thymine (GGT) codon to thymine-guaninethymine (TGT), changing the glycine at position 446 to cysteine (Gly446Cys), which is located on the allosteric domain of the enzyme. The result confirmed the diagnosis of hyperinsulinism and hyperammonaemia syndrome. The patient is treated with diazoxide (12 mg/kg/day) and the glucose infusion is gradually decreased over four days. Blood glucose is maintained around 4 mmol/l. However, the infants ammonia level remain above 120 mmol/l
G446D
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kinetic parameters are almost identical to that of the wild-type enzyme. Subunit composition and polymerisation process are not affected by matagenesis
H470R
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mutant of isoenzyme hGDH2 shows no change in heat inactivation process compared to wild-type enzyme
K333L
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kinetic parameters are almost identical to that of the wild-type enzyme. Subunit composition and polymerisation process are not affected by matagenesis
K337L
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kinetic parameters are almost identical to that of the wild-type enzyme. Subunit composition and polymerisation process are not affected by matagenesis
K344L
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kinetic parameters are almost identical to that of the wild-type enzyme. Subunit composition and polymerisation process are not affected by matagenesis
K346L
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kinetic parameters are almost identical to that of the wild-type enzyme. Subunit composition and polymerisation process are not affected by matagenesis
K450E
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mutation in the pivot helix, mutant shows diminished basal activity and a strongly decreased maximal activity, no activation by L-leucine, ADP restores the decreased activity of K450E but this occurs at substantially higher concentrations compared to wild-type, mutant shows an increased resistance to GTP inhibition, mutation makes the enzyme extremely heat-labile compared to wild-type. IC50 (GTP): 180
K450G
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mutant enzyme is unable to bind GTP, no difference in sensitivity to aluminum binding between wild-type and mutant enzyme
L415M
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mutant of isoenzyme hGDH2 shows no change in heat inactivation process compared to wild-type enzyme
L415M/S443R/A456G
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triple mutant hGDH2(hGDH1390-465)hGDH2 (amino acid segment 390-465 of hGDH2 replaced by the corresponding hGDH1 segment)
M370L
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mutation does not abolish basal activity and does not abrogate the activation of the enzyme by L-Leu
M415L
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mutation does not abolish basal activity and does not abrogate the activation of the enzyme by L-Leu
M415L/R443S/G456A
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triple mutant hGDH1(hGDH2390-465)hGDH1 (amino acid segment 390-465 of hGDH1 replaced by the corresponding hGDH2 segment)
M415L/R443S/G456A/R470H
site-directed mutagenesis
N498S
mutation does not render the enzyme resistant to GTP inhibition
R151M
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site-directed mutagenesis, the mutant shows reduced activation by leucine compared to the wild-type enzyme
R443S/G456A
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resistant to GTP inhibition
R463A
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stimulatory effect of ADP is eliminated
S331T
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mutation does not abolish basal activity and does not abrogate the activation of the enzyme by L-Leu
S443R
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mutant of isoenzyme hGDH2 shows a dramatic increase in thermal stability from 45 min at 45°C for the wild-type enzyme to 300 min for the mutant enzyme. KM-values and turnover-numbers are nearly identical to wild-type enzyme
S445A
site-directed mutagenesis, the specific antibody, generated from 12-amino acid hGDH2-specific peptide PTAEFQDSISGA, corresponding to residues 436-447 of the mature human protein, shows reduced reactivity with the enzyme mutant
Y187E
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KM-values for NADH and 2-oxoglutareta are similar to wild-type values, about 4fold decrease of Vmax
Y187M
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KM-values for NADH and 2-oxoglutareta are similar to wild-type values, about 4fold decrease of Vmax, no significant actication by ADP
Y187S
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KM-values for NADH and 2-oxoglutareta are similar to wild-type values, about 4fold decrease of Vmax, no significant actication by ADP
Y197R
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KM-values for NADH and 2-oxoglutareta are similar to wild-type values, about 4fold decrease of Vmax, no significant actication by ADP
up
show higher activities in cells grown on the peptides-plus-S(0) medium than in cells using maltose as the sole carbon source
A72D
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site-directed mutagenesis, the mutant shows no activation by leucine in contrast to the wild-type enzyme
D166A
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site-directed mutagenesis, the mutant shows reduced activation by leucine compared to the wild-type enzyme
I71T
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site-directed mutagenesis, the mutant shows reduced activation by leucine compared to the wild-type enzyme
R134A
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site-directed mutagenesis, the mutant shows no activation by leucine in contrast to the wild-type enzyme
Y38S
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site-directed mutagenesis, the mutant shows reduced activation by leucine compared to the wild-type enzyme
D172Y
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ratio of turnover number to Km-value for NAD+ is 1.22fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 1.2fold lower than the wild-type value, isoenzyme hGDH1
D172Y
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ratio of turnover number to Km-value for NAD+ is 1.2fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 1.1fold lower than the wild-type value, reduced sensitivity to ADP activation, isoenzyme hGDH2
E279G
-
9.8fold increase in Km-value for NAD+
E279G
-
mutant enzyme is unable to bind NAD+, no difference in sensitivity to aluminum binding between wild-type and mutant enzyme
G456A
mutant enzyme is resistant to GTP
G456A
mutation renders the enzyme markedly resistant to GTP inhibition, mutation abolishes the cooperative behavior of the enzyme
G456A
naturally occuring mutation, an evolutionary amino acid substitution compared to hGDH1 which confers GTP resistance, residue 456 from the pivot helix has a key role in the transition between closed and open conformations, a process which includes movements of the pivot helix and the NAD+-binding domain, leading to the opening of the active site cleft. Local flexibility is affected by an intersubunit hydrophobic interaction at the base of the antenna between residues Phe387 and Leu401. In GDH1, flexibility is also affected by the presence of the small and flexible Gly456 residue which packs against the Phe and Leu. Replacement of Gly by the bulkier and less flexible Ala456 in hGDH2 is expected to reduce local flexibility, and thus to affect the opening and closing of the active site cleft
G456A
site-directed mutagenesis, residue 456 from the pivot helix has a key role in the transition between closed and open conformations, a process which includes movements of the pivot helix and the NAD+-binding domain, leading to the opening of the active site cleft. Local flexibility is affected by an intersubunit hydrophobic interaction at the base of the antenna between residues Phe387 and Leu401. In GDH1, flexibility is also affected by the presence of the small and flexible Gly456 residue which packs against the Phe and Leu. Replacement of Gly by the bulkier and less flexible Ala456 as in hGDH2 is expected to reduce local flexibility, and thus to affect the opening and closing of the active site cleft
G96Y
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ratio of turnover number to Km-value for NAD+ is 1.4fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 13.5fold lower than the wild-type value, isoenzyme hGDH1
G96Y
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ratio of turnover number to Km-value for NAD+ is 1.4fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 14.3fold lower than the wild-type value, isoenzyme hGDH2
H454Y
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lower basal activity but comparable maximal activity as wild-type
H454Y
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mutation results in depolymerization of hexameric enzyme into active trimers. Mutation has no effect on expression or stability of the protein. The Km-value for NADH is 1.5fold greater than the wild-type value and the KM-value for 2-oxoglutarate is 2.5fold greater than the wild-type value. Vmax values are similar for wild-type and mutant enzyme
H454Y
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mutation in the pivot helix, mutant shows diminished basal activity and a strongly decreased maximal activity, almost no activation by L-leucine, mutant H454Y requires higher concentrations of ADP for its activation than the wild-type, mutant shows an increased resistance to GTP inhibition, mutation makes the enzyme extremely heat-labile compared to wild-type. IC50 (GTP): 2.92
K118Y
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ratio of turnover number to Km-value for NAD+ is 1.8fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 9.9fold lower than the wild-type value, isoenzyme hGDH1
K118Y
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ratio of turnover number to Km-value for NAD+ is 2fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 8.1fold lower than the wild-type value, isoenzyme hGDH2
K130Y
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ratio of turnover number to Km-value for NAD+ is 26.5fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 35fold lower than the wild-type value, isoenzyme hGDH2
K130Y
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ratio of turnover number to Km-value for NAD+ is 41.6fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 47.3fold lower than the wild-type value, isoenzyme hGDH1
K94Y
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ratio of turnover number to Km-value for NAD+ is 5.6fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 25.5fold lower than the wild-type value, isoenzyme hGDH2
K94Y
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ratio of turnover number to Km-value for NAD+ is 6.6fold lower than the wild-type value. Ratio of turnover number to Km-value for glutamate is 37.8fold lower than the wild-type value, isoenzyme hGDH1
Q441R
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mutation in the small helix of the antenna, basal activity increased by 2fold compared to wild-type, potentiated activation by L-leucine, Q411R substitution has little effect on the allosteric regulation of the mutant by ADP and GTP compared to wild-type, mutation makes the enzyme more resistant to thermal inactivation compared to wild-type. IC50 (GTP): 0.227
Q441R
site-directed mutagenesis, the specific antibody, generated from 12-amino acid hGDH2-specific peptide PTAEFQDSISGA, corresponding to residues 436-447 of the mature human protein, shows reduced reactivity with the enzyme mutant
R443S
mutation abolishes basal activity and renders the enzyme dependent on ADP for function
R443S
-
mutation abolishes basal activity and totally abrogates the activation of the enzyme by L-Leu, 1-10 mM, in absence of other effectors. When ADP, 0.025-0.1 mM, is present, L-Leu (0.3-6.0 mM) activates the mutant enzyme up to 2000%. The mutant enzyme is much less sensitive to ADP than the wild-type enzyme, however at 1 mM ADP the Vmax is comparable with that of wild-type enzyme GLUD1 GDH. KM-value for 2-oxoglutarate is similar to wild-type value
R443S
naturally occuring mutation, an evolutionary amino acid substitution which is associated with lower basal activity, though still permitting activation by ADP. Replacement of the GDH1 residue Arg443 by Ser in GDH2 was a key event early in the evolution of the GLUD2 gene in humans and great apes, which has been related with a lower basal activity and heat sensitivity. Arg443 is involved in the stabilization of open and closed conformations of GDH1. GDH1 structures reveal that the transition from open to closed conformations is associated with partial unfolding of the C-terminus of the descending helix, immediately after residue Arg443, thereby reducing the length of the helix by almost a half turn. Arg443 forms conserved intersubunit hydrogen bonds with backbone and/or side chains of Asp408 and Ser409 residues from the ascending helix of a neighbouring chain and a conserved stacking interaction with Tyr405. Through these interactions, Arg443 establishes crucial intersubunit connections that mutually stabilize the ascending and descending helices. In contrast, substitution of Arg443 by Ser in hGDH2 leads to a loss of the above interactions, and a loose packing in the antenna region. This results in a higher flexibility in the area and in a lower stability of the enzyme, which subsequently may contribute to a lower enzymatic basal activity and an increased heat sensitivity
R443S
site-directed mutagenesis, replacement of the GDH1 residue Arg443 by Ser in GDH2 was a key event early in the evolution of the GLUD2 gene in humans and great apes, which has been related with a lower basal activity and heat sensitivity. Arg443 is involved in the stabilization of open and closed conformations of GDH1. GDH1 structures reveal that the transition from open to closed conformations is associated with partial unfolding of the C-terminus of the descending helix, immediately after residue Arg443, thereby reducing the length of the helix by almost a half turn. Arg443 forms conserved intersubunit hydrogen bonds with backbone and/or side chains of Asp408 and Ser409 residues from the ascending helix of a neighbouring chain and a conserved stacking interaction with Tyr405. Through these interactions, Arg443 establishes crucial intersubunit connections that mutually stabilize the ascending and descending helices. In contrast, substitution of Arg443 by Ser in hGDH2 leads to a loss of the above interactions, and a loose packing in the antenna region. This results in a higher flexibility in the area and in a lower stability of the enzyme, as we observed in earlier studies, which subsequently may contribute to a lower enzymatic basal activity and an increased heat sensitivity
R470H
mutation does not render the enzyme resistant to GTP inhibition
R470H
naturally occuring mutation, an evolutionary amino acid substitution
S445L
-
kinetic parameters are almost identical to that of the wild-type enzyme. Subunit composition and polymerisation process are not affected by matagenesis
S445L
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mutation in the small helix of the antenna, basal activity increased by 2fold compared to wild-type, potentiated activation by L-leucine, S445L mutant retains the regulatory properties of the wild-type concerning its activation by ADP and inhibition by GTP, mutation makes the enzyme more resistant to thermal inactivation compared to wild-type. IC50 (GTP): 0.317
S448P
-
unstable in Tris-buffer especially in the absence of allosteric activators, basal and maximal specific activity is lower than that from wild-type
S448P
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mutation located in the junction of the antenna with the pivot helix, mutant shows reduced basal activity without significantly altering the allosteric regulation by GTP or ADP, mutant is slightly induced by L-leucine. IC50 (GTP): 0.186
Y187G
-
KM-values for NADH and 2-oxoglutareta are similar to wild-type values, about 4fold decrease of Vmax, no significant actication by ADP
Y187G
-
mutant enzyme is unable to bind ADP, no difference in sensitivity to aluminum binding between wild-type and mutant enzyme
additional information
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the catalytic properties of the chimeric enzymes GDH1(GDH2390-448)GDH1 and GDH2(GDH1390-448)GDH2 are not altered compared to the wild type enzyme and show almost identical sensitivity to palmitoyl-CoA inhibitory aspects of the original wild type isozymes
additional information
neither FLAG nor (His)6 tags disturb the mitochondrial localization of GDH. The addition of the small tags to the N-terminus of the mature mitochondrial enzyme does not change the ADP activation or GTP inhibition pattern of the proteins
additional information
neither FLAG nor (His)6 tags disturb the mitochondrial localization of GDH. The addition of the small tags to the N-terminus of the mature mitochondrial enzyme does not change the ADP activation or GTP inhibition pattern of the proteins
additional information
-
neither FLAG nor (His)6 tags disturb the mitochondrial localization of GDH. The addition of the small tags to the N-terminus of the mature mitochondrial enzyme does not change the ADP activation or GTP inhibition pattern of the proteins
additional information
neither FLAG nor (His)6 tags disturb the mitochondrial localization of GDH. The addition of the small tags to the N-terminus of the mature mitochondrial enzyme does not change the ADP activation or GTP inhibition pattern of the proteins. The addition of FLAG tag to the C-terminus of the mouse GDH left the recombinant protein fivefold less sensitive to ADP activation
additional information
-
neither FLAG nor (His)6 tags disturb the mitochondrial localization of GDH. The addition of the small tags to the N-terminus of the mature mitochondrial enzyme does not change the ADP activation or GTP inhibition pattern of the proteins. The addition of FLAG tag to the C-terminus of the mouse GDH left the recombinant protein fivefold less sensitive to ADP activation
additional information
growth analysis of the aprth knockout strain (Tt27DELTAAPRTh) and aprth-overexpressing strain (Tt27NStHisAPRTh) of Thermus thermophilus in minimal medium. The Tt27DELTAAPRTh strain exhibits delayed growth and requires approximately 36 h to reach the early stationary phase, whereas the wild-type strain reaches this phase after 21 h of cultivation. The overexpressing Tt27NStHisAPRTh strain exhibits better growth than even the wild-type strain
additional information
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growth analysis of the aprth knockout strain (Tt27DELTAAPRTh) and aprth-overexpressing strain (Tt27NStHisAPRTh) of Thermus thermophilus in minimal medium. The Tt27DELTAAPRTh strain exhibits delayed growth and requires approximately 36 h to reach the early stationary phase, whereas the wild-type strain reaches this phase after 21 h of cultivation. The overexpressing Tt27NStHisAPRTh strain exhibits better growth than even the wild-type strain