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Literature summary for 2.6.1.96 extracted from

  • Clark, S.M.; Di Leo, R.; Dhanoa, P.K.; Van Cauwenberghe, O.R.; Mullen, R.T.; Shelp, B.J.
    Biochemical characterization, mitochondrial localization, expression, and potential functions for an Arabidopsis gamma-aminobutyrate transaminase that utilizes both pyruvate and glyoxylate (2009), J. Exp. Bot., 60, 1743-1757.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

Cloned (Comment) Organism
gene pop2, expression of N-termminally His6-tagged GABA-T POP2 in Escherichia coli strain BL-21(DE3) Rosetta (pLysS) Arabidopsis thaliana
transient expression of GABA-T in Nicotiana tabacum BY-2 cells. C-terminal myc-tagged GABA-T co-localizes with coexpressed mitochondrial betaATPase-CAT in BY-2 cells Arabidopsis thaliana

Protein Variants

Protein Variants Comment Organism
additional information a truncated AtGABA-T cDNA lacking the putative N-terminal targeting pre-sequence is co-expressed with the molecular chaperones GroES/EL in Escherichia coli, substrate specificity and kinetic studies reveal that the recombinant enzyme utilizes only GABA as the amino donor in the production of succinate semialdehyde Arabidopsis thaliana

Inhibitors

Inhibitors Comment Organism Structure
beta-Alanine
-
Arabidopsis thaliana
glycine
-
Arabidopsis thaliana
ornithine
-
Arabidopsis thaliana
vigabatrin
-
Arabidopsis thaliana

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information Michaelis-Menten kinetic analysis, overview Arabidopsis thaliana
0.014
-
succinate semialdehyde reverse reaction with L-alanine, pH 9.0, 30°C Arabidopsis thaliana
0.11
-
glyoxylate forward reaction with 4-aminobutanoate, pH 9.0, 30°C Arabidopsis thaliana
0.14
-
pyruvate forward reaction with 4-aminobutanoate, pH 9.0, 30°C Arabidopsis thaliana
0.14
-
glyoxylate reverse reaction with L-alanine, pH 9.0, 30°C Arabidopsis thaliana
0.18
-
4-aminobutanoate forward reaction with glyoxylate, pH 9.0, 30°C Arabidopsis thaliana
0.34
-
4-aminobutanoate forward reaction with pyruvate, pH 9.0, 30°C Arabidopsis thaliana
2.2
-
L-alanine reverse reaction with glyoxylate, pH 9.0, 30°C Arabidopsis thaliana
2.4
-
L-alanine reverse reaction with succinate semialdehyde, pH 9.0, 30°C Arabidopsis thaliana

Localization

Localization Comment Organism GeneOntology No. Textmining
mitochondrion
-
Arabidopsis thaliana 5739
-
additional information subcellular localization analysis, overview Arabidopsis thaliana
-
-

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
53400
-
x * 57500, recombinant full-length GABA-T, SDS-PAGE, x * 53400, recombinant truncated GABA-T, SDS-PAGE Arabidopsis thaliana
57500
-
x * 57500, recombinant full-length GABA-T, SDS-PAGE, x * 53400, recombinant truncated GABA-T, SDS-PAGE Arabidopsis thaliana

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
4-aminobutanoate + glyoxylate Arabidopsis thaliana
-
succinate semialdehyde + glycine
-
ir
4-aminobutanoate + glyoxylate Arabidopsis thaliana Wassilewskija
-
succinate semialdehyde + glycine
-
ir
4-aminobutanoate + glyoxylate Arabidopsis thaliana Col-0
-
succinate semialdehyde + glycine
-
ir
4-aminobutanoate + pyruvate Arabidopsis thaliana
-
succinate semialdehyde + L-alanine
-
r

Organism

Organism UniProt Comment Textmining
Arabidopsis thaliana Q94CE5 gene GABAT1-1 (Salk_007661) and knockout line of ecotype Columbia
-
Arabidopsis thaliana Q94CE5 POP2; gene pop2, POP2-3 (CS6387) and knockout line of ecotypes Wassilewskija
-
Arabidopsis thaliana Col-0 Q94CE5 gene GABAT1-1 (Salk_007661) and knockout line of ecotype Columbia
-
Arabidopsis thaliana Wassilewskija Q94CE5 POP2; gene pop2, POP2-3 (CS6387) and knockout line of ecotypes Wassilewskija
-

Purification (Commentary)

Purification (Comment) Organism
recombinant His6-tagged GABA-T POP2 from Escherichia coli strain BL-21(DE3) Rosetta (pLysS) by nickel affinity chromatography Arabidopsis thaliana

Source Tissue

Source Tissue Comment Organism Textmining
seedling
-
Arabidopsis thaliana
-

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
additional information
-
native GABA-T activity in cell-free extracts of Arabidopsis thaliana ecotype Columbia and corresponding knockout mutant, overview Arabidopsis thaliana
additional information
-
native GABA-T activity in cell-free extracts of Arabidopsis thaliana ecotype Wassilewskija and corresponding knockout mutant, overview Arabidopsis thaliana
0.0004
-
crude enzyme extract, substrate pyruvate, pH 9.0, 30°C Arabidopsis thaliana
3.53
-
purified recombinant full-length enzyme, substrate pyruvate, pH 9.0, 30°C Arabidopsis thaliana
7.54
-
purified recombinant truncated enzyme, substrate pyruvate, pH 9.0, 30°C Arabidopsis thaliana

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
4-aminobutanoate + glyoxylate
-
Arabidopsis thaliana succinate semialdehyde + glycine
-
ir
4-aminobutanoate + glyoxylate the glyoxylate-dependent reaction is not reversible, although glyoxylate can also be used in conjunction with alanine as a substrate in the reverse reaction Arabidopsis thaliana succinate semialdehyde + glycine
-
ir
4-aminobutanoate + glyoxylate
-
Arabidopsis thaliana Wassilewskija succinate semialdehyde + glycine
-
ir
4-aminobutanoate + glyoxylate
-
Arabidopsis thaliana Col-0 succinate semialdehyde + glycine
-
ir
4-aminobutanoate + pyruvate
-
Arabidopsis thaliana succinate semialdehyde + L-alanine
-
r
4-aminobutanoate + pyruvate the pyruvate-dependent GABA-T reaction is reversible Arabidopsis thaliana succinate semialdehyde + L-alanine
-
r
glyoxylate + L-alanine
-
Arabidopsis thaliana ?
-
?
additional information GABA-T catalyses the breakdown of GABA to succinic semialdehyde. The enzyme shows both pyruvate- and glyoxylate-dependent activities, but no activity with 2-oxoglutarate. The substrate specificity at pH 9 reveals that the enzyme utilizes glyoxylate, as well as pyruvate, as amino acceptors in the forward reaction, and GABA, but not beta-alanine, ornithine, acetylornithine, serine, glycine, asparagine, glutamine, glutamate, valine, leucine, isoleucine, methionine, phenylalanine, histidine, lysine, arginine, aspartate, threonine, tyrosine, tryptophan, proline, or cysteine as amino donors Arabidopsis thaliana ?
-
?
additional information GABA-T catalyses the breakdown of GABA to succinic semialdehyde. The enzyme shows both pyruvate- and glyoxylate-dependent activities, but no activity with 2-oxoglutarate. The substrate specificity at pH 9 reveals that the enzyme utilizes glyoxylate, as well as pyruvate, as amino acceptors in the forward reaction, and GABA, but not beta-alanine, ornithine, acetylornithine, serine, glycine, asparagine, glutamine, glutamate, valine, leucine, isoleucine, methionine, phenylalanine, histidine, lysine, arginine, aspartate, threonine, tyrosine, tryptophan, proline, or cysteine as amino donors Arabidopsis thaliana Wassilewskija ?
-
?
additional information GABA-T catalyses the breakdown of GABA to succinic semialdehyde. The enzyme shows both pyruvate- and glyoxylate-dependent activities, but no activity with 2-oxoglutarate. The substrate specificity at pH 9 reveals that the enzyme utilizes glyoxylate, as well as pyruvate, as amino acceptors in the forward reaction, and GABA, but not beta-alanine, ornithine, acetylornithine, serine, glycine, asparagine, glutamine, glutamate, valine, leucine, isoleucine, methionine, phenylalanine, histidine, lysine, arginine, aspartate, threonine, tyrosine, tryptophan, proline, or cysteine as amino donors Arabidopsis thaliana Col-0 ?
-
?

Subunits

Subunits Comment Organism
? x * 57500, recombinant full-length GABA-T, SDS-PAGE, x * 53400, recombinant truncated GABA-T, SDS-PAGE Arabidopsis thaliana

Synonyms

Synonyms Comment Organism
GABA-T
-
Arabidopsis thaliana
gamma-aminobutyrate transaminase
-
Arabidopsis thaliana
Pop2
-
Arabidopsis thaliana

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
30
-
assay at Arabidopsis thaliana

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
6.9
-
4-aminobutanoate forward reaction with glyoxylate, pH 9.0, 30°C Arabidopsis thaliana
9.7
-
glyoxylate forward reaction with 4-aminobutanoate, pH 9.0, 30°C Arabidopsis thaliana
10.6
-
pyruvate forward reaction with 4-aminobutanoate, pH 9.0, 30°C Arabidopsis thaliana
10.6
-
4-aminobutanoate forward reaction with pyruvate, pH 9.0, 30°C Arabidopsis thaliana
10.8
-
succinate semialdehyde reverse reaction with L-alanine, pH 9.0, 30°C Arabidopsis thaliana
12.1
-
glyoxylate reverse reaction with L-alanine, pH 9.0, 30°C Arabidopsis thaliana
14.1
-
L-alanine reverse reaction with glyoxylate, pH 9.0, 30°C Arabidopsis thaliana
15.4
-
L-alanine reverse reaction with succinate semialdehyde, pH 9.0, 30°C Arabidopsis thaliana

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
9
-
pyruvate-dependent forward reaction Arabidopsis thaliana

pH Range

pH Minimum pH Maximum Comment Organism
8 10.5 pyruvate-dependent forward reaction Arabidopsis thaliana

Cofactor

Cofactor Comment Organism Structure
pyridoxal 5'-phosphate
-
Arabidopsis thaliana

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.46
-
ornithine forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C Arabidopsis thaliana
0.55
-
beta-Alanine forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C Arabidopsis thaliana
0.62
-
vigabatrin forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C Arabidopsis thaliana
3.7
-
glycine forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C Arabidopsis thaliana

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
6.4
-
L-alanine reverse reaction with succinate semialdehyde, pH 9.0, 30°C Arabidopsis thaliana
6.5
-
L-alanine reverse reaction with glyoxylate, pH 9.0, 30°C Arabidopsis thaliana
31
-
4-aminobutanoate forward reaction with pyruvate, pH 9.0, 30°C Arabidopsis thaliana
39
-
4-aminobutanoate forward reaction with glyoxylate, pH 9.0, 30°C Arabidopsis thaliana
76
-
pyruvate forward reaction with 4-aminobutanoate, pH 9.0, 30°C Arabidopsis thaliana
86
-
glyoxylate reverse reaction with L-alanine, pH 9.0, 30°C Arabidopsis thaliana
88
-
glyoxylate forward reaction with 4-aminobutanoate, pH 9.0, 30°C Arabidopsis thaliana
770
-
succinate semialdehyde reverse reaction with L-alanine, pH 9.0, 30°C Arabidopsis thaliana