Literature summary for 4.1.1.15 extracted from

Grassini, G.; Pennacchietti, E.; Cappadocio, F.; Occhialini, A.; De Biase, D.
Biochemical and spectroscopic properties of Brucella microti glutamate decarboxylase, a key component of the glutamate-dependent acid resistance system (2015), FEBS open bio, 5, 209-218 .

Cloned(Commentary)

Cloned (Comment)	Organism
gene gadB, recombinant expression of His-tagged enzyme in Escherichia coli strain BL21(DE3), that lacks endogenous GAD enzyme activity. The Escherichia coli strain Gad-negative phenotype might arise either from the single nucleotide polymorphisms detected in the promoter region of gadA (at position -50 relative to the transcription start site) and gadB (at position -190 relative to the transcription start site) genes or from reduced activity/expression of the transcriptional regulators necessary to trigger the expression of the GDAR system	Brucella microti

Cloned (Comment)

Organism

gene gadB, recombinant expression of His-tagged enzyme in Escherichia coli strain BL21(DE3), that lacks endogenous GAD enzyme activity. The Escherichia coli strain Gad-negative phenotype might arise either from the single nucleotide polymorphisms detected in the promoter region of gadA (at position -50 relative to the transcription start site) and gadB (at position -190 relative to the transcription start site) genes or from reduced activity/expression of the transcriptional regulators necessary to trigger the expression of the GDAR system

Brucella microti

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
additional information	-	additional information	Michaeli-Menten kinetics	Brucella microti
2.68	-	L-glutamate	pH 4.6, 25°C, recombinant enzyme	Brucella microti

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
cytoplasm	-	Brucella microti	5737	-
additional information	BmGadB does not undergo membrane recruitment at acidic pH, effect of pH on the subcellular localization of BmGadB, overview	Brucella microti	-	-

Metals/Ions

Metals/Ions	Comment	Organism	Structure
Cl-	enzyme BmGadB has the necessary structural requirements for the binding of activating chloride ions at acidic pH and for the closure of its active site at neutral pH	Brucella microti

Molecular Weight [Da]

Molecular Weight [Da]	Molecular Weight Maximum [Da]	Comment	Organism
307400	-	recombinant enzyme, gel filtration at pH 4.6	Brucella microti

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
L-glutamate	Brucella microti	-	4-aminobutanoate + CO2	-	?
L-glutamate	Brucella microti CCM 4915	-	4-aminobutanoate + CO2	-	?

Organism

Organism	UniProt	Comment	Textmining
Brucella microti	C7LHI0	-	-
Brucella microti CCM 4915	C7LHI0	-	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
L-glutamate	-	Brucella microti	4-aminobutanoate + CO2	-	?
L-glutamate	-	Brucella microti CCM 4915	4-aminobutanoate + CO2	-	?

Subunits

Subunits	Comment	Organism
homohexamer	6 x 52000, recombinant enzyme, SDS-PAGE	Brucella microti
More	at acidic pH, when the enzyme is maximally active, BmGadB is a hexamer	Brucella microti

Synonyms

Synonyms	Comment	Organism
BmGadB	-	Brucella microti
BMI_II334	-	Brucella microti
GAD	-	Brucella microti
GadB	-	Brucella microti

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
25	-	assay at	Brucella microti

Turnover Number [1/s]

Turnover Number Minimum [1/s]	Turnover Number Maximum [1/s]	Substrate	Comment	Organism	Structure
17.88	-	L-glutamate	pH 4.6, 25°C, recombinant enzyme	Brucella microti

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
4.6	-	assay at	Brucella microti

pH Range

pH Minimum	pH Maximum	Comment	Organism
additional information	-	sigmoidal pH-dependence curve. Enzyme BmGadB displays its maximal activity at low pH, but only up to pH 4.5. At pH 5.0 the enzyme exhibits 50% of the activity measured at pH 3.8-4.5 and activity becomes undetectable at a pH higher than pH 5.6. In the range of pH 3.8-5.3 BmGadB is 1.5-3 times more active when chloride ions are present	Brucella microti

Cofactor

Cofactor	Comment	Organism	Structure
pyridoxal 5'-phosphate	-	Brucella microti

General Information

General Information	Comment	Organism
evolution	Brucella microti belongs to a group of atypical brucellae that possess functional gadB and gadC genes, unlike the most well-known classical Brucella species, which include important human pathogens	Brucella microti
additional information	enzyme BmGadB has the necessary structural requirements for the binding of activating chloride ions at acidic pH and for the closure of its active site at neutral pH. BmGadB does not undergo membrane recruitment at acidic pH. For this enzyme to be functional in the glutamate-dependent acid resistance system (GDAR), some structural features must be preserved. The active form of BmGadB has internal aldimine protonated on the imine nitrogen, a pre-requisite for being catalytically competent	Brucella microti
physiological function	glutamate decarboxylase is a key component of the glutamate-dependent acid resistance system in Brucella microti. The glutamate-dependent acid resistance system (GDAR) is the most efficient molecular system in conferring protection from acid stress, structural overview	Brucella microti

kcat/KM [mM/s]

kcat/KM Value [1/mMs^-1]	kcat/KM Value Maximum [1/mMs^-1]	Substrate	Comment	Organism	Structure
6.66	-	L-glutamate	pH 4.6, 25°C, recombinant enzyme	Brucella microti