Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
IUBMB CommentsMost mesophilic bacteria have a multimeric tryptophan synthase complex (EC 4.2.1.20) that forms L-tryptophan from L-serine and 1-C-(indol-3-yl)glycerol 3-phosphate via an indole intermediate. This intermediate, which is formed by the alpha subunits, is transferred in an internal tunnel to the beta units, which convert it to tryptophan. In thermophilic organisms the high temperature enhances diffusion and causes the loss of indole. This enzyme, which does not combine with the alpha unit to form a complex, salvages the lost indole back to L-tryptophan. It has a much lower Km for indole than the beta subunit of EC 4.2.1.20.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
L-serine + 4-hydroxyindole
4-hydroxy-L-tryptophan + H2O
-
-
-
?
L-serine + 5-hydroxyindole
5-hydroxy-L-tryptophan + H2O
-
-
-
?
L-serine + 7-hydroxyindole
7-hydroxy-L-tryptophan + H2O
-
-
-
?
L-serine + indole
L-tryptophan + H2O
L-threonine + 2-methylindole
(2S,3S)-2-methyl-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 4-fluoroindole
(2S,3S)-4-fluoro-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 4-methylindole
(2S,3S)-4-methyl-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 5-bromoindole
(2S,3S)-5-bromo-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 5-chloroindole
(2S,3S)-5-chloro-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 5-phenylindole
(2S,3S)-5-phenyl-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 6-methylindole
(2S,3S)-6-methyl-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 7-azaindole
(2S,3S)-2-amino-3-(1H-pyrrolo[2,3-b]pyridin-3-yl)butanoic acid + H2O
-
engineered mutant enzyme PfTrpB2B9
-
-
?
L-threonine + 7-chloroindole
(2S,3S)-7-chloro-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 7-fluoroindole
(2S,3S)-7-fluoro-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 7-methoxyindole
(2S,3S)-7-methoxy-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + 7-methylindole
(2S,3S)-7-methyl-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + indole
(2S,3S)-beta-methyltryptophan + H2O
additional information
?
-
L-serine + indole

L-tryptophan + H2O
-
-
-
?
L-serine + indole
L-tryptophan + H2O
L-serine is the preferred substrate
-
-
?
L-serine + indole
L-tryptophan + H2O
-
-
-
-
?
L-serine + indole
L-tryptophan + H2O
-
L-serine is the preferred substrate
-
-
?
L-serine + indole
L-tryptophan + H2O
-
Ser and IGP react with a coupling efficiency of over 99% and only trace indole is released into solution by cells
-
-
?
L-serine + indole
L-tryptophan + H2O
-
L-serine is the preferred substrate
-
-
?
L-serine + indole
L-tryptophan + H2O
-
-
-
-
?
L-serine + indole
L-tryptophan + H2O
-
-
-
?
L-serine + indole
L-tryptophan + H2O
-
the enzyme is involved in L-tryptophan biosynthesis. TrpB2 does not interact with TrpA as in the case of TrpB1. TrpB2 provides an alternate route to generate Trp from serine and free indole (indole salvage)
-
-
?
L-serine + indole
L-tryptophan + H2O
-
-
-
-
?
L-threonine + indole

(2S,3S)-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + indole
(2S,3S)-beta-methyltryptophan + H2O
-
only 17% of the indole that is released from the alpha-subunit goes on to form beta-MeTrp, demonstrating that the release of indole is decoupled from product formation. Thr binds non-covalently to the isolated beta-subunit, indicating that the beta-methyl group hinders entry into the catalytic cycle. The beta-methyl of Thr causes a steric clash that destabilizes the E(Aex1) intermediate
-
-
?
L-threonine + indole
(2S,3S)-beta-methyltryptophan + H2O
-
veryl low activity of the wild-type enzyme, higher activity with engineered mutant enzymes
-
-
?
L-threonine + indole
(2S,3S)-beta-methyltryptophan + H2O
-
-
-
-
?
additional information

?
-
enzymatic production of psilocybin formation from 4-hydroxyindole and L-serine and of 7-phosphoryloxytryptamine (isonorbaeocystin), a non-natural congener of the Psilocybe alkaloid norbaeocystin (4-phosphoryloxytryptamine), and of serotonin (5-hydroxytryptamine) by means of the same in vitro approach, overview
-
-
?
additional information
?
-
-
the rate of Thr deamination by PfTrpS is 8.5fold faster than with Ser, competitive with the rate of beta-substitution. Substrate differentiation mechanism of the enzyme, molecular dynamics simulations analysis, overview
-
-
?
additional information
?
-
-
beta-substitution occurs in vitro with a 3.4fold higher catalytic efficiency for Ser over Thr using saturating indole, despite over 82000fold preference for Ser in direct competition using IGP. When the reaction is conducted with a 1000fold molar excess of Thr over Ser, only Trp is observed, with no trace of beta-MeTrp. Atypical mechanism of specificity: Thr binds efficiently but decreases the affinity for indole and disrupts the allosteric signaling that regulates the catalytic cycle
-
-
?
additional information
?
-
-
no activity of engineered mutant enzyme with 5-chloro-, 5-bromo, and 6-hydroxyindoles combined with L-threonine
-
-
?
additional information
?
-
-
activity and isolated yields of L-beta-methyl-Trp are low compared to the wild-type reaction with l-Ser, which gives over 90% of L-Trp under the same conditions. Preperative scale synthesis (2S,3S)-L-beta-methyl tryptophan and derivatives
-
-
?
additional information
?
-
-
TrpB2 does not bind to TrpA but is catalytically highly active, has an extremely low Km value for indole
-
-
?
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
L-serine + indole
L-tryptophan + H2O
L-threonine + indole
(2S,3S)-beta-methyltryptophan + H2O
additional information
?
-
-
the rate of Thr deamination by PfTrpS is 8.5fold faster than with Ser, competitive with the rate of beta-substitution. Substrate differentiation mechanism of the enzyme, molecular dynamics simulations analysis, overview
-
-
?
L-serine + indole

L-tryptophan + H2O
-
-
-
?
L-serine + indole
L-tryptophan + H2O
-
-
-
-
?
L-serine + indole
L-tryptophan + H2O
-
Ser and IGP react with a coupling efficiency of over 99% and only trace indole is released into solution by cells
-
-
?
L-serine + indole
L-tryptophan + H2O
-
L-serine is the preferred substrate
-
-
?
L-serine + indole
L-tryptophan + H2O
-
-
-
?
L-serine + indole
L-tryptophan + H2O
-
the enzyme is involved in L-tryptophan biosynthesis. TrpB2 does not interact with TrpA as in the case of TrpB1. TrpB2 provides an alternate route to generate Trp from serine and free indole (indole salvage)
-
-
?
L-threonine + indole

(2S,3S)-beta-methyltryptophan + H2O
-
-
-
-
?
L-threonine + indole
(2S,3S)-beta-methyltryptophan + H2O
-
only 17% of the indole that is released from the alpha-subunit goes on to form beta-MeTrp, demonstrating that the release of indole is decoupled from product formation. Thr binds non-covalently to the isolated beta-subunit, indicating that the beta-methyl group hinders entry into the catalytic cycle. The beta-methyl of Thr causes a steric clash that destabilizes the E(Aex1) intermediate
-
-
?
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
additional information
additional information
-
0.00077
indole

-
Km below 0.00077 mM, at 80°C, pH not specified in the publication
0.0076
indole
pH 7.5, 85°C, recombinant TrpB2, with TrpA
0.0081
indole
-
pH 7.5, 85°C
0.0081
indole
pH 7.5, 85°C, recombinant TrpB2, without TrpA
0.035
indole
pH 7.5, 85°C, recombinant TrpB1 with TrpA
0.063
indole
pH 7.5, 85°C, recombinant TrpB1
1.4
L-serine

-
recombinant mutant L166V, pH 7.8, 37°C
1.6
L-serine
-
recombinant wild-type enzyme, pH 7.8, 37°C
50.2
L-serine
-
at 80°C, pH not specified in the publication
52
L-serine
-
recombinant mutant L166A, pH 7.8, 37°C
210
L-threonine

-
recombinant wild-type enzyme, pH 7.8, 37°C
310
L-threonine
-
recombinant mutant L166V, pH 7.8, 37°C
340
L-threonine
-
recombinant mutant L166A, pH 7.8, 37°C
additional information
additional information

Michaelis-Menten kinetics
-
additional information
additional information
steady-state Michaelis-Menten kinetics, overview
-
additional information
additional information
steady-state Michaelis-Menten kinetics, overview
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
0.00068 - 0.007
L-threonine
0.39
indole

-
pH 7.5, 85°C
0.39
indole
pH 7.5, 85°C, recombinant TrpB2, with or without TrpA
0.46
indole
-
at 80°C, pH not specified in the publication
1.04
indole
pH 7.5, 85°C, recombinant TrpB1
3.46
indole
pH 7.5, 85°C, recombinant TrpB1 with TrpA
0.082
L-serine

-
recombinant mutant L166V, pH 7.8, 37°C
0.18
L-serine
-
recombinant mutant L166A, pH 7.8, 37°C
0.35
L-serine
-
recombinant wild-type enzyme, pH 7.8, 37°C
0.44
L-serine
-
at 80°C, pH not specified in the publication
0.00068
L-threonine

-
recombinant wild-type enzyme, pH 7.8, 37°C
0.0035
L-threonine
-
recombinant mutant L166A, pH 7.8, 37°C
0.007
L-threonine
-
recombinant mutant L166V, pH 7.8, 37°C
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
0.000003 - 0.000023
L-threonine
0.0006
indole

-
KCAT_KM below 0.0006 mM, at 80°C, pH not specified in the publication
17
indole
pH 7.5, 85°C, recombinant TrpB1
48
indole
pH 7.5, 85°C, recombinant TrpB2, without TrpA
51
indole
pH 7.5, 85°C, recombinant TrpB2, with TrpA
99
indole
pH 7.5, 85°C, recombinant TrpB1 with TrpA
0.003
L-serine

-
recombinant mutant L166A, pH 7.8, 37°C
0.058
L-serine
-
recombinant mutant L166V, pH 7.8, 37°C
0.22
L-serine
-
recombinant wild-type enzyme, pH 7.8, 37°C
8700
L-serine
-
at 80°C, pH not specified in the publication
0.000003
L-threonine

-
recombinant wild-type enzyme, pH 7.8, 37°C
0.00001
L-threonine
-
recombinant mutant L166A, pH 7.8, 37°C
0.000023
L-threonine
-
recombinant mutant L166V, pH 7.8, 37°C
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
malfunction

the double-deletion mutant (DELTAtrpB1DELTAtrpB2) displays Trp auxotrophy, whereas individual single mutants (DELTAtrpB1 and DELTAtrpB2 strains) does not
malfunction
-
double-deletion mutant (DELTAtrpB1DELTAtrpB2) displays Trp auxotrophy, whereas individual single mutants (DELTAtrpB1 and DELTAtrpB2 strains) do not. To examine the capacity of TrpB1 and TrpB2 in Trp synthesis via indole salvage, DtrpEB1 and DtrpEB2 mutant strains are constructed using strain KUW1 (DELTApyrFDtrpE) as a host, eliminating the route for endogenous indole synthesis. Indole complements the Trp auxotrophies of DELTAtrpEB1 (DELTApyrFDELTAtrpEDELTAtrpB1) and DELTAtrpEB2 (DELTApyrFDELTAtrpEDELTAtrpB2) to similar levels. The results indicate that TrpB1 and TrpB2 both contribute to Trp biosynthesis in Thermococcus kodakarensis and can utilize free indole, and that indolesalvage does not necessarily rely on TrpB2 to a greater extent
metabolism

the last two steps of L-tryptophan (Trp) biosynthesis are catalyzed by Trp synthase, a heterotetramer composed of TrpA and TrpB. TrpB catalyzes the condensation of indole, synthesized by TrpA, and serine to Trp. TrpB2 catalyzes the TrpB reaction but does not interact with TrpA as in the case of TrpB1. TrpB1 and TrpB2 both contribute to Trp biosynthesis in Thermococcus kodakarensis and can utilize free indole, and indole salvage does not necessarily rely on TrpB2 to a greater extent
metabolism
-
the enzyme is involved in L-tryptophan biosynthesis
physiological function

-
TrpB2 acts as an indole rescue protein, which prevents the escape of this costly hydrophobic metabolite from the cell at the high growth temperatures of hyperthermophiles
physiological function
trpB2 contributes in Trp biosynthesis
physiological function
the enzyme is part of the tryptophan synthase complex. Indole formation is catalyzed by the alpha-subunit (TrpBalpha), L-tryptophan production is catalyzed by the beta-subunit (TrpBbeta)
physiological function
-
tryptophan synthase (TrpS) catalyzes the final steps in the biosynthesis of L-tryptophan from L-serine (Ser) and indole-3-glycerol phosphate (IGP). Native TrpS can also catalyze a productive reaction with L-threonine (Thr), leading to (2S,3S)-beta-methyltryptophan
additional information

-
leucine residue Leu166 (betaL166) is in close proximity to the beta-position of the alpha-aminoacrylate species
additional information
-
product binding site analysis
additional information
-
leucine residue Leu166 (betaL166) is in close proximity to the beta-position of the alpha-aminoacrylate species
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
dimer
-
2 * 49300, calculated from sequence
heterotetramer
Trp synthase is a heterotetramer composed of TrpA and TrpB, TrpA and TrpB1 assemble to form an alphabetabetaalpha heterotetramer
homodimer
-
2 * 46400, calculated from amino acid sequence
monomer
1 * 75500, about, TrpB monomer, sequence calculation
additional information

complex formation of TrpB1 and TrpB2 with TrpA is analyzed by gel filtration
additional information
complex formation of TrpB1 and TrpB2 with TrpA is analyzed by gel filtration
additional information
complex formation of TrpB1 and TrpB2 with TrpA is analyzed by gel filtration, TrpA and TrpB2 do not form a complex
additional information
complex formation of TrpB1 and TrpB2 with TrpA is analyzed by gel filtration, TrpA and TrpB2 do not form a complex
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
I16V/E17G/Q89L/F95L/T292S/V384A
-
site-directed mutagenesis, the mutant PfTrpB2B9 exhibits a 6000fold higher activity with L-Thr compared to wild-type
I16V/Q89L
-
site-directed mutagenesis
T292S
-
site-directed mutagenesis, the mutant exhibits a 6fold higher activity with L-Thr compared to wild-type
T292S/E17G/I68V/F274S/T321A
-
site-directed mutagenesis, the mutant exhibits a 660old higher activity with L-Thr compared to wild-type
L166A
-
site-directed mutagenesis the beta-subunit, the mutant shows altered substrate specificity compared to the wild-type enzyme
L166V
-
site-directed mutagenesis of the beta-subunit, the mutant shows altered substrate specificity compared to the wild-type enzyme, single-step enzymatic synthesis of beta-methyl-Trp derivatives, overview. Although 2-, 4-, 6- or 7-substituted indoles are accepted by StTrpS beta-L66V, along with L-Thr, 5-subsituted indoles prove to be very poor substrates for the enzyme. Variant beta-L166V can better accommodate L-Thr as a substrate
L166A
-
site-directed mutagenesis the beta-subunit, the mutant shows altered substrate specificity compared to the wild-type enzyme
-
L166V
-
site-directed mutagenesis of the beta-subunit, the mutant shows altered substrate specificity compared to the wild-type enzyme, single-step enzymatic synthesis of beta-methyl-Trp derivatives, overview. Although 2-, 4-, 6- or 7-substituted indoles are accepted by StTrpS beta-L66V, along with L-Thr, 5-subsituted indoles prove to be very poor substrates for the enzyme. Variant beta-L166V can better accommodate L-Thr as a substrate
-
additional information

biocatalytic production of psilocybin and derivatives in tryptophan synthase-enhanced reactions, in vitro reconstituted indole alkaloid synthesis pathway including enzyme PsiD, PsiK and PsiM, and ATP and S-adenosyl-L-methionine, method, overview. Assays run only with TrpB and PsiD result in identical chromatograms
additional information
-
Pyrococcus furiosus enzyme engineering by directed evolution of selected TrpB mutant PfTrpB4D11 results in an modified improved enzyme, L-threonine may substitute for L-serine in the beta-substitution reaction of the engineered subunit of tryptophan synthase yielding (2S,3S)-beta-methyltryptophan (beta-MeTrp) in a single step. The trace activity of the wild-type beta-subunit on this substrate is enhanced more than 1000fold by directed evolution. Structural and spectroscopic data indicate that this increase is correlated with stabilization of the electrophilic aminoacrylate intermediate. The engineered biocatalyst also reacts with a variety of indole analogues and thiophenol for diastereoselective C-C, C-N, and C-S bond forming reactions. The new activity circumvents the 3-enzyme pathway that produces beta-MeTrp in nature and offers a simple and expandable route to preparing derivatives of this valuable building block
additional information
-
usage of directed evolution to engineer TrpB from Pyrococcus furiosus (PfTrpB) to retain activity in the absence of its TrpA partner. Further engineering of this stand-alone enzyme achieves tha catalysis the of efficient beta-substitution of L-threonine (Thr), yielding (2S,3S)-beta-methyltryptophan (beta-MeTrp) in a single step
additional information
-
an engineered variant of tryptophan synthase from Salmonella enterica (StTrpS) can catalyse the efficient condensation of L-threonine and various indoles to generate bmTrp and derivatives in a single step. Although L-serine is the natural substrate for TrpS, targeted mutagenesis of the StTrpS active site provides a variant (bL166V) that can better accommodate L-Thr as a substrate. The condensation of L-Thr and indole proceeds with retention of configuration at both alpha- and beta-positions to give (2S,3S)-beta-methyl-Trp
additional information
-
an engineered variant of tryptophan synthase from Salmonella enterica (StTrpS) can catalyse the efficient condensation of L-threonine and various indoles to generate bmTrp and derivatives in a single step. Although L-serine is the natural substrate for TrpS, targeted mutagenesis of the StTrpS active site provides a variant (bL166V) that can better accommodate L-Thr as a substrate. The condensation of L-Thr and indole proceeds with retention of configuration at both alpha- and beta-positions to give (2S,3S)-beta-methyl-Trp
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
expressed in Escherichia coli BL21(DE3) cells
-
expression in Escherichia coli
-
gene trpB1, phylogenetic tree, expression in Escherichia coli strain BL21, transcript levels of trpB1 in the host, DELTAtrpB1 strains by quantitative RT-PCR expression analysis
gene trpB2, phylogenetic tree, expression in Escherichia coli strain BL21, transcript levels of trpB2 in the host, DELTAtrpB2 strains by quantitative RT-PCR expression analysis
gene trpS, recombinant expression in Escherichia coli
-
recombinant expression of C-terminally His-tagged wild-type and mutant enzymes in Escherichia coli strain BL21(DE3)
-
recombinant expression of N-terminally His6-tagged TrpB in Escherichia coli strain KRX
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
Hettwer, S.; Sterner, R.
A novel tryptophan synthase beta-subunit from the hyperthermophile Thermotoga maritima. Quaternary structure, steady-state kinetics, and putative physiological role
J. Biol. Chem.
277
8194-8201
2002
Thermotoga maritima
brenda
Hiyama, T.; Sato, T.; Imanaka, T.; Atomi, H.
The tryptophan synthase beta-subunit paralogs TrpB1 and TrpB2 in Thermococcus kodakarensis are both involved in tryptophan biosynthesis and indole salvage
FEBS J.
281
3113-3125
2014
Thermococcus kodakarensis (Q5JDJ1), Thermococcus kodakarensis (Q9YGB0)
brenda
Buller, A.; Van Roye, P.; Murciano-Calles, J.; Arnold, F.
tryptophan synthase uses an atypical mechanism to achieve substrate specificity
Biochemistry
55
7043-7046
2016
Pyrococcus furiosus
brenda
Francis, D.; Winn, M.; Latham, J.; Greaney, M.; Micklefield, J.
An engineered tryptophan synthase opens new enzymatic pathways to beta-methyltryptophan and derivatives
ChemBioChem
18
382-386
2017
Salmonella enterica subsp. enterica serovar Typhimurium, Salmonella enterica subsp. enterica serovar Typhimurium ATCC 37845
brenda
Blei, F.; Baldeweg, F.; Fricke, J.; Hoffmeister, D.
Biocatalytic production of psilocybin and derivatives in tryptophan synthase-enhanced reactions
Chemistry
24
10028-10031
2018
Psilocybe cubensis (A0A2U8JPY3)
brenda
Hiyama, T.; Sato, T.; Imanaka, T.; Atomi, H.
The tryptophan synthase beta-subunit paralogs TrpB1 and TrpB2 in Thermococcus kodakarensis are both involved in tryptophan biosynthesis and indole salvage
FEBS J.
281
3113-3125
2014
Thermococcus kodakarensis
brenda
Herger, M.; Van Roye, P.; Romney, D.; Brinkmann-Chen, S.; Buller, A.; Arnold, F.
Synthesis of beta-branched tryptophan analogues using an engineered subunit of tryptophan synthase
J. Am. Chem. Soc.
138
8388-8391
2016
Pyrococcus furiosus
brenda