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Literature summary for 4.2.1.20 extracted from
- The molecular pathway for the allosteric regulation of tryptophan synthase (2003), Biochim. Biophys. Acta, 1647, 157-160.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| expression of wild-type and mutants enzymes in Escherichia coli | Salmonella enterica subsp. enterica serovar Typhimurium |
Crystallization (Commentary)
| Crystallization (Comment) | Organism |
|---|---|
| crystallization of wild-type and mutant S178P in presence or absence of alpha-subunit ligands, structure comparison | Salmonella enterica subsp. enterica serovar Typhimurium |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| G181P | site-directed mutagenesis, replacement of an alphaloop6 residue, loss of the hydrogen bond between residues alphaG181 and betaS178 does not influence the intersubunit catalytic activity, but completely abolishes ligand-induced intersubunit signaling, stabilization of the inactive open conformation of the alpha-active site | Salmonella enterica subsp. enterica serovar Typhimurium |
| S178P | site-directed mutagenesis, replacement of an betahelix6 residue, loss of the hydrogen bond between residues alphaG181 and betaS178 does not influence the intersubunit catalytic activity, but completely abolishes ligand-induced intersubunit signaling, stabilization of the inactive open conformation of the alpha-active site | Salmonella enterica subsp. enterica serovar Typhimurium |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| DL-alpha-glycerol 3-phosphate | alpha-subunit ligand effects on alpha- and beta-activity wild-type and mutant G181P, on reverse alpha-activity, the rate of beta-reaction, and on the distribution of the catalytic intermediates of the beta-active site, no inhibition of the beta-reaction of mutant G181P | Salmonella enterica subsp. enterica serovar Typhimurium |  |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Salmonella enterica subsp. enterica serovar Typhimurium | - |
gene trpA encodes the alpha-subunit, gene trpB encodes the beta-subunit | - |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| L-serine + 1-C-(indol-3-yl)glycerol 3-phosphate = L-tryptophan + D-glyceraldehyde 3-phosphate + H2O | also catalyses the conversion of serine and indole into tryptophan and water, and of indoleglycerol phosphate into indole and glyceraldehyde phosphate (the latter reaction was listed formerly as EC 4.2.1.8), interaction of residues G181 and S178 are essential for the quilibrium between active closed and inactive open conformation of the alpha-active site | Salmonella enterica subsp. enterica serovar Typhimurium |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| 288 | - |
purified wild-type, beta-reaction, in presence of DL-alpha-glycerol 3-phosphate | Salmonella enterica subsp. enterica serovar Typhimurium |
| 511 | - |
purified mutant G181P, reverse alpha-reaction, in presence of DL-alpha-glycerol 3-phosphate | Salmonella enterica subsp. enterica serovar Typhimurium |
| 520 | - |
purified mutant G181P, beta-reaction, in absence or presence of DL-alpha-glycerol 3-phosphate | Salmonella enterica subsp. enterica serovar Typhimurium |
| 818 | - |
purified mutant G181P, reverse alpha-reaction, in absence of DL-alpha-glycerol 3-phosphate | Salmonella enterica subsp. enterica serovar Typhimurium |
| 1150 | - |
purified wild-type, beta-reaction, in absence of DL-alpha-glycerol 3-phosphate | Salmonella enterica subsp. enterica serovar Typhimurium |
| 1375 | - |
purified wild-type, reverse alpha-reaction, in presence of DL-alpha-glycerol 3-phosphate | Salmonella enterica subsp. enterica serovar Typhimurium |
| 1605 | - |
purified wild-type, reverse alpha-reaction, in absence of DL-alpha-glycerol 3-phosphate | Salmonella enterica subsp. enterica serovar Typhimurium |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 1-(indol-3-yl)glycerol 3-phosphate | alpha-subunit of the bienzyme complex, alpha-reaction | Salmonella enterica subsp. enterica serovar Typhimurium | D-glyceraldehyde 3-phosphate + indole | - |
? | |
| L-serine + indole | beta-subunit of the bienzyme complex, beta-reaction | Salmonella enterica subsp. enterica serovar Typhimurium | L-tryptophan + H2O | - |
? | |
| additional information | the alpha-beta subunit interaction plays a critical role both in the reciprocal activation of the individual subunits and in the allosteric regulation | Salmonella enterica subsp. enterica serovar Typhimurium | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| More | three-dimensional structure of the alphaloop6 in the closed conformation with hydrogen bond between Gly181 ans Ser178 | Salmonella enterica subsp. enterica serovar Typhimurium |
| tetramer | alpha2beta2 enzyme complex | Salmonella enterica subsp. enterica serovar Typhimurium |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| pyridoxal 5'-phosphate | dependent on | Salmonella enterica subsp. enterica serovar Typhimurium | |
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