PDBsum entry 2j9z

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protein ligands metals Protein-protein interface(s) links
Lyase PDB id
Protein chains
252 a.a. *
393 a.a. *
Waters ×574
* Residue conservation analysis
PDB id:
Name: Lyase
Title: Tryptophan synthase t110 mutant complex
Structure: Tryptophan synthase alpha chain. Chain: a. Engineered: yes. Tryptophan synthase beta chain. Chain: b. Engineered: yes. Mutation: yes
Source: Salmonella typhimurium. Organism_taxid: 602. Expressed in: escherichia coli. Expression_system_taxid: 562.
1.80Å     R-factor:   0.187     R-free:   0.218
Authors: L.Blumenstein,T.Domratcheva,D.Niks,H.Ngo,R.Seidel,M.F.Dunn, I.Schlichting
Key ref: L.Blumenstein et al. (2007). BetaQ114N and betaT110V mutations reveal a critically important role of the substrate alpha-carboxylate site in the reaction specificity of tryptophan synthase. Biochemistry, 46, 14100-14116. PubMed id: 18004874 DOI: 10.1021/bi7008568
16-Nov-06     Release date:   04-Dec-07    
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Protein chain
Pfam   ArchSchema ?
P00929  (TRPA_SALTY) -  Tryptophan synthase alpha chain
268 a.a.
252 a.a.*
Protein chain
Pfam   ArchSchema ?
P0A2K1  (TRPB_SALTY) -  Tryptophan synthase beta chain
397 a.a.
393 a.a.*
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 3 residue positions (black crosses)

 Enzyme reactions 
   Enzyme class: Chains A, B: E.C.  - Tryptophan synthase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]

Tryptophan Biosynthesis
      Reaction: L-serine + 1-C-(indol-3-yl)glycerol 3-phosphate = L-tryptophan + D-glyceraldehyde 3-phosphate + H2O
+ 1-C-(indol-3-yl)glycerol 3-phosphate
= L-tryptophan
+ D-glyceraldehyde 3-phosphate
+ H(2)O
      Cofactor: Pyridoxal 5'-phosphate
Pyridoxal 5'-phosphate
Bound ligand (Het Group name = PLP) matches with 93.00% similarity
Molecule diagrams generated from .mol files obtained from the KEGG ftp site
 Gene Ontology (GO) functional annotation 
  GO annot!
  Biological process     metabolic process   5 terms 
  Biochemical function     catalytic activity     4 terms  


DOI no: 10.1021/bi7008568 Biochemistry 46:14100-14116 (2007)
PubMed id: 18004874  
BetaQ114N and betaT110V mutations reveal a critically important role of the substrate alpha-carboxylate site in the reaction specificity of tryptophan synthase.
L.Blumenstein, T.Domratcheva, D.Niks, H.Ngo, R.Seidel, M.F.Dunn, I.Schlichting.
In the PLP-requiring alpha2beta2 tryptophan synthase complex, recognition of the substrate l-Ser at the beta-site includes a loop structure (residues beta110-115) extensively H-bonded to the substrate alpha-carboxylate. To investigate the relationship of this subsite to catalytic function and to the regulation of substrate channeling, two loop mutants were constructed: betaThr110 --> Val, and betaGln114 --> Asn. The betaT110V mutation greatly impairs both catalytic activity in the beta-reaction, and allosteric communication between the alpha- and beta-sites. The crystal structure of the betaT110V mutant shows that the modified l-Ser carboxylate subsite has altered protein interactions that impair beta-site catalysis and the communication of allosteric signals between the alpha- and beta-sites. Purified betaQ114N consists of two species of mutant protein, one with a reddish color (lambdamax = 506 nm). The reddish species is unable to react with l-Ser. The second betaQ114N species displays significant catalytic activities; however, intermediates obtained on reaction with substrate l-Ser and substrate analogues exhibit perturbed UV/vis absorption spectra. Incubation with l-Ser results in the formation of an inactive species during the first 15 min with lambdamax approximately 320 nm, followed by a slower conversion over 24 h to the species with lambdamax = 506 nm. The 320 and 506 nm species originate from conversion of the alpha-aminoacrylate external aldimine to the internal aldimine and alpha-aminoacrylate, followed by the nucleophilic attack of alpha-aminoacrylate on C-4' of the internal aldimine to give a covalent adduct with PLP. Subsequent treatment with sodium hydroxide releases a modified coenzyme consisting of a vinylglyoxylic acid moiety linked through C-4' to the 4-position of the pyridine ring. We conclude that the shortening of the side chain accompanying the replacement of beta114-Gln by Asn relaxes the steric constraints that prevent this reaction in the wild-type enzyme. This study reveals a new layer of structure-function interactions essential for reaction specificity in tryptophan synthase.

Literature references that cite this PDB file's key reference

  PubMed id Reference
19387555 S.Raboni, S.Bettati, and A.Mozzarelli (2009).
Tryptophan synthase: a mine for enzymologists.
  Cell Mol Life Sci, 66, 2391-2403.  
18486479 M.F.Dunn, D.Niks, H.Ngo, T.R.Barends, and I.Schlichting (2008).
Tryptophan synthase: the workings of a channeling nanomachine.
  Trends Biochem Sci, 33, 254-264.  
18675375 T.R.Barends, M.F.Dunn, and I.Schlichting (2008).
Tryptophan synthase, an allosteric molecular factory.
  Curr Opin Chem Biol, 12, 593-600.  
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