2J9Y

Tryptophan Synthase Q114N mutant in complex with Compound II


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.228 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Betaq114N and Betat110V Mutations Reveal a Critically Important Role of the Substrate Alpha-Carboxylate Site in the Reaction Specificity of Tryptophan Synthase.

Blumenstein, L.Domratcheva, T.Niks, D.Ngo, H.Seidel, R.Dunn, M.F.Schlichting, I.

(2007) Biochemistry 46: 14100

  • DOI: 10.1021/bi7008568
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • 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 relationshi ...

    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.


    Organizational Affiliation

    Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Heidelberg, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
TRYPTOPHAN SYNTHASE ALPHA CHAIN
A
268Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)Mutation(s): 0 
Gene Names: trpA
EC: 4.2.1.20
Find proteins for P00929 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Go to UniProtKB:  P00929
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
TRYPTOPHAN SYNTHASE BETA CHAIN
B
397Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)Mutation(s): 1 
Gene Names: trpB
EC: 4.2.1.20
Find proteins for P0A2K1 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Go to UniProtKB:  P0A2K1
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

Download SDF File 
Download CCD File 
B
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
FOO
Query on FOO

Download SDF File 
Download CCD File 
B
(3E)-4-{3-HYDROXY-2-METHYL-5-[(PHOSPHONOOXY)METHYL]PYRIDIN-4-YL}-2-IMINOBUT-3-ENOIC ACID
C11 H13 N2 O7 P
RFCLOBQLGFQJHL-LDEIZCIFSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.228 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 182.740α = 90.00
b = 60.700β = 94.83
c = 67.410γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
XDSdata reduction
XSCALEdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-12-04
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance