1B4Q

Solution structure of human thioltransferase complex with glutathione


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 95 
  • Conformers Submitted: 21 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Reactivity of the human thioltransferase (glutaredoxin) C7S, C25S, C78S, C82S mutant and NMR solution structure of its glutathionyl mixed disulfide intermediate reflect catalytic specificity.

Yang, Y.Jao, S.Nanduri, S.Starke, D.W.Mieyal, J.J.Qin, J.

(1998) Biochemistry 37: 17145-17156

  • DOI: 10.1021/bi9806504

  • PubMed Abstract: 
  • Human thioltransferase (TTase) is a 12 kDa thiol-disulfide oxidoreductase that appears to play a critical role in maintaining the redox environment of the cell. TTase acts as a potent and specific reducing agent for protein-S-S-glutathione mixed disu ...

    Human thioltransferase (TTase) is a 12 kDa thiol-disulfide oxidoreductase that appears to play a critical role in maintaining the redox environment of the cell. TTase acts as a potent and specific reducing agent for protein-S-S-glutathione mixed disulfides (protein-SSG) likely formed during oxidative stress or as redox intermediates in signal transduction pathways. Accordingly, the catalytic cycle of thioltransferase itself involves a covalent glutathionyl enzyme disulfide intermediate (TTase-C22-SSG). To understand the molecular basis of TTase specificity for the glutathione moiety, we engineered a quadruple Cys to Ser mutant of human TTase (C7S, C25S, C78S, and C82S) which retains only the active site cysteine residue (C22), and we solved its high-resolution NMR solution structure in the mixed disulfide intermediate with glutathione (QM-TTase-SSG). This mutant which cannot form a C22-S-S-C25 intramolecular disulfide displays the same catalytic efficiency (Vmax/KM) and specificity for glutathionyl mixed disulfide substrates as wild-type TTase, indicating that the Cys-25-SH moiety is not required for catalysis or glutathionyl specificity. The structure of human thioltransferase is characterized by a thioredoxin-like fold which comprises a four-stranded central beta-sheet flanked on each side by alpha-helices. The disulfide-adducted glutathione in the TTase-SSG complex has an extended conformation and is localized in a cleft near the protein surface encompassing the residues from helices-alpha2,alpha3, the active site loop, and the loop connecting helix-alpha3 and strand-beta3. Numerous van der Waals and electrostatic interactions between the protein and the glutathione moiety are identified as contributing to stabilization of the complex and confering the substrate specificity. Comparison of the human thioltransferase with other thiol-disulfide oxidoreductases reveals structural and functional differences.


    Organizational Affiliation

    Structural Biology Program, Department of Molecular Cardiology, Lerner Research Institute, The Cleveland Clinic Foundation, Ohio 44195, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
PROTEIN (HUMAN THIOLTRANSFERASE)
A
105Homo sapiensMutation(s): 4 
Gene Names: GLRX (GRX)
Find proteins for P35754 (Homo sapiens)
Go to Gene View: GLRX
Go to UniProtKB:  P35754
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GSH
Query on GSH

Download SDF File 
Download CCD File 
A
GLUTATHIONE
C10 H17 N3 O6 S
RWSXRVCMGQZWBV-WDSKDSINSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 95 
  • Conformers Submitted: 21 
  • Olderado: 1B4Q Olderado

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1999-12-23
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance