2GN0

Crystal structure of dimeric biodegradative threonine deaminase (TdcB) from Salmonella typhimurium at 1.7 A resolution (Triclinic form with one complete subunit built in alternate conformation)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.188 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structures of Salmonella typhimurium biodegradative threonine deaminase and its complex with CMP provide structural insights into ligand-induced oligomerization and enzyme activation.

Simanshu, D.K.Savithri, H.S.Murthy, M.R.

(2006) J.Biol.Chem. 281: 39630-39641

  • DOI: 10.1074/jbc.M605721200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Two different pyridoxal 5'-phosphate-containing l-threonine deaminases (EC 4.3.1.19), biosynthetic and biodegradative, which catalyze the deamination of l-threonine to alpha-ketobutyrate, are present in Escherichia coli and Salmonella typhimurium. Bi ...

    Two different pyridoxal 5'-phosphate-containing l-threonine deaminases (EC 4.3.1.19), biosynthetic and biodegradative, which catalyze the deamination of l-threonine to alpha-ketobutyrate, are present in Escherichia coli and Salmonella typhimurium. Biodegradative threonine deaminase (TdcB) catalyzes the first reaction in the anaerobic breakdown of l-threonine to propionate. TdcB, unlike the biosynthetic threonine deaminase, is insensitive to l-isoleucine and is activated by AMP. In the present study, TdcB from S. typhimurium was cloned and overexpressed in E. coli. In the presence of AMP or CMP, the recombinant enzyme was converted to the tetrameric form accompanied by significant enzyme activation. To provide insights into ligand-mediated oligomerization and enzyme activation, crystal structures of S. typhimurium TdcB and its complex with CMP were determined. In the native structure, TdcB is in a dimeric form, whereas in the TdcB.CMP complex, it exists in a tetrameric form with 222 symmetry and appears as a dimer of dimers. Tetrameric TdcB binds to four molecules of CMP, two at each of the dimer interfaces. Comparison of the dimer structure in the ligand (CMP)-free and -bound forms suggests that the changes induced by ligand binding at the dimer interface are essential for tetramerization. The differences observed in the tertiary and quaternary structures of TdcB in the absence and presence of CMP appear to account for enzyme activation and increased binding affinity for l-threonine. Comparison of TdcB with related pyridoxal 5'-phosphate-dependent enzymes points to structural and mechanistic similarities.


    Related Citations: 
    • Crystallization and preliminary X-ray crystallographic analysis of biodegradative threonine deaminase (TdcB) from Salmonella typhimurium
      Simanshu, D.K.,Chittori, S.,Savithri, H.S.,Murthy, M.R.
      (2006) Acta Crystallogr.,Sect.F 62: 275


    Organizational Affiliation

    Molecular Biophysics Unit, Malleswaram, Bangalore, Karnataka 560 012, India.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Threonine dehydratase catabolic
A, B, C, D
342Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)Mutation(s): 0 
Gene Names: tdcB
EC: 4.3.1.19
Find proteins for P11954 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Go to UniProtKB:  P11954
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

Download SDF File 
Download CCD File 
A, C
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
LLP
Query on LLP
A, B, C, D
L-PEPTIDE LINKINGC14 H22 N3 O7 PLYS
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.188 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 56.675α = 66.12
b = 76.827β = 89.16
c = 78.501γ = 77.08
Software Package:
Software NamePurpose
SCALEPACKdata scaling
AMoREphasing
REFMACrefinement
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-11-07
    Type: Initial release
  • Version 1.1: 2008-05-01
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Advisory, Refinement description, Version format compliance