2QGF

Structure of regulatory chain mutant H20A of asparate transcarbamoylase from E. coli


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.197 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Comparison of two T-state structures of regulatory-chain mutants of Escherichia coli aspartate transcarbamoylase suggests that His20 and Asp19 modulate the response to heterotropic effectors.

Stec, B.Williams, M.K.Stieglitz, K.A.Kantrowitz, E.R.

(2007) Acta Crystallogr.,Sect.D 63: 1243-1253

  • DOI: 10.1107/S0907444907052985
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Asp19 and His20 of Escherichia coli aspartate transcarbamoylase (EC 2.1.3.2) function in the binding of the triphosphate and ribose moieties of ATP and CTP and thereby may mediate important heterotropic regulation. The roles of these residues were in ...

    Asp19 and His20 of Escherichia coli aspartate transcarbamoylase (EC 2.1.3.2) function in the binding of the triphosphate and ribose moieties of ATP and CTP and thereby may mediate important heterotropic regulation. The roles of these residues were investigated by individually mutating each of them to alanine and determining both the kinetic parameters and the structures of the mutant enzymes. The structures were determined by X-ray crystallography at 2.15 and 2.75 A resolution for His20Ar and Asp19Ar, respectively. Analysis was carried out on the unliganded T-state form. The structures of the mutants did not show gross structural divergence from the canonical T-state, but showed small and systematic differences that were analyzed by global conformational analysis. Structural analysis and comparison with other regulatory-chain mutants confirmed that the Asp19Ar mutant represents the stabilized T-state, while structural analysis of the His20Ar form indicated that it represents an equilibrium shifted towards the R-state. Global analysis of the Asp19Ar and His20Ar enzymes suggested a possible role as molecular modulators of the heterotropic effects caused by the binding of nucleotides at the regulatory site. These studies highlighted the structural determinants of T- or R-state stabilization. Additionally, application of the ;consensus modeling' methodology combined with high-resolution data allowed the determination of unclear structural features contributing to nucleotide specificity and the role of the N-termini of the regulatory chains.


    Organizational Affiliation

    Burnham Institute for Medical Research, La Jolla, CA 92037, USA. bstec@burnham.org




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Aspartate carbamoyltransferase catalytic chain
A, C
310Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: pyrB
EC: 2.1.3.2
Find proteins for P0A786 (Escherichia coli (strain K12))
Go to UniProtKB:  P0A786
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Aspartate carbamoyltransferase regulatory chain
B, D
153Escherichia coli (strain K12)Mutation(s): 1 
Gene Names: pyrI
Find proteins for P0A7F3 (Escherichia coli (strain K12))
Go to UniProtKB:  P0A7F3
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download SDF File 
Download CCD File 
B, D
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.197 
  • Space Group: P 3 2 1
Unit Cell:
Length (Å)Angle (°)
a = 122.280α = 90.00
b = 122.280β = 90.00
c = 142.490γ = 120.00
Software Package:
Software NamePurpose
X-PLORmodel building
SDMSdata scaling
SDMSdata collection
SDMSdata reduction
X-PLORrefinement
X-PLORphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-02-19
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Derived calculations, Version format compliance