4FYW

E. coli Aspartate Transcarbamoylase complexed with CTP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.184 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Metal Ion Involvement in the Allosteric Mechanism of Escherichia coli Aspartate Transcarbamoylase.

Cockrell, G.M.Kantrowitz, E.R.

(2012) Biochemistry 51: 7128-7137

  • DOI: 10.1021/bi300920m
  • Primary Citation of Related Structures:  4FYV, 4FYX, 4FYY

  • PubMed Abstract: 
  • Escherichia coli aspartate transcarbamoylase (ATCase) allosterically regulates pyrimidine nucleotide biosynthesis. The enzyme is inhibited by CTP and can be further inhibited by UTP, although UTP alone has little or no influence on activity; however, ...

    Escherichia coli aspartate transcarbamoylase (ATCase) allosterically regulates pyrimidine nucleotide biosynthesis. The enzyme is inhibited by CTP and can be further inhibited by UTP, although UTP alone has little or no influence on activity; however, the mechanism for the synergistic inhibition is still unknown. To determine how UTP is able to synergistically inhibit ATCase in the presence of CTP, we determined a series of X-ray structures of ATCase·nucleotide complexes. Analysis of the X-ray structures revealed that (1) CTP and dCTP bind in a very similar fashion, (2) UTP, in the presence of dCTP or CTP, binds at a site that does not overlap the CTP/dCTP site, and (3) the triphosphates of the two nucleotides are parallel to each other with a metal ion, in this case Mg(2+), coordinated between the β- and γ-phosphates of the two nucleotides. Kinetic experiments showed that the presence of a metal ion such as Mg(2+) is required for synergistic inhibition. Together, these results explain how the binding of UTP can enhance the binding of CTP and why UTP binds more tightly in the presence of CTP. A mechanism for the synergistic inhibition of ATCase is proposed in which the presence of UTP stabilizes the T state even more than CTP alone. These results also call into question many of the past kinetic and binding experiments with ATCase with nucleotides as the presence of metal contamination was not considered important.


    Organizational Affiliation

    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Aspartate carbamoyltransferase catalytic chain
A, C
310Escherichia coli (strain K12)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)Gene Names: pyrI
Find proteins for P0A7F3 (Escherichia coli (strain K12))
Go to UniProtKB:  P0A7F3
Small Molecules
Ligands 2 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
CTP
Query on CTP

Download SDF File 
Download CCD File 
B, D
CYTIDINE-5'-TRIPHOSPHATE
C9 H16 N3 O14 P3
PCDQPRRSZKQHHS-XVFCMESISA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.184 
  • Space Group: P 3 2 1
Unit Cell:
Length (Å)Angle (°)
a = 121.297α = 90.00
b = 121.297β = 90.00
c = 142.251γ = 120.00
Software Package:
Software NamePurpose
PHENIXphasing
d*TREKdata reduction
PDB_EXTRACTdata extraction
d*TREKdata scaling
PHENIXrefinement
CrystalCleardata collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-10-10
    Type: Initial release