2IPO

E. coli Aspartate Transcarbamoylase complexed with N-phosphonacetyl-L-asparagine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.201 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Use of L-asparagine and N-phosphonacetyl-L-asparagine to investigate the linkage of catalysis and homotropic cooperativity in E. coli aspartate transcarbomoylase.

Cardia, J.P.Eldo, J.Xia, J.O'Day, E.M.Tsuruta, H.Gryncel, K.R.Kantrowitz, E.R.

(2008) Proteins 71: 1088-1096

  • DOI: 10.1002/prot.21760

  • PubMed Abstract: 
  • The mechanism of domain closure and the allosteric transition of Escherichia coli aspartate transcarbamoylase (ATCase) are investigated using L-Asn, in the presence of carbamoyl phosphate (CP), and N-phosphonacetyl-L-asparagine (PASN). ATCase was fou ...

    The mechanism of domain closure and the allosteric transition of Escherichia coli aspartate transcarbamoylase (ATCase) are investigated using L-Asn, in the presence of carbamoyl phosphate (CP), and N-phosphonacetyl-L-asparagine (PASN). ATCase was found to catalyze the carbamoylation of L-Asn with a K(m) of 122 mM and a maximal velocity 10-fold lower than observed with the natural substrate, L-Asp. As opposed to L-Asp, no cooperativity was observed with respect to L-Asn. Time-resolved small-angle X-ray scattering (SAXS) and fluorescence experiments revealed that the combination of CP and L-Asn did not convert the enzyme from the T to the R state. PASN was found to be a potent inhibitor of ATCase exhibiting a K(D) of 8.8 microM. SAXS experiments showed that PASN was able to convert the entire population of molecules to the R state. Analysis of the crystal structure of the enzyme in the presence of PASN revealed that the binding of PASN was similar to that of the R-state complex of ATCase with N-phosphonaceyl-L-aspartate, another potent inhibitor of the enzyme. The linking of CP and L-Asn into one molecule, PASN, correctly orients the asparagine moiety in the active site to induce domain closure and the allosteric transition. This entropic effect allows for the high affinity binding of PASN. However, the binding of L-Asn, in the presence of a saturating concentration of CP, does not induce the closure of the two domains of the catalytic chain, nor does the enzyme undergo the transition to the high-activity high- affinity R structure. These results imply that Arg229, which interacts with the beta-carboxylate of L-Asp, plays a critical role in the orientation of L-Asp in the active site and demonstrates the requirement of the beta-carboxylate of L-Asp in the mechanism of domain closure and the allosteric transition in E. coli ATCase.


    Organizational Affiliation

    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467-3807, 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 4 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
MAE
Query on MAE

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Download CCD File 
C
MALEIC ACID
C4 H4 O4
VZCYOOQTPOCHFL-UPHRSURJSA-N
 Ligand Interaction
MPD
Query on MPD

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Download CCD File 
A, C
(4S)-2-METHYL-2,4-PENTANEDIOL
C6 H14 O2
SVTBMSDMJJWYQN-YFKPBYRVSA-N
 Ligand Interaction
1IP
Query on 1IP

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Download CCD File 
A, C
N~2~-(PHOSPHONOACETYL)-L-ASPARAGINE
C6 H11 N2 O7 P
DDKQZYWRWCFCJX-VKHMYHEASA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
1IPKd: 8800 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.201 
  • Space Group: P 3 2 1
Unit Cell:
Length (Å)Angle (°)
a = 120.475α = 90.00
b = 120.475β = 90.00
c = 155.087γ = 120.00
Software Package:
Software NamePurpose
d*TREKdata processing
CrystalCleardata collection
CNSphasing
CNSrefinement
PDB_EXTRACTdata extraction
d*TREKdata scaling
d*TREKdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-08-28
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance