1K97

Crystal Structure of E. coli Argininosuccinate Synthetase in complex with Aspartate and Citrulline


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 
    0.214 (Depositor) 
  • R-Value Work: 
    0.176 (Depositor), 0.170 (DCC) 
  • R-Value Observed: 
    0.176 (Depositor) 

Starting Model: experimental
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Ligand Structure Quality Assessment 

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Literature

The 1.6 A crystal structure of E. coli argininosuccinate synthetase suggests a conformational change during catalysis.

Lemke, C.T.Howell, P.L.

(2001) Structure 9: 1153-1164

  • DOI: https://doi.org/10.1016/s0969-2126(01)00683-9
  • Primary Citation of Related Structures:  
    1K92, 1K97

  • PubMed Abstract: 

    Argininosuccinate synthetase (AS) is the rate-limiting enzyme of both the urea and arginine-citrulline cycles. In mammals, deficiency of AS leads to citrullinemia, a debilitating and often fatal autosomal recessive urea cycle disorder, whereas its overexpression for sustained nitric oxide production via the arginine-citrulline cycle leads to the potentially fatal hypotension associated with septic and cytokine-induced circulatory shock. The crystal structure of E. coli AS (EAS) has been determined by the use of selenomethionine incorporation and MAD phasing. The structure has been refined at 1.6 A resolution in the absence of its substrates and at 2.0 A in the presence of aspartate and citrulline (EAS*CIT+ASP). Each monomer of this tetrameric protein has two structural domains: a nucleotide binding domain similar to that of the "N-type" ATP pyrophosphatase class of enzymes, and a novel catalytic/multimerization domain. The EAS*CIT+ASP structure clearly describes the binding of citrulline at the cleft between the two domains and of aspartate to a loop of the nucleotide binding domain, whereas homology modeling with the N-type ATP pyrophosphatases has provided the location of ATP binding. The first three-dimensional structures of AS are reported. The fold of the nucleotide binding domain confirms AS as the fourth structurally defined member of the N-type ATP pyrophosphatases. The structures identify catalytically important residues and suggest the requirement for a conformational change during the catalytic cycle. Sequence similarity between the bacterial and human enzymes has been used for providing insight into the structural and functional effects of observed clinical mutations.


  • Organizational Affiliation

    Structural Biology and Biochemistry, Research Institute, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ARGININOSUCCINATE SYNTHASE455Escherichia coliMutation(s): 0 
Gene Names: ARGG
EC: 6.3.4.5
UniProt
Find proteins for P0A6E4 (Escherichia coli (strain K12))
Explore P0A6E4 
Go to UniProtKB:  P0A6E4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A6E4
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free:  0.214 (Depositor) 
  • R-Value Work:  0.176 (Depositor), 0.170 (DCC) 
  • R-Value Observed: 0.176 (Depositor) 
Space Group: I 2 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 77.996α = 90
b = 105.336β = 90
c = 127.36γ = 90
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling
CNSphasing

Structure Validation

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Ligand Structure Quality Assessment 

Created with Raphaël 2.3.0Worse 01 BetterLigand structure goodness of fit to experimental dataBest fitted CIRClick on this verticalbar to view details

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2001-12-07
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 2.0: 2023-08-16
    Changes: Atomic model, Data collection, Database references, Derived calculations, Refinement description
  • Version 3.0: 2023-11-15
    Changes: Atomic model, Data collection