1EKX

THE ISOLATED, UNREGULATED CATALYTIC TRIMER OF ASPARTATE TRANSCARBAMOYLASE COMPLEXED WITH BISUBSTRATE ANALOG PALA (N-(PHOSPHONACETYL)-L-ASPARTATE)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.171 
  • R-Value Observed: 0.171 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Binding of bisubstrate analog promotes large structural changes in the unregulated catalytic trimer of aspartate transcarbamoylase: implications for allosteric regulation induced cell migration.

Endrizzi, J.A.Beernink, P.T.Alber, T.Schachman, H.K.

(2000) Proc Natl Acad Sci U S A 97: 5077-5082

  • DOI: https://doi.org/10.1073/pnas.090087197
  • Primary Citation of Related Structures:  
    1EKX

  • PubMed Abstract: 

    A central problem in understanding enzyme regulation is to define the conformational states that account for allosteric changes in catalytic activity. For Escherichia coli aspartate transcarbamoylase (ATCase; EC) the active, relaxed (R state) holoenzyme is generally assumed to be represented by the crystal structure of the complex of the holoenzyme with the bisubstrate analog N-phosphonacetyl-L-aspartate (PALA). It is unclear, however, which conformational differences between the unliganded, inactive, taut (T state) holoenzyme and the PALA complex are attributable to localized effects of inhibitor binding as contrasted to the allosteric transition. To define the conformational changes in the isolated, nonallosteric C trimer resulting from the binding of PALA, we determined the 1.95-A resolution crystal structure of the C trimer-PALA complex. In contrast to the free C trimer, the PALA-bound trimer exhibits approximate threefold symmetry. Conformational changes in the C trimer upon PALA binding include ordering of two active site loops and closure of the hinge relating the N- and C-terminal domains. The C trimer-PALA structure closely resembles the liganded C subunits in the PALA-bound holoenzyme. This similarity suggests that the pronounced hinge closure and other changes promoted by PALA binding to the holoenzyme are stabilized by ligand binding. Consequently, the conformational changes attributable to the allosteric transition of the holoenzyme remain to be defined.


  • Organizational Affiliation

    Department of Molecular and Cell Biology and Virus Laboratory, University of California, Berkeley, CA 94720-3206, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ASPARTATE TRANSCARBAMOYLASE
A, B, C
311Escherichia coliMutation(s): 0 
EC: 2.1.3.2
UniProt
Find proteins for P0A786 (Escherichia coli (strain K12))
Explore P0A786 
Go to UniProtKB:  P0A786
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A786
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.171 
  • R-Value Observed: 0.171 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.12α = 90
b = 82.13β = 90
c = 252.51γ = 90
Software Package:
Software NamePurpose
TNTrefinement
REFMACrefinement
MOSFLMdata reduction
CCP4data scaling
TNTphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-05-12
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-07
    Changes: Data collection, Database references, Derived calculations