Biological Assembly 1  

 3D View: Structure | Ligand Interaction

Global Symmetry: Cyclic - C3  (3D View)
Global Stoichiometry: Homo 3-mer - A3 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 103.09 kDa 
• Atom Count: 7601 
• Modelled Residue Count: 880 
• Deposited Residue Count: 930 
• Unique protein chains: 1

3CSU

CATALYTIC TRIMER OF ESCHERICHIA COLI ASPARTATE TRANSCARBAMOYLASE

• DOI: 10.2210/pdb3CSU/pdb

• Classification: TRANSFERASE (CARBAMOYL-P, ASPARTATE)
• Organism(s): Escherichia coli K-12
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 1999-04-22 Released: 1999-05-11 
• Deposition Author(s): Beernink, P.T., Endrizzi, J.A., Alber, T., Schachman, H.K.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.88 Å
• R-Value Free: 0.291 
• R-Value Work: 0.190 

Literature

Assessment of the allosteric mechanism of aspartate transcarbamoylase based on the crystalline structure of the unregulated catalytic subunit.

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

(1999) Proc Natl Acad Sci U S A 96: 5388-5393

• PubMed: 10318893 
• DOI: 10.1073/pnas.96.10.5388
• Primary Citation of Related Structures:  
  3CSU


• PubMed Abstract: 
  

The lack of knowledge of the three-dimensional structure of the trimeric, catalytic (C) subunit of aspartate transcarbamoylase (ATCase) has impeded understanding of the allosteric regulation of this enzyme and left unresolved the mechanism by which the active, unregulated C trimers are inactivated on incorporation into the unliganded (taut or T state) holoenzyme. Surprisingly, the isolated C trimer, based on the 1.9-A crystal structure reported here, resembles more closely the trimers in the T state enzyme than in the holoenzyme:bisubstrate-analog complex, which has been considered as the active, relaxed (R) state enzyme. Unlike the C trimer in either the T state or bisubstrate-analog-bound holoenzyme, the isolated C trimer lacks 3-fold symmetry, and the active sites are partially disordered. The flexibility of the C trimer, contrasted to the highly constrained T state ATCase, suggests that regulation of the holoenzyme involves modulating the potential for conformational changes essential for catalysis. Large differences in structure between the active C trimer and the holoenzyme:bisubstrate-analog complex call into question the view that this complex represents the activated R state of ATCase.

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Organizational Affiliation: 

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

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
PROTEIN (ASPARTATE CARBAMOYLTRANSFERASE)	A, B, C	310	Escherichia coli K-12	Mutation(s): 0  Gene Names: pyrB, b4245, JW4204 EC: 2.1.3.2
Find proteins for P0A786 (Escherichia coli (strain K12)) Explore P0A786  Go to UniProtKB:  P0A786

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
CA	B, C	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.88 Å
• R-Value Free: 0.291 
• R-Value Work: 0.190 
• Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 56.12	α = 90
b = 82.54	β = 90
c = 210.52	γ = 90

Software Package:

Software Name	Purpose
AMoRE	phasing
TNT	refinement
MOSFLM	data reduction
CCP4	data scaling

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1999-04-22 
• Released Date: 1999-05-11 
Deposition Author(s): Beernink, P.T., Endrizzi, J.A., Alber, T., Schachman, H.K.

Revision History  

• Version 1.0: 1999-05-11
  Type: Initial release
  
• Version 1.1: 2008-04-26
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Source and taxonomy, Version format compliance