4X5A

Anthranilate phosphoribosyltransferase variant R193A from Mycobacterium tuberculosis remains ligand-free when co-crystallised with PRPP and Mg


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.93 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.238 
  • R-Value Observed: 0.241 

Starting Model: experimental
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This is version 1.1 of the entry. See complete history


Literature

Structures of Mycobacterium tuberculosis Anthranilate Phosphoribosyltransferase Variants Reveal the Conformational Changes That Facilitate Delivery of the Substrate to the Active Site.

Cookson, T.V.Evans, G.L.Castell, A.Baker, E.N.Lott, J.S.Parker, E.J.

(2015) Biochemistry 54: 6082-6092

  • DOI: https://doi.org/10.1021/acs.biochem.5b00612
  • Primary Citation of Related Structures:  
    4X58, 4X59, 4X5A, 4X5B, 4X5C, 4X5D, 4X5E

  • PubMed Abstract: 

    Anthranilate phosphoribosyltransferase (AnPRT) is essential for the biosynthesis of tryptophan in Mycobacterium tuberculosis (Mtb). This enzyme catalyzes the second committed step in tryptophan biosynthesis, the Mg²⁺-dependent reaction between 5'-phosphoribosyl-1'-pyrophosphate (PRPP) and anthranilate. The roles of residues predicted to be involved in anthranilate binding have been tested by the analysis of six Mtb-AnPRT variant proteins. Kinetic analysis showed that five of six variants were active and identified the conserved residue R193 as being crucial for both anthranilate binding and catalytic function. Crystal structures of these Mtb-AnPRT variants reveal the ability of anthranilate to bind in three sites along an extended anthranilate tunnel and expose the role of the mobile β2-α6 loop in facilitating the enzyme's sequential reaction mechanism. The β2-α6 loop moves sequentially between a "folded" conformation, partially occluding the anthranilate tunnel, via an "open" position to a "closed" conformation, which supports PRPP binding and allows anthranilate access via the tunnel to the active site. The return of the β2-α6 loop to the "folded" conformation completes the catalytic cycle, concordantly allowing the active site to eject the product PRA and rebind anthranilate at the opening of the anthranilate tunnel for subsequent reactions. Multiple anthranilate molecules blocking the anthranilate tunnel prevent the β2-α6 loop from undergoing the conformational changes required for catalysis, thus accounting for the unusual substrate inhibition of this enzyme.


  • Organizational Affiliation

    Maurice Wilkins Centre for Molecular Biodiscovery, Biomolecular Interaction Centre, and Department of Chemistry, University of Canterbury , 20 Kirkwood Avenue, Christchurch 8140, New Zealand.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Anthranilate phosphoribosyltransferase
A, B
378Mycobacterium tuberculosisMutation(s): 1 
Gene Names: trpD
EC: 2.4.2.18
UniProt
Find proteins for P9WFX5 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Explore P9WFX5 
Go to UniProtKB:  P9WFX5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP9WFX5
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.93 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.238 
  • R-Value Observed: 0.241 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 94.448α = 90
b = 77.779β = 111.84
c = 101.932γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
XDSdata reduction
PDB_EXTRACTdata extraction
Aimlessdata scaling
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-11-25
    Type: Initial release
  • Version 1.1: 2023-09-27
    Changes: Data collection, Database references, Derived calculations, Refinement description