8FX2

Crystal structure of the Trypanosoma cruzi hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT), isoform D, bound to Immucillin-HP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.54 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.184 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Kinetic and Structural Characterization of Trypanosoma cruzi Hypoxanthine-Guanine-Xanthine Phosphoribosyltransferases and Repurposing of Transition-State Analogue Inhibitors.

Glockzin, K.Meneely, K.M.Hughes, R.Maatouk, S.W.Pina, G.E.Suthagar, K.Clinch, K.Buckler, J.N.Lamb, A.L.Tyler, P.C.Meek, T.D.Katzfuss, A.

(2023) Biochemistry 62: 2182-2201

  • DOI: https://doi.org/10.1021/acs.biochem.3c00116
  • Primary Citation of Related Structures:  
    8FWY, 8FWZ, 8FX0, 8FX1, 8FX2, 8FX3

  • PubMed Abstract: 

    Over 70 million people are currently at risk of developing Chagas Disease (CD) infection, with more than 8 million people already infected worldwide. Current treatments are limited and innovative therapies are required. Trypanosoma cruzi , the etiological agent of CD, is a purine auxotroph that relies on phosphoribosyltransferases to salvage purine bases from their hosts for the formation of purine nucleoside monophosphates. Hypoxanthine-guanine-xanthine phosphoribosyltransferases (HGXPRTs) catalyze the salvage of 6-oxopurines and are promising targets for the treatment of CD. HGXPRTs catalyze the formation of inosine, guanosine, and xanthosine monophosphates from 5-phospho-d-ribose 1-pyrophosphate and the nucleobases hypoxanthine, guanine, and xanthine, respectively. T . cruzi possesses four HG(X)PRT isoforms. We previously reported the kinetic characterization and inhibition of two isoforms, Tc HGPRTs, demonstrating their catalytic equivalence. Here, we characterize the two remaining isoforms, revealing nearly identical HGXPRT activities in vitro and identifying for the first time T . cruzi enzymes with XPRT activity, clarifying their previous annotation. Tc HGXPRT follows an ordered kinetic mechanism with a postchemistry event as the rate-limiting step(s) of catalysis. Its crystallographic structures reveal implications for catalysis and substrate specificity. A set of transition-state analogue inhibitors (TSAIs) initially developed to target the malarial orthologue were re-evaluated, with the most potent compound binding to Tc HGXPRT with nanomolar affinity, validating the repurposing of TSAIs to expedite the discovery of lead compounds against orthologous enzymes. We identified mechanistic and structural features that can be exploited in the optimization of inhibitors effective against Tc HGPRT and Tc HGXPRT concomitantly, which is an important feature when targeting essential enzymes with overlapping activities.


  • Organizational Affiliation

    Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Boulevard, College Station, Texas 77843-2128, United States.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Hypoxanthine-guanine phosphoribosyltransferase
A, B
231Trypanosoma cruzi strain CL BrenerMutation(s): 0 
Gene Names: ECC02_007666
EC: 2.4.2.8
UniProt
Find proteins for Q4DGA2 (Trypanosoma cruzi (strain CL Brener))
Explore Q4DGA2 
Go to UniProtKB:  Q4DGA2
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ4DGA2
Sequence Annotations
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  • Reference Sequence
Small Molecules
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.54 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.184 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.083α = 90
b = 80.478β = 90
c = 89.877γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
XSCALEdata scaling
PHENIXphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)United StatesAI127807

Revision History  (Full details and data files)

  • Version 1.0: 2023-07-19
    Type: Initial release
  • Version 1.1: 2023-07-26
    Changes: Database references
  • Version 1.2: 2023-10-25
    Changes: Data collection, Refinement description
  • Version 1.3: 2023-11-22
    Changes: Source and taxonomy