8FX1

Crystal structure of the Trypanosoma cruzi hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT), isoform D, bound to (R)-SerMe-ImmH Phosphonate

Summary for 8FX1

• Entry DOI: 10.2210/pdb8fx1/pdb
• Descriptor: Hypoxanthine-guanine phosphoribosyltransferase, [(3R)-4-hydroxy-3-{[(4-oxo-4,5-dihydro-3H-pyrrolo[3,2-d]pyrimidin-7-yl)methyl]amino}butyl]phosphonic acid (3 entities in total)
• Functional Keywords: hypoxanthine-guanine-xanthine phosphoribosyltransferase, inhibitor, hgxprt, transferase-inhibitor complex, transferase/inhibitor
• Biological source: Trypanosoma cruzi (strain CL Brener)
• Total number of polymer chains: 2
• Total formula weight: 52398.46

Authors

Hughes, R.,Meneely, K.M.,Glockzin, K.,Clinch, K.,Tyler, P.C.,Lamb, A.L.,Meek, T.D.,Katzfuss, A. (deposition date: 2023-01-23, release date: 2023-07-19, Last modification date: 2023-11-22)

Primary citation

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.
Kinetic and Structural Characterization of Trypanosoma cruzi Hypoxanthine-Guanine-Xanthine Phosphoribosyltransferases and Repurposing of Transition-State Analogue Inhibitors.
Biochemistry, 62:2182-2201, 2023

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. , 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. . possesses four HG(X)PRT isoforms. We previously reported the kinetic characterization and inhibition of two isoforms, HGPRTs, demonstrating their catalytic equivalence. Here, we characterize the two remaining isoforms, revealing nearly identical HGXPRT activities and identifying for the first time . enzymes with XPRT activity, clarifying their previous annotation. 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 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 HGPRT and HGXPRT concomitantly, which is an important feature when targeting essential enzymes with overlapping activities.

PubMed: 37418678
DOI: 10.1021/acs.biochem.3c00116

Experimental method

X-RAY DIFFRACTION (1.8 Å)