Inosine Monophosphate Dehydrogenase (IMPDH) From Tritrichomonas Foetus with RVP and MOA bound

Experimental Data Snapshot

  • Resolution: 2.15 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.233 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.2 of the entry. See complete history


Crystal Structure of Tritrichomonas foetus Inosine Monophosphate Dehydrogenase in Complex with the Inhibitor Ribavirin Monophosphate Reveals a Catalysis-dependent Ion-binding Site

Prosise, G.L.Wu, J.Luecke, H.

(2002) J Biol Chem 277: 50654-50659

  • DOI: https://doi.org/10.1074/jbc.M208330200
  • Primary Citation of Related Structures:  
    1ME7, 1ME8

  • PubMed Abstract: 

    Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step in GMP biosynthesis. The resulting intracellular pool of guanine nucleotides is of great importance to all cells for use in DNA and RNA synthesis, metabolism, and signal transduction. The enzyme binds IMP and the cofactor NAD(+) in random order, IMP is converted to XMP, NAD(+) is reduced to NADH, and finally, NADH and then XMP are released sequentially. XMP is subsequently converted into GMP by GMP synthetase. Drugs that decrease GMP synthesis by inhibiting IMPDH have been shown to have antiproliferative as well as antiviral activity. Several drugs are in use that target the substrate- or cofactor-binding site; however, due to differences between the mammalian and microbial isoforms, most drugs are far less effective against the microbial form of the enzyme than the mammalian form. The high resolution crystal structures of the protozoan parasite Tritrichomonas foetus IMPDH complexed with the inhibitor ribavirin monophosphate as well as monophosphate together with a second inhibitor, mycophenolic acid, are presented here. These structures reveal an active site cation identified previously only in the Chinese hamster IMPDH structure with covalently bound IMP. This cation was not found previously in apo IMPDH, IMPDH in complex with XMP, or covalently bound inhibitor, indicating that the cation-binding site may be catalysis-dependent. A comparison of T. foetus IMPDH with the Chinese hamster and Streptococcus pyogenes structures reveals differences in the active site loop architecture, which contributes to differences in cation binding during the catalytic sequence and the kinetic rates between bacterial, protozoan, and mammalian enzymes. Exploitation of these differences may lead to novel inhibitors, which favor the microbial form of the enzyme.

  • Organizational Affiliation

    Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
INOSINE-5'-MONOPHOSPHATE DEHYDROGENASE503Tritrichomonas suisMutation(s): 0 
Gene Names: IMPDH
Find proteins for P50097 (Tritrichomonas foetus)
Explore P50097 
Go to UniProtKB:  P50097
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP50097
Sequence Annotations
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
RVP PDBBind:  1ME7 Ki: 65 (nM) from 1 assay(s)
Binding MOAD:  1ME7 Ki: 65 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 2.15 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.233 
  • Space Group: P 4 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 155.068α = 90
b = 155.068β = 90
c = 155.068γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-01-14
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance