3GC5

tRNA-guanine transglycosylase in complex with 6-amino-4-(2-aminoethyl)-2-(methylamino)-1,7-dihydro-8H-imidazo[4,5-g]quinazolin-8-one


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.40 Å
  • R-Value Free: 0.192 
  • R-Value Observed: 0.162 

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Ligand Structure Quality Assessment 


This is version 1.2 of the entry. See complete history


Literature

How to Replace the Residual Solvation Shell of Polar Active Site Residues to Achieve Nanomolar Inhibition of tRNA-Guanine Transglycosylase

Ritschel, T.Kohler, P.C.Neudert, G.Heine, A.Diederich, F.Klebe, G.

(2009) ChemMedChem 4: 2012-2023

  • DOI: https://doi.org/10.1002/cmdc.200900343
  • Primary Citation of Related Structures:  
    3EOS, 3EOU, 3GC4, 3GC5, 3GE7

  • PubMed Abstract: 

    In a computational and structural study, we investigated a series of 4-substituted lin-benzoguanines that are potent inhibitors of tRNA-guanine transglycosylase (TGT), a putative target for the treatment of shigellosis. At first glance, it appears self-evident that the placement of a positively charged ligand functional group between the carboxylate groups of two adjacent aspartate residues in the glycosylase catalytic center leads to enhanced ligand binding. The concomitant displacement of water molecules that partially solvate the aspartates prior to ligand binding appears to result as a consequence of this. However, the case study presented herein shows that this premise is much too superficial. Placement of a likely positively charged amino group at such a pivotal position, interfering with the residual water solvation shell, is at best cost-neutral compared with the unsubstituted parent ligand not conflicting with the residual water shell. A ligand that orients a hydroxy group in this position shows even decreased binding. Based on the cost-neutral placement of the amino functionality, hydrophobic side chains can now be further attached to fill, with increasing potency, a small hydrophobic pocket remote to the aspartates. Any attempts to cross the pivotal position between both aspartates with nonpolar scaffolds reveals only decreased binding, even though the waters of the residual solvation shell are successfully repelled. This surprising observation fostered a detailed analysis of the role of water molecules involved in the residual solvation of polar active site residues. Their geometry and putative replacement in the binding pocket of TGT has been studied by a comparative database analysis, computational active site mapping, and a series of crystal structure analyses. Furthermore, conformational preferences of attached hydrophobic moieties explain their contribution to a gradual increase in binding affinity.


  • Organizational Affiliation

    Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6, 35032 Marburg, Germany.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Queuine tRNA-ribosyltransferase386Zymomonas mobilisMutation(s): 0 
Gene Names: tgtZMO0363
EC: 2.4.2.29
UniProt
Find proteins for P28720 (Zymomonas mobilis subsp. mobilis (strain ATCC 31821 / ZM4 / CP4))
Explore P28720 
Go to UniProtKB:  P28720
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP28720
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.40 Å
  • R-Value Free: 0.192 
  • R-Value Observed: 0.162 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 90.2α = 90
b = 65β = 96.2
c = 70.8γ = 90
Software Package:
Software NamePurpose
MxCuBEdata collection
CNSrefinement
SHELXL-97refinement
HKL-2000data reduction
HKL-2000data scaling
CNSphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-12-15
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.2: 2024-03-20
    Changes: Data collection, Database references, Derived calculations