3DAU

Crystal structure of the ternary MTX NADPH complex of Escherichia coli dihydrofolate reductase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.186 
  • R-Value Work: 0.159 
  • R-Value Observed: 0.160 

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Ligand Structure Quality Assessment 


This is version 1.3 of the entry. See complete history


Literature

X-ray structure of the ternary MTX.NADPH complex of the anthrax dihydrofolate reductase: a pharmacophore for dual-site inhibitor design.

Bennett, B.C.Wan, Q.Ahmad, M.F.Langan, P.Dealwis, C.G.

(2009) J Struct Biol 166: 162-171

  • DOI: 10.1016/j.jsb.2009.01.001
  • Primary Citation of Related Structures:  
    3DAT, 3DAU

  • PubMed Abstract: 
  • For reasons of bioterrorism and drug resistance, it is imperative to identify and develop new molecular points of intervention against anthrax. Dihydrofolate reductase (DHFR) is a highly conserved enzyme and an established target in a number of species for a variety of chemotherapeutic programs ...

    For reasons of bioterrorism and drug resistance, it is imperative to identify and develop new molecular points of intervention against anthrax. Dihydrofolate reductase (DHFR) is a highly conserved enzyme and an established target in a number of species for a variety of chemotherapeutic programs. Recently, the crystal structure of Bacillus anthracis DHFR (baDHFR) in complex with methotrexate (MTX) was determined and, based on the structure, proposals were made for drug design strategies directed against the substrate-binding site. However, little is gleaned about the binding site for NADPH, the cofactor responsible for hydride transfer in the catalytic mechanism. In the present study, X-ray crystallography at 100 K was used to determine the structure of baDHFR in complex with MTX and NADPH. Although the NADPH binding mode is nearly identical to that seen in other DHFR ternary complex structures, the adenine moiety adopts an off-plane tilt of nearly 90 degrees and this orientation is stabilized by hydrogen bonds to functionally conserved Arg residues. A comparison of the binding site, focusing on this region, between baDHFR and the human enzyme is discussed, with an aim at designing species-selective therapeutics. Indeed, the ternary model, refined to 2.3 A resolution, provides an accurate template for testing the feasibility of identifying dual-site inhibitors, compounds that target both the substrate and cofactor-binding site. With the ternary model in hand, using in silico methods, several compounds were identified which could potentially form key bonding contacts in the substrate and cofactor-binding sites. Ultimately, two structurally distinct compounds were verified that inhibit baDHFR at low microM concentrations. The apparent Kd for one of these, (2-(3-(2-(hydroxyimino)-2-(pyridine-4-yl)-6,7-dimethylquinoxalin-2-yl)-1-(pyridine-4-yl)ethanone oxime), was measured by fluorescence spectroscopy to be 5.3 microM.


    Organizational Affiliation

    Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4965, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Dihydrofolate reductaseA159Escherichia coli K-12Mutation(s): 0 
Gene Names: folAtmrAb0048JW0047
EC: 1.5.1.3
UniProt
Find proteins for P0ABQ4 (Escherichia coli (strain K12))
Explore P0ABQ4 
Go to UniProtKB:  P0ABQ4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0ABQ4
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NDP
Query on NDP

Download Ideal Coordinates CCD File 
C [auth A]NADPH DIHYDRO-NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE
C21 H30 N7 O17 P3
ACFIXJIJDZMPPO-NNYOXOHSSA-N
 Ligand Interaction
MTX
Query on MTX

Download Ideal Coordinates CCD File 
B [auth A]METHOTREXATE
C20 H22 N8 O5
FBOZXECLQNJBKD-ZDUSSCGKSA-N
 Ligand Interaction
Binding Affinity Annotations 
IDSourceBinding Affinity
MTX BindingDB:  3DAU IC50: min: 3, max: 8.8 (nM) from 3 assay(s)
EC50: 1 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.186 
  • R-Value Work: 0.159 
  • R-Value Observed: 0.160 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 61.847α = 90
b = 61.847β = 90
c = 104.74γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
REFMACrefinement
PDB_EXTRACTdata extraction
BioCARSdata collection
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-04-14
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.2: 2013-11-20
    Changes: Non-polymer description
  • Version 1.3: 2017-10-25
    Changes: Refinement description