4DB7

Crystal structure of B. anthracis DHPS with compound 25


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.270 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.233 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


Ligand Structure Quality Assessment 


This is version 1.3 of the entry. See complete history


Literature

Structure-Based Design of Novel Pyrimido[4,5-c]pyridazine Derivatives as Dihydropteroate Synthase Inhibitors with Increased Affinity.

Zhao, Y.Hammoudeh, D.Yun, M.K.Qi, J.White, S.W.Lee, R.E.

(2012) ChemMedChem 7: 861-870

  • DOI: https://doi.org/10.1002/cmdc.201200049
  • Primary Citation of Related Structures:  
    4D8A, 4D8Z, 4D9P, 4DAF, 4DAI, 4DB7

  • PubMed Abstract: 

    Dihydropteroate synthase (DHPS) is the validated drug target for sulfonamide antimicrobial therapy. However, due to widespread drug resistance and poor tolerance, the use of sulfonamide antibiotics is now limited. The pterin binding pocket in DHPS is highly conserved and is distinct from the sulfonamide binding site. It therefore represents an attractive alternative target for the design of novel antibacterial agents. We previously carried out the structural characterization of a known pyridazine inhibitor in the Bacillus anthracis DHPS pterin site and identified a number of unfavorable interactions that appear to compromise binding. With this structural information, a series of 4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-c]pyridazines were designed to improve binding affinity. Most importantly, the N-methyl ring substitution was removed to improve binding within the pterin pocket, and the length of the side chain carboxylic acid was optimized to fully engage the pyrophosphate binding site. These inhibitors were synthesized and evaluated by an enzyme activity assay, X-ray crystallography, isothermal calorimetry, and surface plasmon resonance to obtain a comprehensive understanding of the binding interactions from structural, kinetic, and thermodynamic perspectives. This study clearly demonstrates that compounds lacking the N-methyl substitution exhibit increased inhibition of DHPS, but the beneficial effects of optimizing the side chain length are less apparent.


  • Organizational Affiliation

    Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Dihydropteroate Synthase
A, B
297Bacillus anthracis str. A2012Mutation(s): 0 
Gene Names: folP
EC: 2.5.1.15
UniProt
Find proteins for Q81VW8 (Bacillus anthracis)
Explore Q81VW8 
Go to UniProtKB:  Q81VW8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ81VW8
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Z25
Query on Z25

Download Ideal Coordinates CCD File 
C [auth A],
H [auth B]
3-(7-amino-4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-c]pyridazin-3-yl)propanoic acid
C9 H9 N5 O4
CGUTUVAIFLDCOT-UHFFFAOYSA-N
SO4
Query on SO4

Download Ideal Coordinates CCD File 
D [auth A]
E [auth A]
F [auth A]
G [auth A]
I [auth B]
D [auth A],
E [auth A],
F [auth A],
G [auth A],
I [auth B],
J [auth B],
K [auth B],
L [auth B],
M [auth B]
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
Binding Affinity Annotations 
IDSourceBinding Affinity
Z25 PDBBind:  4DB7 Kd: 273 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.270 
  • R-Value Work: 0.232 
  • R-Value Observed: 0.233 
  • Space Group: P 62 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 99.695α = 90
b = 99.695β = 90
c = 263.431γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
REFMACrefinement
PDB_EXTRACTdata extraction
SERGUIdata collection
HKL-2000data reduction
HKL-2000data 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: 2012-03-28
    Type: Initial release
  • Version 1.1: 2012-05-09
    Changes: Database references
  • Version 1.2: 2017-11-15
    Changes: Refinement description
  • Version 1.3: 2023-09-13
    Changes: Data collection, Database references, Derived calculations, Refinement description