Computational discovery of picomolar Q(o) site inhibitors of cytochrome bc1 complex

J Am Chem Soc. 2012 Jul 11;134(27):11168-76. doi: 10.1021/ja3001908. Epub 2012 Jun 27.

Abstract

A critical challenge to the fragment-based drug discovery (FBDD) is its low-throughput nature due to the necessity of biophysical method-based fragment screening. Herein, a method of pharmacophore-linked fragment virtual screening (PFVS) was successfully developed. Its application yielded the first picomolar-range Q(o) site inhibitors of the cytochrome bc(1) complex, an important membrane protein for drug and fungicide discovery. Compared with the original hit compound 4 (K(i) = 881.80 nM, porcine bc(1)), the most potent compound 4f displayed 20 507-fold improved binding affinity (K(i) = 43.00 pM). Compound 4f was proved to be a noncompetitive inhibitor with respect to the substrate cytochrome c, but a competitive inhibitor with respect to the substrate ubiquinol. Additionally, we determined the crystal structure of compound 4e (K(i) = 83.00 pM) bound to the chicken bc(1) at 2.70 Å resolution, providing a molecular basis for understanding its ultrapotency. To our knowledge, this study is the first application of the FBDD method in the discovery of picomolar inhibitors of a membrane protein. This work demonstrates that the novel PFVS approach is a high-throughput drug discovery method, independent of biophysical screening techniques.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens
  • Crystallography, X-Ray
  • Drug Design*
  • Electron Transport Complex III / antagonists & inhibitors*
  • Electron Transport Complex III / chemistry*
  • Electron Transport Complex III / metabolism
  • Models, Molecular
  • Protein Binding
  • Small Molecule Libraries / chemistry*
  • Small Molecule Libraries / pharmacology*
  • Swine
  • Thermodynamics

Substances

  • Small Molecule Libraries
  • Electron Transport Complex III