Antitumor antibiotic fostriecin covalently binds to cysteine-269 residue of protein phosphatase 2A catalytic subunit in mammalian cells

Bioorg Med Chem. 2009 Dec 1;17(23):8113-22. doi: 10.1016/j.bmc.2009.09.050. Epub 2009 Oct 3.


Fostriecin is a phosphate monoester with excellent antitumor activity against mouse leukemia, and it is a potent inhibitor of protein phosphatase (PP) 2A. This compound has been predicted to covalently bind to the Cys269 residue of the PP2A catalytic subunit (PP2Ac) at the alpha,beta-unsaturated lactone via a conjugate addition reaction. However, this binding has not yet been experimentally proven. To confirm such binding, we synthesized biotin-labeled fostriecin (bio-Fos), which has an inhibitory activity against the proliferation of mouse leukemia cells. We showed that fostriecin directly binds to PP2Ac in HeLa S3 cells by pull-down assays using bio-Fos. Moreover, we directly demonstrated that fostriecin covalently binds to the Cys269 residue of PP2Ac by matrix assisted laser desorption/ionization time-of-flight mass spectrometry analysis. From these results, the inhibitory mechanism of fostriecin on PP2A activity is discussed.

MeSH terms

  • Alkenes / pharmacology*
  • Amino Acid Sequence
  • Antibiotics, Antineoplastic / pharmacology*
  • Binding Sites / physiology
  • Binding, Competitive / physiology
  • Catalytic Domain / physiology
  • Cell Survival / physiology
  • Cysteine / metabolism*
  • HeLa Cells
  • Humans
  • Inhibitory Concentration 50
  • Magnetic Resonance Spectroscopy
  • Models, Molecular*
  • Molecular Sequence Data
  • Polyenes
  • Protein Phosphatase 2 / metabolism*
  • Pyrones / pharmacology*
  • Spectrometry, Mass, Electrospray Ionization
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Spectroscopy, Fourier Transform Infrared


  • Alkenes
  • Antibiotics, Antineoplastic
  • Polyenes
  • Pyrones
  • Protein Phosphatase 2
  • Cysteine
  • fostriecin