Toxin-induced activation of the G protein p21 Rho by deamidation of glutamine

Nature. 1997 Jun 12;387(6634):729-33. doi: 10.1038/42743.


Pathogenic Escherichia coli are responsible for a variety of diseases, including diarrhoea, haemolytic uraemic syndrome, kidney infection, septicaemia, pneumonia and meningitis. Toxins called cytotoxic necrotizing factors (CNFs) are among the virulence factors produced by uropathogenic (CNF1) or enteropathogenic (CNF2) E. coli strains that cause diseases in humans and animals, respectively. CNFs induce an increase in the content of actin stress fibres and focal contacts in cultured cells. Effects of CNFs on the actin cytoskeleton correlated with a decrease in the electrophoretic mobility of the GTP-binding protein Rho and indirect evidence indicates that CNF1 might constitutively activate Rho. Here we show that CNF1 catalyses the deamidation of a glutamine residue at position 63 of Rho, turning it into glutamic acid, which inhibits both intrinsic GTP hydrolysis and that stimulated by its GTPase-activating protein (GAP). Thus, this deamidation of glutamine 63 by CNF1 leads to the constitutive activation of Rho, and induces the reorganization of actin stress fibres. To our knowledge, CNF1 is the first example of a bacterial toxin acting by deamidation of a specific target protein.

MeSH terms

  • Actins / metabolism
  • Amino Acid Sequence
  • Animals
  • Bacterial Toxins / pharmacology*
  • Chlorocebus aethiops
  • Cytoskeleton / drug effects
  • Cytoskeleton / metabolism
  • Cytotoxins / pharmacology*
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli
  • Escherichia coli Proteins*
  • GTP Phosphohydrolases / antagonists & inhibitors
  • GTP Phosphohydrolases / metabolism
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / metabolism*
  • GTPase-Activating Proteins*
  • Glutamine / metabolism*
  • Guanosine Triphosphate / metabolism
  • Kinetics
  • Molecular Sequence Data
  • Vero Cells
  • rho GTP-Binding Proteins
  • rhoA GTP-Binding Protein


  • Actins
  • Bacterial Toxins
  • Cytotoxins
  • Escherichia coli Proteins
  • GTPase-Activating Proteins
  • rho GTPase-activating protein
  • Glutamine
  • cytotoxic necrotizing factor type 1
  • Guanosine Triphosphate
  • GTP Phosphohydrolases
  • GTP-Binding Proteins
  • rho GTP-Binding Proteins
  • rhoA GTP-Binding Protein