c-Src/Lyn kinases activate Helicobacter pylori CagA through tyrosine phosphorylation of the EPIYA motifs

Mol Microbiol. 2002 Feb;43(4):971-80. doi: 10.1046/j.1365-2958.2002.02781.x.


The human pathogen Helicobacter pylori colonizes the mucous layer of the stomach. During parasitic infection, freely swimming bacteria adhere to the gastric epithelial cells and trigger intracellular signalling pathways. This process requires the translocation of the effector protein CagA into the host cell through a specialized type IV secretion system encoded in the cag pathogenicity island. Following transfer, CagA is phosphorylated on tyrosine residues by a host cell kinase. Here, we describe how the tyrosine phosphorylation of CagA is restricted to a previously identified repeated sequence called D1. This sequence is located in the C-terminal half of the protein and contains the five-amino-acid motif EPIYA, which is amplified by duplications in a large fraction of clinical isolates. Tyrosine phosphorylation of CagA is essential for the activation process that leads to dramatic changes in the morphology of cells growing in culture. In addition, we observed that two members of the src kinases family, c-Src and Lyn, account for most of the CagA-specific kinase activity in host cell lysates. Thus, CagA translocation followed by tyrosine phosphorylation at the EPIYA motifs promotes a growth factor-like response with intense cytoskeletal rearrangements, cell elongation effects and increased cellular motility.

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Antigens, Bacterial*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • CSK Tyrosine-Protein Kinase
  • Helicobacter pylori / genetics
  • Helicobacter pylori / metabolism*
  • Molecular Sequence Data
  • Phosphorylation
  • Protein-Tyrosine Kinases / metabolism*
  • Pyrazoles / pharmacology
  • Pyrimidines / pharmacology
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods
  • Tyrosine / genetics
  • Tyrosine / metabolism*
  • src-Family Kinases / antagonists & inhibitors
  • src-Family Kinases / metabolism*


  • 4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine
  • Antigens, Bacterial
  • Bacterial Proteins
  • Pyrazoles
  • Pyrimidines
  • cagA protein, Helicobacter pylori
  • Tyrosine
  • Protein-Tyrosine Kinases
  • CSK Tyrosine-Protein Kinase
  • lyn protein-tyrosine kinase
  • src-Family Kinases
  • CSK protein, human