Recognition specificity for the bacterial avirulence protein AvrPto is determined by Thr-204 in the activation loop of the tomato Pto kinase

Mol Cell. 1998 Aug;2(2):241-5. doi: 10.1016/s1097-2765(00)80134-3.


The Pto kinase confers resistance in tomato to P. syringae pv. tomato strains expressing the AvrPto protein. Physical interaction of the Pto kinase and AvrPto protein in the plant cell initiates host defense responses. The recognition event between these two proteins is very specific; AvrPto does not interact with other closely related kinases, including the Fen kinase, which shares 80% amino acid identity with Pto. By using Pto-Fen chimeric proteins and site-directed mutagenesis, we found that Thr-204 is required for Pto interaction with AvrPto in a yeast two-hybrid system and for recognition specificity in a tobacco leaf transient assay. Substitution of Thr-204 into the Fen kinase allowed that kinase to interact with AvrPto and to confer an AvrPto-specific defense response in tobacco leaves. Thus, simple mutations appear capable of giving rise to new resistance gene specificities.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Bacterial Proteins / metabolism*
  • Binding Sites / genetics
  • Lycopersicon esculentum / enzymology*
  • Lycopersicon esculentum / genetics
  • Lycopersicon esculentum / microbiology
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Plant Proteins*
  • Plants, Genetically Modified
  • Plants, Toxic
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Pseudomonas / metabolism
  • Pseudomonas / pathogenicity
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Rhizobium / metabolism
  • Tobacco / genetics
  • Virulence


  • Bacterial Proteins
  • Plant Proteins
  • Recombinant Fusion Proteins
  • avrPto protein, Pseudomonas syringae
  • Pto protein, Lycopersicon
  • Protein-Serine-Threonine Kinases

Associated data

  • GENBANK/L08476
  • GENBANK/L76191
  • GENBANK/U37133
  • GENBANK/U47029
  • GENBANK/U67422