Recognition specificity for the bacterial avirulence protein AvrPto is determined by Thr-204 in the activation loop of the tomato Pto kinase.
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.
Frederick
R D
RD
Department of Agronomy, Lilly Hall of Life Sciences, Purdue University, West Lafayette, Indiana 47907-1150, USA.
Thilmony
R L
RL
Sessa
G
G
Martin
G B
GB
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism / Q000472:pathogenicity; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012231:Rhizobium / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics; D014774:Virulence
D001426:Bacterial Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C081695:avrPto protein, Pseudomonas syringae; C084354:Pto protein, Lycopersicon; D017346:Protein Serine-Threonine Kinases