Back to Search
Start Over
The N-terminal region of Pseudomonas type III effector AvrPtoB elicits Pto-dependent immunity and has two distinct virulence determinants.
- Source :
-
The Plant journal : for cell and molecular biology [Plant J] 2007 Nov; Vol. 52 (4), pp. 595-614. Date of Electronic Publication: 2007 Aug 31. - Publication Year :
- 2007
-
Abstract
- Resistance to bacterial speck disease in tomato is activated by the physical interaction of the host Pto kinase with either of the sequence-dissimilar type III effector proteins AvrPto or AvrPtoB (HopAB2) from Pseudomonas syringae pv. tomato. Pto-mediated immunity requires Prf, a protein with a nucleotide-binding site and leucine-rich repeats. The N-terminal 307 amino acids of AvrPtoB were previously reported to interact with the Pto kinase, and we show here that this region (AvrPtoB(1-307)) is sufficient for eliciting Pto/Prf-dependent immunity against P. s. pv. tomato. AvrPtoB(1-307) was also found to be sufficient for a virulence activity that enhances ethylene production and increases growth of P. s. pv. tomato and severity of speck disease on susceptible tomato lines lacking either Pto or Prf. Moreover, we found that residues 308-387 of AvrPtoB are required for the previously reported ability of AvrPtoB to suppress pathogen-associated molecular patterns-induced basal defenses in Arabidopsis. Thus, the N-terminal region of AvrPtoB has two structurally distinct domains involved in different virulence-promoting mechanisms. Random and targeted mutagenesis identified five tightly clustered residues in AvrPtoB(1-307) that are required for interaction with Pto and for elicitation of immunity to P. s. pv. tomato. Mutation of one of the five clustered residues abolished the ethylene-associated virulence activity of AvrPtoB(1-307). However, individual mutations of the other four residues, despite abolishing interaction with Pto and avirulence activity, had no effect on AvrPtoB(1-307) virulence activity. None of these mutations affected the basal defense-suppressing activity of AvrPtoB(1-387). Based on sequence alignments, estimates of helical propensity, and the previously reported structure of AvrPto, we hypothesize that the Pto-interacting domains of AvrPto and AvrPtoB(1-307) have structural similarity. Together, these data support a model in which AvrPtoB(1-307) promotes ethylene-associated virulence by interaction not with Pto but with another unknown host protein.
- Subjects :
- Amino Acid Sequence
Apoptosis genetics
Arabidopsis genetics
Arabidopsis metabolism
Arabidopsis microbiology
Bacterial Proteins chemistry
Bacterial Proteins genetics
Blotting, Western
Immunity, Innate genetics
Solanum lycopersicum genetics
Solanum lycopersicum metabolism
Solanum lycopersicum microbiology
Molecular Sequence Data
Mutagenesis
Plant Diseases genetics
Plant Proteins genetics
Polymerase Chain Reaction
Protein Binding
Protein Serine-Threonine Kinases genetics
Protein Structure, Tertiary
Pseudomonas syringae genetics
Pseudomonas syringae pathogenicity
Sequence Homology, Amino Acid
Structure-Activity Relationship
Two-Hybrid System Techniques
Virulence genetics
Bacterial Proteins metabolism
Plant Diseases microbiology
Plant Proteins metabolism
Protein Serine-Threonine Kinases metabolism
Pseudomonas syringae metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0960-7412
- Volume :
- 52
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- The Plant journal : for cell and molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 17764515
- Full Text :
- https://doi.org/10.1111/j.1365-313X.2007.03259.x