Screen of non-annotated small secreted proteins of Pseudomonas syringae reveals a virulence factor that inhibits tomato immune proteases
Author(s)
Type
Journal Article
Abstract
Pseudomonas syringae pv. tomato DC3000 (PtoDC3000) is an extracellular model plant pathogen, yet its potential to produce secreted effectors that manipulate the apoplast has been under investigated. Here we identified 131 candidate small, secreted, non-annotated proteins from the PtoDC3000 genome, most of which are common to Pseudomonas species and potentially expressed during apoplastic colonization. We produced 43 of these proteins through a custom-made gateway-compatible expression system for extracellular bacterial proteins, and screened them for their ability to inhibit the secreted immune protease C14 of tomato using competitive activity-based protein profiling. This screen revealed C14-inhibiting protein-1 (Cip1), which contains motifs of the chagasin-like protease inhibitors. Cip1 mutants are less virulent on tomato, demonstrating the importance of this effector in apoplastic immunity. Cip1 also inhibits immune protease Pip1, which is known to suppress PtoDC3000 infection, but has a lower affinity for its close homolog Rcr3, explaining why this protein is not recognized in tomato plants carrying the Cf-2 resistance gene, which uses Rcr3 as a co-receptor to detect pathogen-derived protease inhibitors. Thus, this approach uncovered a protease inhibitor of P. syringae, indicating that also P. syringae secretes effectors that selectively target apoplastic host proteases of tomato, similar to tomato pathogenic fungi, oomycetes and nematodes.
Date Issued
2016-09
Date Acceptance
2016-08-15
Citation
PLoS Pathogens, 2016, 12 (9)
ISSN
1553-7366
Publisher
Public Library of Science (PLoS)
Journal / Book Title
PLoS Pathogens
Volume
12
Issue
9
Copyright Statement
Copyright: © 2016 Shindo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/27603016
Subjects
Bacterial Proteins
Peptide Hydrolases
Plant Diseases
Plant Leaves
Plant Proteins
Protease Inhibitors
Pseudomonas syringae
Solanum lycopersicum
Virulence
Virulence Factors
Publication Status
Published
Coverage Spatial
United States
Article Number
e1005874
Date Publish Online
2016-09-07