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Updated: Aug 9, 2026
10:07
Identification of Post-translational Modifications of Plant Protein Complexes
Published on: February 22, 2014
Pseudomonas syringae Hrp type III secretion system and effector proteins
A Collmer1, J L Badel, A O Charkowski
1Department of Plant Pathology, Cornell University, Ithaca, NY 14853-4203, USA. arc2@cornell.edu
Summary
Pseudomonas syringae uses a type III secretion system to inject effector proteins into host cells. This system
Area of Science:
- Microbiology
- Plant Pathology
- Bacterial Pathogenesis
Background:
- Pseudomonas syringae utilizes a type III secretion system (T3SS) to deliver virulence effector proteins into host cells, impacting both plants and animals.
- The hrp/hrc genes encode the T3SS in P. syringae, while avr and hop genes encode the effector proteins.
Purpose of the Study:
- To investigate the structure and function of the Hrp pathogenicity island (Pai) in P. syringae.
- To determine the role of conserved and exchangeable effector loci in P. syringae pathogenicity.
- To explore the universality of effector protein secretion mechanisms across different bacterial pathogens.
Main Methods:
- Analysis of hrp/hrc gene organization in P. syringae strains.
- Functional characterization of the Hrp pathogenicity island using cosmid complementation.
- Investigating effector protein secretion in culture under various conditions.
- Genetic manipulation of P. syringae strains to assess pathogenicity.
Main Results:
- The Hrp pathogenicity island in P. syringae is a tripartite mosaic structure.
- A portion of the Hrp pathogenicity island from P. syringae strain 61 can confer effector injection and hypersensitive response in heterologous bacteria.
- The conserved effector locus is crucial for pathogenicity, while the exchangeable locus has a minor role.
- The type III secretion systems of plant and animal pathogens recognize a universal targeting signal.
Conclusions:
- The Hrp pathogenicity island is a key virulence determinant in P. syringae.
- Type III secretion systems share conserved mechanisms for effector protein targeting and secretion.
- Understanding these mechanisms can inform strategies against bacterial pathogens.
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