ABSTRACT
Cloning of plant disease resistance genes is now commonplace in model plants. Recent attention has turned to how the proteins that they encode function biochemically to recognize their cognate Avirulence protein and to initiate the disease-resistance response. In addition, attention has turned to how the Avirulence proteins of pathogens might alter susceptible hosts for the benefit of the pathogen, and what plant proteins might be required for that process.
Subject(s)
Bacterial Proteins/genetics , Genes, Plant , Immunity, Innate/genetics , Plant Diseases/genetics , Plant Proteins/genetics , Genes, Bacterial/immunology , Genes, Plant/immunology , Translocation, Genetic , Viral Proteins/genetics , Virulence/geneticsABSTRACT
Bacterial pathogens of plants and animals utilize conserved type III delivery systems to traffic effector proteins into host cells. Plant innate immune systems evolved disease resistance (R) genes to recognize some type III effectors, termed avirulence (Avr) proteins. On disease-susceptible (r) plants, Avr proteins can contribute to pathogen virulence. We demonstrate that several type III effectors from Pseudomonas syringae are targeted to the host plasma membrane and that efficient membrane association enhances function. Efficient localization of three Avr proteins requires consensus myristoylation sites, and Avr proteins can be myristoylated inside the host cell. These prokaryotic type III effectors thus utilize a eukaryote-specific posttranslational modification to access the subcellular compartment where they function.
Subject(s)
Bacterial Proteins/metabolism , Pseudomonas/metabolism , Acylation , Animals , Biological Transport , Cell Membrane/metabolism , Pseudomonas/pathogenicity , Pseudomonas/ultrastructure , VirulenceABSTRACT
Phytopathogenic bacteria deliver effectors of disease into plant hosts via a Type III secretion system. These Type III effectors have genetically determined roles in virulence. They also are among the components recognized by the putative receptors of the plant innate immune system. Recent breakthroughs include localization of some of these Type III effectors to specific host cell compartments, and the first dissection of pathogenicity islands that carry them.
