title: The effector AWR5 from the plant pathogen Ralstonia solanacearum is an inhibitor of the TOR signalling pathway.
abstract: Bacterial pathogens possess complex type III effector (T3E) repertoires that are translocated inside the host cells to cause disease. However, only a minor proportion of these effectors have been assigned a function. Here, we show that the T3E AWR5 from the phytopathogen Ralstonia solanacearum is an inhibitor of TOR, a central regulator in eukaryotes that controls the switch between cell growth and stress responses in response to nutrient availability. Heterologous expression of AWR5 in yeast caused growth inhibition and autophagy induction coupled to massive transcriptomic changes, unmistakably reminiscent of TOR inhibition by rapamycin or nitrogen starvation. Detailed genetic analysis of these phenotypes in yeast, including suppression of AWR5-induced toxicity by mutation of CDC55 and TPD3, encoding regulatory subunits of the PP2A phosphatase, indicated that AWR5 might exert its function by directly or indirectly inhibiting the TOR pathway upstream PP2A. We present evidence in planta that this T3E caused a decrease in TOR-regulated plant nitrate reductase activity and also that normal levels of TOR and the Cdc55 homologues in plants are required for R. solanacearum virulence. Our results suggest that the TOR pathway is a bona fide T3E target and further prove that yeast is a useful platform for T3E function characterisation.
authors.affiliation: Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain.|Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Crina
authors.initials: C
authors.lastname: Popa
authors.affiliation: Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.affiliation: Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Gil
authors.affiliation: Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Catalonia, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Tatjer
authors.affiliation: Laboratory of Applied Molecular and Cell Biology, Kagawa University, Kagawa, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Hashii
authors.affiliation: Laboratory of Applied Molecular and Cell Biology, Kagawa University, Kagawa, Japan.
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Tabuchi
authors.affiliation: Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain.
authors.forename: Núria S
authors.initials: NS
authors.lastname: Coll
authors.affiliation: Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Catalonia, Spain.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Ariño
authors.affiliation: Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain.|Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Valls
mesh_terms: D001343:Autophagy; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D054884:Host-Pathogen Interactions; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D043368:Ralstonia solanacearum / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000502:physiology*; D014026:Nicotiana / Q000382:microbiology; D059467:Transcriptome
chemical_list: D001426:Bacterial Proteins; D010940:Plant Proteins; D047428:Protein Kinase Inhibitors; D029701:Saccharomyces cerevisiae Proteins; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus