title: Pseudomonas syringae pv. tomato DC3000 Type III Secretion Effector Polymutants Reveal an Interplay between HopAD1 and AvrPtoB.
abstract: The bacterial pathogen Pseudomonas syringae pv. tomato DC3000 suppresses the two-tiered plant innate immune system by injecting a complex repertoire of type III secretion effector (T3E) proteins. Beyond redundancy and interplay, individual T3Es may interact with multiple immunity-associated proteins, rendering their analysis challenging. We constructed a Pst DC3000 polymutant lacking all 36 T3Es and restored individual T3Es or their mutants to explore the interplay among T3Es. The weakly expressed T3E HopAD1 was sufficient to elicit immunity-associated cell death in Nicotiana benthamiana. HopAD1-induced cell death was suppressed partially by native AvrPtoB and completely by AvrPtoBM3, which has mutations disrupting its E3 ubiquitin ligase domain and two known domains for interacting with immunity-associated kinases. AvrPtoBM3 also gained the ability to interact with the immunity-kinase MKK2, which is required for HopAD1-dependent cell death. Thus, AvrPtoB has alternative, competing mechanisms for suppressing effector-triggered plant immunity. This approach allows the deconvolution of individual T3E activities.
authors.affiliation: School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Hai-Lei
authors.initials: HL
authors.lastname: Wei
authors.affiliation: School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Suma
authors.initials: S
authors.lastname: Chakravarthy
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Mathieu
authors.affiliation: School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Tyler C
authors.initials: TC
authors.lastname: Helmann
authors.affiliation: United States Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Stodghill
authors.affiliation: School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA; United States Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Swingle
authors.affiliation: School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA; Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA. Electronic address: gbm7@cornell.edu.
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Martin
authors.affiliation: School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA. Electronic address: arc2@cornell.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Collmer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death; D015964:Gene Expression Regulation, Bacterial; D054884:Host-Pathogen Interactions; D048370:MAP Kinase Kinase 2 / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D057865:Plant Immunity; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D044224:Pseudomonas syringae / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology / Q000382:microbiology; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; C081695:avrPto protein, Pseudomonas syringae; D044767:Ubiquitin-Protein Ligases; C084354:Pto protein, Lycopersicon; D017346:Protein Serine-Threonine Kinases; D048370:MAP Kinase Kinase 2