title: Direct and Indirect Targeting of PP2A by Conserved Bacterial Type-III Effector Proteins.
abstract: Bacterial AvrE-family Type-III effector proteins (T3Es) contribute significantly to the virulence of plant-pathogenic species of Pseudomonas, Pantoea, Ralstonia, Erwinia, Dickeya and Pectobacterium, with hosts ranging from monocots to dicots. However, the mode of action of AvrE-family T3Es remains enigmatic, due in large part to their toxicity when expressed in plant or yeast cells. To search for targets of WtsE, an AvrE-family T3E from the maize pathogen Pantoea stewartii subsp. stewartii, we employed a yeast-two-hybrid screen with non-lethal fragments of WtsE and a synthetic genetic array with full-length WtsE. Together these screens indicate that WtsE targets maize protein phosphatase 2A (PP2A) heterotrimeric enzyme complexes via direct interaction with B' regulatory subunits. AvrE1, another AvrE-family T3E from Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), associates with specific PP2A B' subunit proteins from its susceptible host Arabidopsis that are homologous to the maize B' subunits shown to interact with WtsE. Additionally, AvrE1 was observed to associate with the WtsE-interacting maize proteins, indicating that PP2A B' subunits are likely conserved targets of AvrE-family T3Es. Notably, the ability of AvrE1 to promote bacterial growth and/or suppress callose deposition was compromised in Arabidopsis plants with mutations of PP2A genes. Also, chemical inhibition of PP2A activity blocked the virulence activity of both WtsE and AvrE1 in planta. The function of HopM1, a Pto DC3000 T3E that is functionally redundant to AvrE1, was also impaired in specific PP2A mutant lines, although no direct interaction with B' subunits was observed. These results indicate that sub-component specific PP2A complexes are targeted by bacterial T3Es, including direct targeting by members of the widely conserved AvrE-family.
authors.affiliation: Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Lin
authors.initials: L
authors.lastname: Jin
authors.affiliation: Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America.|Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America.|Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America.
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Ham
authors.affiliation: Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Hage
authors.affiliation: Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Wanying
authors.initials: W
authors.lastname: Zhao
authors.affiliation: Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Jaricelis
authors.initials: J
authors.lastname: Soto-Hernández
authors.affiliation: Division of Applied Life Science (BK21Plus), PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea.
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.affiliation: College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea.
authors.forename: Seung-Mann
authors.initials: SM
authors.lastname: Paek
authors.affiliation: College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea.
authors.forename: Min Gab
authors.initials: MG
authors.lastname: Kim
authors.affiliation: Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Boone
authors.affiliation: Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: David L
authors.initials: DL
authors.lastname: Coplin
authors.affiliation: Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America.|Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Mackey
mesh_terms: D017360:Arabidopsis / Q000382:microbiology; D001426:Bacterial Proteins / Q000378:metabolism*; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000378:metabolism*; D047468:Immunoprecipitation; D018551:Solanum lycopersicum / Q000382:microbiology; D020636:Pantoea / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014026:Nicotiana / Q000382:microbiology; D020798:Two-Hybrid System Techniques; D000069296:Type III Secretion Systems; D014774:Virulence / Q000502:physiology*; D003313:Zea mays / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D000069296:Type III Secretion Systems; D054648:Protein Phosphatase 2