title: BTB-BACK Domain Protein POB1 Suppresses Immune Cell Death by Targeting Ubiquitin E3 ligase PUB17 for Degradation.
abstract: Hypersensitive response programmed cell death (HR-PCD) is a critical feature in plant immunity required for pathogen restriction and prevention of disease development. The precise control of this process is paramount to cell survival and an effective immune response. The discovery of new components that function to suppress HR-PCD will be instrumental in understanding the regulation of this fundamental mechanism. Here we report the identification and characterisation of a BTB domain E3 ligase protein, POB1, that functions to suppress HR-PCD triggered by evolutionarily diverse pathogens. Nicotiana benthamiana and tobacco plants with reduced POB1 activity show accelerated HR-PCD whilst those with increased POB1 levels show attenuated HR-PCD. We demonstrate that POB1 dimerization and nuclear localization are vital for its function in HR-PCD suppression. Using protein-protein interaction assays, we identify the Plant U-Box E3 ligase PUB17, a well established positive regulator of plant innate immunity, as a target for POB1-mediated proteasomal degradation. Using confocal imaging and in planta immunoprecipitation assays we show that POB1 interacts with PUB17 in the nucleus and stimulates its degradation. Mutated versions of POB1 that show reduced interaction with PUB17 fail to suppress HR-PCD, indicating that POB1-mediated degradation of PUB17 U-box E3 ligase is an important step for negative regulation of specific immune pathways in plants. Our data reveals a new mechanism for BTB domain proteins in suppressing HR-PCD in plant innate immune responses.
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, United Kingdom.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Orosa
authors.affiliation: Division of Plant Sciences, University of Dundee (at JHI), Invergowrie, Dundee, United Kingdom.|Key Laboratory of Horticultural Plant Biology (HAU), Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: He
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, United Kingdom.
authors.forename: Joelle
authors.initials: J
authors.lastname: Mesmar
authors.affiliation: Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee, United Kingdom.
authors.forename: Eleanor M
authors.identifier: 0000-0002-5301-4268
authors.initials: EM
authors.lastname: Gilroy
authors.affiliation: Division of Plant Sciences, University of Dundee (at JHI), Invergowrie, Dundee, United Kingdom.
authors.forename: Hazel
authors.initials: H
authors.lastname: McLellan
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, United Kingdom.
authors.forename: Chengwei
authors.initials: C
authors.lastname: Yang
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, United Kingdom.
authors.forename: Adam
authors.initials: A
authors.lastname: Craig
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, United Kingdom.
authors.forename: Mark
authors.identifier: 0000-0003-1843-9348
authors.initials: M
authors.lastname: Bailey
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, United Kingdom.
authors.forename: Cunjin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Warwick Systems Biology Centre, University of Warwick, United Kingdom.
authors.forename: Jonathan David
authors.initials: JD
authors.lastname: Moore
authors.affiliation: Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee, United Kingdom.
authors.forename: Petra C
authors.identifier: 0000-0002-7021-9097
authors.initials: PC
authors.lastname: Boevink
authors.affiliation: Key Laboratory of Horticultural Plant Biology (HAU), Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Zhendong
authors.initials: Z
authors.lastname: Tian
authors.affiliation: Division of Plant Sciences, University of Dundee (at JHI), Invergowrie, Dundee, United Kingdom.|Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee, United Kingdom.
authors.forename: Paul R J
authors.initials: PR
authors.lastname: Birch
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, United Kingdom.
authors.forename: Ari
authors.initials: A
authors.lastname: Sadanandom
mesh_terms: D016923:Cell Death; D009154:Mutation; D057865:Plant Immunity; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D059748:Proteolysis; D014026:Nicotiana / Q000235:genetics / Q000276:immunology; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D044767:Ubiquitin-Protein Ligases