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Herold L, Choi S, He SY, Zipfel C. The conserved AvrE family of bacterial effectors: functions and targets during pathogenesis. Trends Microbiol 2024:S0966-842X(24)00222-1. [PMID: 39278787 DOI: 10.1016/j.tim.2024.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/22/2024] [Accepted: 08/22/2024] [Indexed: 09/18/2024]
Abstract
The AvrE family of type III secreted effectors are highly conserved among many agriculturally important phytopathogenic bacteria. Despite their critical roles in the pathogenesis of phytopathogenic bacteria, the molecular functions and virulence mechanisms of these effectors have been largely unknown. However, recent studies have identified host-interacting proteins and demonstrated that AvrE family effectors can form water-permeable channels in the plant plasma membrane (PM) to create a hydrated and nutrient-rich extracellular space (apoplast) required for disease establishment. Here, we summarize these recent discoveries and highlight open questions related to AvrE-targeted host proteins.
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Affiliation(s)
- Laura Herold
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Sera Choi
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC, USA; Howard Hughes Medical Institute, Duke University, Durham, NC, USA
| | - Cyril Zipfel
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland; The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, UK.
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2
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Nomura K, Andreazza F, Cheng J, Dong K, Zhou P, He SY. Bacterial pathogens deliver water- and solute-permeable channels to plant cells. Nature 2023; 621:586-591. [PMID: 37704725 PMCID: PMC10511319 DOI: 10.1038/s41586-023-06531-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 08/10/2023] [Indexed: 09/15/2023]
Abstract
Many animal- and plant-pathogenic bacteria use a type III secretion system to deliver effector proteins into host cells1,2. Elucidation of how these effector proteins function in host cells is critical for understanding infectious diseases in animals and plants3-5. The widely conserved AvrE-family effectors, including DspE in Erwinia amylovora and AvrE in Pseudomonas syringae, have a central role in the pathogenesis of diverse phytopathogenic bacteria6. These conserved effectors are involved in the induction of 'water soaking' and host cell death that are conducive to bacterial multiplication in infected tissues. However, the exact biochemical functions of AvrE-family effectors have been recalcitrant to mechanistic understanding for three decades. Here we show that AvrE-family effectors fold into a β-barrel structure that resembles bacterial porins. Expression of AvrE and DspE in Xenopus oocytes results in inward and outward currents, permeability to water and osmolarity-dependent oocyte swelling and bursting. Liposome reconstitution confirmed that the DspE channel alone is sufficient to allow the passage of small molecules such as fluorescein dye. Targeted screening of chemical blockers based on the predicted pore size (15-20 Å) of the DspE channel identified polyamidoamine dendrimers as inhibitors of the DspE/AvrE channels. Notably, polyamidoamines broadly inhibit AvrE and DspE virulence activities in Xenopus oocytes and during E. amylovora and P. syringae infections. Thus, we have unravelled the biochemical function of a centrally important family of bacterial effectors with broad conceptual and practical implications in the study of bacterial pathogenesis.
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Affiliation(s)
- Kinya Nomura
- Department of Biology, Duke University, Durham, NC, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC, USA
| | | | - Jie Cheng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Ke Dong
- Department of Biology, Duke University, Durham, NC, USA.
| | - Pei Zhou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC, USA.
- Howard Hughes Medical Institute, Duke University, Durham, NC, USA.
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3
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Nomura K, Andreazza F, Cheng J, Dong K, Zhou P, He SY. Bacterial pathogens deliver water/solute-permeable channels as a virulence strategy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.29.547699. [PMID: 37546725 PMCID: PMC10402153 DOI: 10.1101/2023.07.29.547699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Many animal and plant pathogenic bacteria utilize a type III secretion system to deliver effector proteins into the host cell 1,2 . Elucidation of how these effector proteins function in the host cell is critical for understanding infectious diseases in animals and plants 3-5 . The widely conserved AvrE/DspE-family effectors play a central role in the pathogenesis of diverse phytopathogenic bacteria 6 . These conserved effectors are involved in the induction of "water-soaking" and host cell death that are conducive to bacterial multiplication in infected tissues. However, the exact biochemical functions of AvrE/DspE-family effectors have been recalcitrant to mechanistic understanding for three decades. Here we show that AvrE/DspE-family effectors fold into a β-barrel structure that resembles bacterial porins. Expression of AvrE and DspE in Xenopus oocytes results in (i) inward and outward currents, (ii) permeability to water and (iii) osmolarity-dependent oocyte swelling and bursting. Liposome reconstitution confirmed that the DspE channel alone is sufficient to allow the passage of small molecules such as fluorescein dye. Targeted screening of chemical blockers based on the predicted pore size (15-20 Å) of the DspE channel identified polyamidoamine (PAMAM) dendrimers as inhibitors of the DspE/AvrE channels. Remarkably, PAMAMs broadly inhibit AvrE/DspE virulence activities in Xenopus oocytes and during Erwinia amylovora and Pseudomonas syringae infections. Thus, we have unraveled the enigmatic function of a centrally important family of bacterial effectors with significant conceptual and practical implications in the study of bacterial pathogenesis.
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Affiliation(s)
- Kinya Nomura
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
| | | | - Jie Cheng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ke Dong
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Pei Zhou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
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4
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Zhao M, Shin GY, Stice S, Bown JL, Coutinho T, Metcalf WW, Gitaitis R, Kvitko B, Dutta B. A Novel Biosynthetic Gene Cluster Across the Pantoea Species Complex Is Important for Pathogenicity in Onion. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2023; 36:176-188. [PMID: 36534063 PMCID: PMC10433531 DOI: 10.1094/mpmi-08-22-0165-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Onion center rot is caused by at least four species of genus Pantoea (P. ananatis, P. agglomerans, P. allii, and P. stewartii subsp. indologenes). Critical onion pathogenicity determinants for P. ananatis were recently described, but whether those determinants are common among other onion-pathogenic Pantoea species remains unknown. In this work, we report onion pathogenicity determinants in P. stewartii subsp. indologenes and P. allii. We identified two distinct secondary metabolite biosynthetic gene clusters present separately in different strains of onion-pathogenic P. stewartii subsp. indologenes. One cluster is similar to the previously described HiVir phosphonate biosynthetic cluster identified in P. ananatis and another is a novel putative phosphonate biosynthetic gene cluster, which we named Halophos. The Halophos gene cluster was also identified in P. allii strains. Both clusters are predicted to be phosphonate biosynthetic clusters based on the presence of a characteristic phosphoenolpyruvate phosphomutase (pepM) gene. The deletion of the pepM gene from either HiVir or Halophos clusters in P. stewartii subsp. indologenes caused loss of necrosis on onion leaves and red onion scales and resulted in significantly lower bacterial populations compared with the corresponding wild-type and complemented strains. Seven (halB to halH) of 11 genes (halA to halK) in the Halophos gene cluster are required for onion necrosis phenotypes. The onion nonpathogenic strain PNA15-2 (P. stewartii subsp. indologenes) gained the capacity to cause foliar necrosis on onion via exogenous expression of a minimal seven-gene Halophos cluster (genes halB to halH). Furthermore, cell-free culture filtrates of PNA14-12 expressing the intact Halophos gene cluster caused necrosis on onion leaves consistent with the presence of a secreted toxin. Based on the similarity of proteins to those with experimentally determined functions, we are able to predict most of the steps in Halophos biosynthesis. Together, these observations indicate that production of the toxin phosphonate seems sufficient to account for virulence of a variety of different Pantoea strains, although strains differ in possessing a single but distinct phosphonate biosynthetic cluster. Overall, this is the first report of onion pathogenicity determinants in P. stewartii subsp. indologenes and P. allii. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Mei Zhao
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, P. R. China
- Department of Plant Pathology, University of Georgia, Tifton GA USA
| | - Gi Yoon Shin
- Department of Plant Pathology, University of Georgia, Athens GA USA
| | - Shaun Stice
- Department of Plant Pathology, University of Georgia, Athens GA USA
| | - Jonathon Luke Bown
- Department of Microbiology, University of Illinois, Urbana-Champaign, IL
| | - Teresa Coutinho
- The Genomics Research Institute, University of Pretoria, Hatfield, South Africa
| | - William W. Metcalf
- Department of Microbiology, University of Illinois, Urbana-Champaign, IL
| | - Ron Gitaitis
- Department of Plant Pathology, University of Georgia, Tifton GA USA
| | - Brian Kvitko
- Department of Plant Pathology, University of Georgia, Athens GA USA
| | - Bhabesh Dutta
- Department of Plant Pathology, University of Georgia, Tifton GA USA
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Olawole OI, Gleason ML, Beattie GA. Expression and Functional Analysis of the Type III Secretion System Effector Repertoire of the Xylem Pathogen Erwinia tracheiphila on Cucurbits. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:768-778. [PMID: 35471035 DOI: 10.1094/mpmi-01-22-0002-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The predicted repertoire of type III secretion system effectors (T3SEs) in Erwinia tracheiphila, causal agent of cucurbit bacterial wilt, is much larger than in xylem pathogens in the closely related genera Erwinia and Pantoea. The genomes of strains BHKY and SCR3, which represent distinct E. tracheiphila clades, encode at least 6 clade-specific and 12 shared T3SEs. The strains expressed the majority of the T3SE genes examined in planta. Among the shared T3SE genes, eop1 was expressed most highly in both strains in squash (Cucurbita pepo) and muskmelon (Cucumis melo) but the clade-specific gene avrRpm2 was expressed 40- to 900-fold more than eop1 in BHKY. The T3SEs AvrRpm2, Eop1, SrfC, and DspE contributed to BHKY virulence on squash and muskmelon, as shown using combinatorial mutants involving six T3SEs, whereas OspG and AvrB4 contributed to BHKY virulence only on muskmelon, demonstrating host-specific virulence functions. Moreover, Eop1 was functionally redundant with AvrRpm2, SrfC, OspG, and AvrB4 in BHKY, and BHKY mutants lacking up to five effector genes showed similar virulence to mutants lacking only two genes. The T3SEs OspG, AvrB4, and DspE contributed additively to SCR3 virulence on muskmelon and were not functionally redundant with Eop1. Rather, loss of eop1 and avrB4 restored wild-type virulence to the avrB4 mutant, suggesting that Eop1 suppresses a functionally redundant effector in SCR3. These results highlight functional differences in effector inventories between two E. tracheiphila clades, provide the first evidence of OspG as a phytopathogen effector, and suggest that Eop1 may be a metaeffector influencing virulence. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Olakunle I Olawole
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011-1101, U.S.A
| | - Mark L Gleason
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011-1101, U.S.A
| | - Gwyn A Beattie
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011-1101, U.S.A
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Hu Y, Ding Y, Cai B, Qin X, Wu J, Yuan M, Wan S, Zhao Y, Xin XF. Bacterial effectors manipulate plant abscisic acid signaling for creation of an aqueous apoplast. Cell Host Microbe 2022; 30:518-529.e6. [PMID: 35247331 DOI: 10.1016/j.chom.2022.02.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/05/2021] [Accepted: 02/02/2022] [Indexed: 01/23/2023]
Abstract
Phytopathogens like Pseudomonas syringae induce "water soaking" in the apoplastic space of plant leaf tissue as a key virulence mechanism. Water soaking is commonly observed in diverse pathosystems, yet the underlying physiological basis remains largely elusive. Here, we show that one of the strong P. syringae water-soaking inducers, AvrE, alters the regulation of abscisic acid (ABA) to induce ABA signaling, stomatal closure, and, thus, water soaking. AvrE binds and inhibits the function of Arabidopsis type one protein phosphatases (TOPPs), which negatively regulate ABA by suppressing SnRK2s, a key node of the ABA signaling pathway. The topp12537 quintuple mutants display significantly enhanced water soaking after P. syringae inoculation, whereas the loss of the ABA pathway dampens P. syringae-induced water soaking and disease. Our study uncovers the hijacking of ABA signaling and stomatal closure by P. syringae effectors as key mechanisms of disease susceptibility.
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Affiliation(s)
- Yezhou Hu
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Yanxia Ding
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Boying Cai
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaohui Qin
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jingni Wu
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Minhang Yuan
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Shiwei Wan
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yang Zhao
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Xiu-Fang Xin
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China; Chinese Academy of Sciences (CAS) and John Innes Centre, Centre of Excellence for Plant and Microbial Sciences, Shanghai 200032, China.
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7
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Dynamic nutrient acquisition from a hydrated apoplast supports biotrophic proliferation of a bacterial pathogen of maize. Cell Host Microbe 2022; 30:502-517.e4. [PMID: 35421350 DOI: 10.1016/j.chom.2022.03.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 02/09/2022] [Accepted: 03/10/2022] [Indexed: 11/24/2022]
Abstract
Plant pathogens perturb their hosts to create environments suitable for their proliferation, including the suppression of immunity and promotion of water and nutrient availability. Although necrotrophs obtain water and nutrients by disrupting host-cell integrity, it is unknown whether hemibiotrophs, such as the bacterial pathogen Pantoea stewartii subsp. stewartii (Pnss), actively liberate water and nutrients during the early, biotrophic phase of infection. Here, we show that water and metabolite accumulation in the apoplast of Pnss-infected maize leaves precedes the disruption of host-cell integrity. Nutrient acquisition during this biotrophic phase is a dynamic process; the partitioning of metabolites into the apoplast rate limiting for their assimilation by proliferating Pnss cells. The formation of a hydrated and nutritive apoplast is driven by an AvrE-family type III effector, WtsE. Given the broad distribution of AvrE-family effectors, this work highlights the importance of actively acquiring water and nutrients for the proliferation of phytopathogenic bacteria during biotrophy.
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Bauters L, Stojilković B, Gheysen G. Pathogens pulling the strings: Effectors manipulating salicylic acid and phenylpropanoid biosynthesis in plants. MOLECULAR PLANT PATHOLOGY 2021; 22:1436-1448. [PMID: 34414650 PMCID: PMC8518561 DOI: 10.1111/mpp.13123] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/15/2021] [Accepted: 08/01/2021] [Indexed: 06/01/2023]
Abstract
During evolution, plants have developed sophisticated ways to cope with different biotic and abiotic stresses. Phytohormones and secondary metabolites are known to play pivotal roles in defence responses against invading pathogens. One of the key hormones involved in plant immunity is salicylic acid (SA), of which the role in plant defence is well established and documented. Plants produce an array of secondary metabolites categorized in different classes, with the phenylpropanoids as major players in plant immunity. Both SA and phenylpropanoids are needed for an effective immune response by the plant. To successfully infect the host, pathogens secrete proteins, called effectors, into the plant tissue to lower defence. Secreted effectors can interfere with several metabolic or signalling pathways in the host to facilitate infection. In this review, we will focus on the different strategies pathogens have developed to affect the levels of SA and phenylpropanoids to increase plant susceptibility.
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Affiliation(s)
- Lander Bauters
- Department of BiotechnologyFaculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Boris Stojilković
- Department of BiotechnologyFaculty of Bioscience EngineeringGhent UniversityGhentBelgium
| | - Godelieve Gheysen
- Department of BiotechnologyFaculty of Bioscience EngineeringGhent UniversityGhentBelgium
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Huong DDT, Rajalingam N, Lee YH. Characterization of Virulence Function of Pseudomonas cichorii Avirulence Protein E1 (AvrE1) during Host Plant Infection. THE PLANT PATHOLOGY JOURNAL 2021; 37:494-501. [PMID: 34847636 PMCID: PMC8632607 DOI: 10.5423/ppj.nt.07.2021.0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/17/2021] [Accepted: 08/29/2021] [Indexed: 06/13/2023]
Abstract
Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However, the function of these effectors, including avirulence protein E1 (AvrE1), in the pathogenicity of P. cichorii, remains unexplored. In this study, to investigate the function of avrE1 in P. cichorii JBC1 (PcJBC1), we created an avrE1-deficient mutant (JBC1ΔavrE1) using CRISPR/Cas9. The disease severity caused by JBC1ΔavrE1 in tomato plants significantly decreased by reducing water soaking during early infection stage, as evidenced by the electrolyte leakage in infected leaves. The disease symptoms caused by JBC1ΔavrE1 in the cabbage midrib were light-brown spots compared to the dark-colored ones caused by PcJBC1, which indicates the role of AvrE1 in cell lysis. The avrE1-deficient mutant failed to elicit cell death in non-host tobacco plants. Disease severity and cell death caused by JBC1ΔavrE1 in host and non-host plants were restored through heterologous complementation with avrE1 from Pseudomonas syringae pv. tomato DC3000 (PstDC3000). Overall, our results indicate that avrE1 contributes to cell death during early infection, which consequently increases disease development in host plants. The roles of PcJBC1 AvrE1 in host cells remain to be elucidated.
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Affiliation(s)
| | | | - Yong Hoon Lee
- Division of Biotechnology, Jeonbuk National University, Iksan 54596, Korea
- Advanced Institute of Environment and Bioscience, Plant Medical Research Center, and Institute of Bio-industry, Jeonbuk National University, Iksan 54596, Korea
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10
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Yuan X, Hulin MT, Sundin GW. Effectors, chaperones, and harpins of the Type III secretion system in the fire blight pathogen Erwinia amylovora: a review. JOURNAL OF PLANT PATHOLOGY 2021; 103:25-39. [PMID: 0 DOI: 10.1007/s42161-020-00623-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/23/2020] [Indexed: 05/20/2023]
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11
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Debler JW, Henares BM, Lee RC. Agroinfiltration for transient gene expression and characterisation of fungal pathogen effectors in cool-season grain legume hosts. PLANT CELL REPORTS 2021; 40:805-818. [PMID: 33811500 PMCID: PMC8058004 DOI: 10.1007/s00299-021-02671-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 01/30/2021] [Indexed: 05/05/2023]
Abstract
KEY MESSAGE Modified pEAQ-HT-DEST1 vectors were used for agroinfiltration in legumes. We demonstrate protein expression and export in pea, lentil, and faba bean; however, the method for chickpea was not successful. Agroinfiltration is a valuable research method for investigating virulence and avirulence effector proteins from pathogens and pests, where heterologous effector proteins are transiently expressed in plant leaves and hypersensitive necrosis responses and other effector functions can be assessed. Nicotiana benthamiana is widely used for agroinfiltration and the characterisation of broad-spectrum effectors. The method has also been used in other plant species including field pea, but not yet developed for chickpea, lentil, or faba bean. Here, we have modified the pEAQ-HT-DEST1 vector for expression of 6 × histidine-tagged green-fluorescent protein (GFP) and the known necrosis-inducing broad-spectrum effector necrosis and ethylene-inducing peptide (Nep1)-like protein (NLP). Modified pEAQ-based vectors were adapted to encode signal peptide sequences for apoplast targeting of expressed proteins. We used confocal microscopy to assess the level of GFP expression in agroinfiltrated leaves. While at 3 days after infiltration in N. benthamiana, GFP was expressed at a relatively high level, expression in field pea and faba bean at the same time point was relatively low. In lentil, an expression level of GFP similar to field pea and faba bean at 3 days was only observed after 5 days. Chickpea leaf cells were transformed at low frequency and agroinfiltration was concluded to not be successful for chickpea. We concluded that the pEAQ vector is suitable for testing host-specific effectors in field pea, lentil, and faba bean, but low transformation efficiency limits the utility of the method for chickpea.
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Affiliation(s)
- Johannes W Debler
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, 1 Kent St, Bentley, WA, 6102, Australia
| | - Bernadette M Henares
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, 1 Kent St, Bentley, WA, 6102, Australia
| | - Robert C Lee
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, 1 Kent St, Bentley, WA, 6102, Australia.
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12
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Yang B, Wang Y, Tian M, Dai K, Zheng W, Liu Z, Yang S, Liu X, Shi D, Zhang H, Wang Y, Ye W, Wang Y. Fg12 ribonuclease secretion contributes to Fusarium graminearum virulence and induces plant cell death. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2021; 63:365-377. [PMID: 32725938 DOI: 10.1111/jipb.12997] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
Filamentous fungal pathogens secrete effectors that modulate host immunity and facilitate infection. Fusarium graminearum is an important plant pathogen responsible for various devastating diseases. However, little is known about the function of effector proteins secreted by F. graminearum. Herein, we identified several effector candidates in the F. graminearum secretome. Among them, the secreted ribonuclease Fg12 was highly upregulated during the early stages of F. graminearum infection in soybean; its deletion compromised the virulence of F. graminearum. Transient expression of Fg12 in Nicotiana benthamiana induced cell death in a light-dependent manner. Fg12 possessed ribonuclease (RNase) activity, degrading total RNA. The enzymatic activity of Fg12 was required for its cell death-promoting effects. Importantly, the ability of Fg12 to induce cell death was independent of BAK1/SOBIR1, and treatment of soybean with recombinant Fg12 protein induced resistance to various pathogens, including F. graminearum and Phytophthora sojae. Overall, our results provide evidence that RNase effectors not only contribute to pathogen virulence but also induce plant cell death.
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Affiliation(s)
- Bo Yang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuyin Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Mengjun Tian
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Kaixin Dai
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Wenyue Zheng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zehan Liu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Sen Yang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xinyu Liu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Dongya Shi
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Haifeng Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yan Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, 210095, China
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13
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Abidin N, Ismail SI, Vadamalai G, Yusof MT, Hakiman M, Karam DS, Ismail-Suhaimy NW, Ibrahim R, Zulperi D. Genetic diversity of Pantoea stewartii subspecies stewartii causing jackfruit-bronzing disease in Malaysia. PLoS One 2020; 15:e0234350. [PMID: 32530926 PMCID: PMC7292391 DOI: 10.1371/journal.pone.0234350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 05/23/2020] [Indexed: 12/12/2022] Open
Abstract
Jackfruit-bronzing is caused by bacteria Pantoea stewartii subspecies stewartii (P. stewartii subsp. stewartii), showing symptoms of yellowish-orange to reddish discolouration and rusty specks on pulps and rags of jackfruit. Twenty-eight pure bacterial strains were collected from four different jackfruit outbreak collection areas in Peninsular Malaysia (Jenderam, Maran, Muadzam Shah and Ipoh). Positive P. stewartii subsp. stewartii verification obtained in the study was based on the phenotypic, hypersensitivity, pathogenicity and molecular tests. Multilocus sequence analysis (MLSA) was performed using four housekeeping genes (gyrB, rpoB, atpD and infB) on all 28 bacterial strains. Single gyrB, rpoB, atpD and infB phylogenetic trees analyses revealed the bootstrap value of 99-100% between our bacterial strains with P. stewartii subsp. stewartii reference strains and P. stewartii subsp. indologenes reference strains. On the other hand, phylogenetic tree of the concatenated sequences of the four housekeeping genes revealed that our 28 bacterial strains were more closely related to P. stewartii subsp. stewartii (99% similarities) compared to its close relative P. stewartii subsp. indologenes, although sequence similarity between these two subspecies were up to 100%. All the strains collected from the four collection areas clustered together, pointing to no variation among the bacterial strains. This study improves our understanding and provided new insight on the genetic diversity of P. stewartii subsp. stewartii associated with jackfruit-bronzing in Malaysia.
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Affiliation(s)
- Nuraizat Abidin
- Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Siti Izera Ismail
- Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Ganesan Vadamalai
- Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Mohd Termizi Yusof
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Mansor Hakiman
- Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Daljit Singh Karam
- Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Noor Wahida Ismail-Suhaimy
- Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Rohaya Ibrahim
- Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Dzarifah Zulperi
- Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
- Laboratory of Sustainable Resources Management, Institute of Tropical Forestry and Forest Products, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
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14
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Doblas-Ibáñez P, Deng K, Vasquez MF, Giese L, Cobine PA, Kolkman JM, King H, Jamann TM, Balint-Kurti P, De La Fuente L, Nelson RJ, Mackey D, Smith LG. Dominant, Heritable Resistance to Stewart's Wilt in Maize Is Associated with an Enhanced Vascular Defense Response to Infection with Pantoea stewartii. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1581-1597. [PMID: 31657672 DOI: 10.1094/mpmi-05-19-0129-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Vascular wilt bacteria such as Pantoea stewartii, the causal agent of Stewart's bacterial wilt of maize (SW), are destructive pathogens that are difficult to control. These bacteria colonize the xylem, where they form biofilms that block sap flow leading to characteristic wilting symptoms. Heritable forms of SW resistance exist and are used in maize breeding programs but the underlying genes and mechanisms are mostly unknown. Here, we show that seedlings of maize inbred lines with pan1 mutations are highly resistant to SW. However, current evidence suggests that other genes introgressed along with pan1 are responsible for resistance. Genomic analyses of pan1 lines were used to identify candidate resistance genes. In-depth comparison of P. stewartii interaction with susceptible and resistant maize lines revealed an enhanced vascular defense response in pan1 lines characterized by accumulation of electron-dense materials in xylem conduits visible by electron microscopy. We propose that this vascular defense response restricts P. stewartii spread through the vasculature, reducing both systemic bacterial colonization of the xylem network and consequent wilting. Though apparently unrelated to the resistance phenotype of pan1 lines, we also demonstrate that the effector WtsE is essential for P. stewartii xylem dissemination, show evidence for a nutritional immunity response to P. stewartii that alters xylem sap composition, and present the first analysis of maize transcriptional responses to P. stewartii infection.
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Affiliation(s)
- Paula Doblas-Ibáñez
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Kaiyue Deng
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Miguel F Vasquez
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Laura Giese
- Department of Horticulture and Crop Sciences, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Paul A Cobine
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, U.S.A
| | - Judith M Kolkman
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
| | - Helen King
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Tiffany M Jamann
- Department of Crop Sciences, University of Illinois Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Peter Balint-Kurti
- United States Department of Agriculture-Agricultural Research Service, Plant Science Research Unit, Raleigh, NC 27695, U.S.A. and Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, U.S.A
| | | | - Rebecca J Nelson
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
| | - David Mackey
- Department of Horticulture and Crop Sciences, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Laurie G Smith
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
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15
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Deb D, Mackey D, Opiyo SO, McDowell JM. Application of alignment-free bioinformatics methods to identify an oomycete protein with structural and functional similarity to the bacterial AvrE effector protein. PLoS One 2018; 13:e0195559. [PMID: 29641586 PMCID: PMC5895030 DOI: 10.1371/journal.pone.0195559] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/23/2018] [Indexed: 11/23/2022] Open
Abstract
Diverse plant pathogens export effector proteins to reprogram host cells. One of the most challenging goals in the molecular plant-microbe field is to functionally characterize the complex repertoires of effectors secreted by these pathogens. For bacterial pathogens, the predominant class of effectors is delivered to host cells by Type III secretion. For oomycetes, the predominant class of effectors is defined by a signal peptide that mediates secretion from the oomycete and a conserved RxLR motif. Downy mildew pathogens and Phytophthora species maintain hundreds of candidate RxLR effector genes in their genomes. Although no primary sequence similarity is evident between bacterial Type III effectors (T3Es) and oomycete RXLR effectors, some bacterial and oomycete effectors have convergently evolved to target the same host proteins. Such effectors might have evolved domains that are functionally similar but sequence-unrelated. We reasoned that alignment-free bioinformatics approaches could be useful to identify structural similarities between bacterial and oomycete effectors. To test this approach, we used partial least squares regression, alignment-free bioinformatics methods to identify effector proteins from the genome of the oomycete Hyaloperonospora arabidopsidis that are similar to the well-studied AvrE1 effector from Pseudomonas syringae. This approach identified five RxLR proteins with putative structural similarity to AvrE1. We focused on one, HaRxL23, because it is an experimentally validated effector and it is conserved between distantly related oomycetes. Several experiments indicate that HaRxL23 is functionally similar to AvrE1, including the ability to partially rescue an AvrE1 loss-of-function mutant. This study provides an example of how an alignment-free bioinformatics approach can identify functionally similar effector proteins in the absence of primary sequence similarity. This approach could be useful to identify effectors that have convergently evolved regardless of whether the shared host target is known.
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Affiliation(s)
- Devdutta Deb
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, Virginia, United States of America
| | - David Mackey
- Departments of Horticulture and Crop Science and Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
| | - Stephen O. Opiyo
- Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center, Ohio State University, Columbus, Ohio, United States of America
- * E-mail: (SOO); (JMM)
| | - John M. McDowell
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, Virginia, United States of America
- * E-mail: (SOO); (JMM)
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16
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Duong DA, Stevens AM, Jensen RV. Complete Genome Assembly of Pantoea stewartii subsp. stewartii DC283, a Corn Pathogen. GENOME ANNOUNCEMENTS 2017; 5:e00435-17. [PMID: 28572317 PMCID: PMC5454200 DOI: 10.1128/genomea.00435-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 04/11/2017] [Indexed: 11/20/2022]
Abstract
The phytopathogen Pantoea stewartii subsp. stewartii DC283 causes Stewart's wilt disease in corn after transmission from the corn flea beetle insect vector. Here, we report that the complete annotated genome of P. stewartii DC283 has been fully assembled into one circular chromosome, 10 circular plasmids, and one linear phage.
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Affiliation(s)
- Duy An Duong
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Ann M Stevens
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Roderick V Jensen
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
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17
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Yang B, Wang Q, Jing M, Guo B, Wu J, Wang H, Wang Y, Lin L, Wang Y, Ye W, Dong S, Wang Y. Distinct regions of the Phytophthora essential effector Avh238 determine its function in cell death activation and plant immunity suppression. THE NEW PHYTOLOGIST 2017; 214:361-375. [PMID: 28134441 DOI: 10.1111/nph.14430] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 12/09/2016] [Indexed: 05/20/2023]
Abstract
Phytophthora pathogens secrete effectors to manipulate host innate immunity, thus facilitating infection. Among the RXLR effectors highly induced during Phytophthora sojae infection, Avh238 not only contributes to pathogen virulence but also triggers plant cell death. However, the detailed molecular basis of Avh238 functions remains largely unknown. We mapped the regions responsible for Avh238 functions in pathogen virulence and plant cell death induction using a strategy that combines investigation of natural variation and large-scale mutagenesis assays. The correlation between cellular localization and Avh238 functions was also evaluated. We found that the 79th residue (histidine or leucine) of Avh238 determined its cell death-inducing activity, and that the 53 amino acids in its C-terminal region are responsible for promoting Phytophthora infection. Transient expression of Avh238 in Nicotiana benthamiana revealed that nuclear localization is essential for triggering cell death, while Avh238-mediated suppression of INF1-triggered cell death requires cytoplasmic localization. Our results demonstrate that a representative example of an essential Phytophthora RXLR effector can evolve to escape recognition by the host by mutating one nucleotide site, and can also retain plant immunosuppressive activity to enhance pathogen virulence in planta.
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Affiliation(s)
- Bo Yang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Qunqing Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
- Department of Plant Pathology, Shandong Agricultural University, Taian, 271018, China
| | - Maofeng Jing
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Baodian Guo
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Jiawei Wu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Haonan Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Yang Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Long Lin
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Yan Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Suomeng Dong
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China
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18
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Measuring Callose Deposition, an Indicator of Cell Wall Reinforcement, During Bacterial Infection in Arabidopsis. Methods Mol Biol 2017; 1578:195-205. [PMID: 28220426 DOI: 10.1007/978-1-4939-6859-6_16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plant cell wall responds dynamically during interaction with various pathogens. Upon recognition of "nonself" components, plant cells deploy a variety of immune responses including cell wall fortification. Callose, a β-(1, 3)-D-glucan polymer, is a component of the material deposited at the site of infection between the plasma membrane and the preexisting cell wall that is hypothesized to serve as a physical barrier and platform for directed antimicrobial compound deposition. The defense-associated function of callose deposition is supported by its induction during pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI) and its inhibition by defense suppressing virulence effectors. Thus, callose deposition is a commonly monitored read-out in plant defense. This protocol describes the use of aniline blue staining and fluorescent microscopy to measure callose deposition in bacteria-infected or elicitor-challenged Arabidopsis leaf tissues.
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19
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Jin L, Ham JH, Hage R, Zhao W, Soto-Hernández J, Lee SY, Paek SM, Kim MG, Boone C, Coplin DL, Mackey D. Direct and Indirect Targeting of PP2A by Conserved Bacterial Type-III Effector Proteins. PLoS Pathog 2016; 12:e1005609. [PMID: 27191168 PMCID: PMC4871590 DOI: 10.1371/journal.ppat.1005609] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 04/12/2016] [Indexed: 11/19/2022] Open
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.
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Affiliation(s)
- Lin Jin
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jong Hyun Ham
- 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
| | - Rosemary Hage
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Wanying Zhao
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jaricelis Soto-Hernández
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Sang Yeol Lee
- Division of Applied Life Science (BK21Plus), PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Seung-Mann Paek
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Min Gab Kim
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Charles Boone
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - David L. Coplin
- Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - David Mackey
- 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
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20
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Popa C, Coll NS, Valls M, Sessa G. Yeast as a Heterologous Model System to Uncover Type III Effector Function. PLoS Pathog 2016; 12:e1005360. [PMID: 26914889 PMCID: PMC4767418 DOI: 10.1371/journal.ppat.1005360] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Type III effectors (T3E) are key virulence proteins that are injected by bacterial pathogens inside the cells of their host to subvert cellular processes and contribute to disease. The budding yeast Saccharomyces cerevisiae represents an important heterologous system for the functional characterisation of T3E proteins in a eukaryotic environment. Importantly, yeast contains eukaryotic processes with low redundancy and are devoid of immunity mechanisms that counteract T3Es and mask their function. Expression in yeast of effectors from both plant and animal pathogens that perturb conserved cellular processes often resulted in robust phenotypes that were exploited to elucidate effector functions, biochemical properties, and host targets. The genetic tractability of yeast and its amenability for high-throughput functional studies contributed to the success of this system that, in recent years, has been used to study over 100 effectors. Here, we provide a critical view on this body of work and describe advantages and limitations inherent to the use of yeast in T3E research. “Favourite” targets of T3Es in yeast are cytoskeleton components and small GTPases of the Rho family. We describe how mitogen-activated protein kinase (MAPK) signalling, vesicle trafficking, membrane structures, and programmed cell death are also often altered by T3Es in yeast and how this reflects their function in the natural host. We describe how effector structure–function studies and analysis of candidate targeted processes or pathways can be carried out in yeast. We critically analyse technologies that have been used in yeast to assign biochemical functions to T3Es, including transcriptomics and proteomics, as well as suppressor, gain-of-function, or synthetic lethality screens. We also describe how yeast can be used to select for molecules that block T3E function in search of new antibacterial drugs with medical applications. Finally, we provide our opinion on the limitations of S. cerevisiae as a model system and its most promising future applications.
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Affiliation(s)
- Crina Popa
- Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - Núria S. Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - Marc Valls
- Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
- * E-mail: (GS); (MV)
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (GS); (MV)
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21
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Roper MC, Burbank LP, Williams K, Viravathana P, Tien HY, von Bodman S. A Large Repetitive RTX-Like Protein Mediates Water-Soaked Lesion Development, Leakage of Plant Cell Content and Host Colonization in the Pantoea stewartii subsp. stewartii Pathosystem. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:1374-1382. [PMID: 26284907 DOI: 10.1094/mpmi-05-15-0109-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Pantoea stewartii subsp. stewartii is the etiological agent of Stewart's wilt and is a serious bacterial pathogen affecting sweet corn. During the leaf blight phase, P. stewartii colonizes the leaf apoplast and causes a characteristic water-soaked lesion. The Hrp type III secretion system has been implicated in the water-soaking phenotype, and the goal of this study was to investigate other potential factors that contribute to the plant cellular disruption associated with these lesions. The P. stewartii genome contains a gene encoding a large repetitive RTX toxin, designated rtx2. RTX toxins comprise a large family of pore-forming proteins, which are widely distributed among gram-negative bacteria. These cytotoxins usually lyse their target host cells and cause significant tissue damage as a consequence. We hypothesized that this RTX-like toxin plays a role in the water-soaking phase of infection due to its predicted cytolytic properties. Based on the data reported here, we conclude that RTX2 contributes significantly to the development of water-soaked lesions and leakage of plant cellular contents and is an important pathogenicity factor for P. stewartii.
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Affiliation(s)
- M Caroline Roper
- 1 Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA 92521, U.S.A
| | - Lindsey P Burbank
- 1 Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA 92521, U.S.A
| | - Kayla Williams
- 1 Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA 92521, U.S.A
| | - Polrit Viravathana
- 1 Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA 92521, U.S.A
| | - Hsin-Yu Tien
- 3 Department of Plant Sciences, University of Connecticut, Storrs, CT 06238, U.S.A
| | - Susanne von Bodman
- 2 Division of Molecular and Cellular Biosciences, National Science Foundation, Arlington, VA 22230, U.S.A
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22
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Degrave A, Siamer S, Boureau T, Barny MA. The AvrE superfamily: ancestral type III effectors involved in suppression of pathogen-associated molecular pattern-triggered immunity. MOLECULAR PLANT PATHOLOGY 2015; 16:899-905. [PMID: 25640649 PMCID: PMC6638435 DOI: 10.1111/mpp.12237] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The AvrE superfamily of type III effectors (T3Es) is widespread among type III-dependent phytobacteria and plays a crucial role during bacterial pathogenesis. Members of the AvrE superfamily are vertically inherited core effectors, indicating an ancestral acquisition of these effectors in bacterial plant pathogens. AvrE-T3Es contribute significantly to virulence by suppressing pathogen-associated molecular pattern (PAMP)-triggered immunity. They inhibit salicylic acid-mediated plant defences, interfere with vesicular trafficking and promote bacterial growth in planta. AvrE-T3Es elicit cell death in both host and non-host plants independent of any known plant resistance protein, suggesting an original interaction with the plant immune system. Recent studies in yeast have indicated that they activate protein phosphatase 2A and inhibit serine palmitoyl transferase, the first enzyme of the sphingolipid biosynthesis pathway. In this review, we describe the current picture that has emerged from studies of the different members of this fascinating large family.
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Affiliation(s)
- Alexandre Degrave
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), 49045, Angers, France
- UMR1345, IRHS, Institut National de la Recherche Agronomique (INRA), 49071, Beaucouzé, France
| | - Sabrina Siamer
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Tristan Boureau
- UMR1345, IRHS, Institut National de la Recherche Agronomique (INRA), 49071, Beaucouzé, France
- UMR1345, IRHS, Université d'Angers, SFR 4207 QUASAV, PRES l'UNAM, 49045, Angers, France
| | - Marie-Anne Barny
- UMR1392, INRA, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât á 7ème Etage Case 237, 7 Quai St.-Bernard, 75252, Paris, France
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Xin XF, Nomura K, Ding X, Chen X, Wang K, Aung K, Uribe F, Rosa B, Yao J, Chen J, He SY. Pseudomonas syringae Effector Avirulence Protein E Localizes to the Host Plasma Membrane and Down-Regulates the Expression of the NONRACE-SPECIFIC DISEASE RESISTANCE1/HARPIN-INDUCED1-LIKE13 Gene Required for Antibacterial Immunity in Arabidopsis. PLANT PHYSIOLOGY 2015; 169. [PMID: 26206852 PMCID: PMC4577396 DOI: 10.1104/pp.15.00547] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Many bacterial pathogens of plants and animals deliver effector proteins into host cells to promote infection. Elucidation of how pathogen effector proteins function not only is critical for understanding bacterial pathogenesis but also provides a useful tool in discovering the functions of host genes. In this study, we characterized the Pseudomonas syringae pv tomato DC3000 effector protein Avirulence Protein E (AvrE), the founding member of a widely distributed, yet functionally enigmatic, bacterial effector family. We show that AvrE is localized in the plasma membrane (PM) and PM-associated vesicle-like structures in the plant cell. AvrE contains two physically interacting domains, and the amino-terminal portion contains a PM-localization signal. Genome-wide microarray analysis indicates that AvrE, as well as the functionally redundant effector Hypersensitive response and pathogenicity-dependent Outer Protein M1, down-regulates the expression of the NONRACE-SPECIFIC DISEASE RESISTANCE1/HARPIN-INDUCED1-LIKE13 (NHL13) gene in Arabidopsis (Arabidopsis thaliana). Mutational analysis shows that NHL13 is required for plant immunity, as the nhl13 mutant plant displayed enhanced disease susceptibility. Our results defined the action site of one of the most important bacterial virulence proteins in plants and the antibacterial immunity function of the NHL13 gene.
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Affiliation(s)
- Xiu-Fang Xin
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Kinya Nomura
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Xinhua Ding
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Xujun Chen
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Kun Wang
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Kyaw Aung
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Francisco Uribe
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Bruce Rosa
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Jian Yao
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Jin Chen
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
| | - Sheng Yang He
- Department of Energy Plant Research Laboratory (X.-F.X., K.N., X.D., X.C., K.A., F.U., B.R., J.Y., J.C., S.Y.H.), Department of Plant Biology (X.-F.X.), Department of Biochemistry and Molecular Biology (K.W.), and Howard Hughes Medical Institute (S.Y.H.), Michigan State University, East Lansing, Michigan 48824;State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory of Agricultural Microbiology, Shandong Agricultural University, Tai'an, 271018 Shandong, China (X.D.);Key Laboratory of Plant Pathology, Department of Plant Pathology, China Agricultural University, Beijing 100193, China (X.C.);Genome Institute, Washington University, St. Louis, Missouri 63108 (B.R.); andDepartment of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008 (J.Y.)
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24
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Walterson AM, Stavrinides J. Pantoea:insights into a highly versatile and diverse genus within the Enterobacteriaceae. FEMS Microbiol Rev 2015; 39:968-84. [DOI: 10.1093/femsre/fuv027] [Citation(s) in RCA: 265] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 12/31/2022] Open
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25
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Inheritance of Pantoea type III secretion systems through both vertical and horizontal transfer. Mol Genet Genomics 2015; 290:2075-88. [DOI: 10.1007/s00438-015-1062-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/03/2015] [Indexed: 11/26/2022]
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26
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Asselin JAE, Lin J, Perez-Quintero AL, Gentzel I, Majerczak D, Opiyo SO, Zhao W, Paek SM, Kim MG, Coplin DL, Blakeslee JJ, Mackey D. Perturbation of maize phenylpropanoid metabolism by an AvrE family type III effector from Pantoea stewartii. PLANT PHYSIOLOGY 2015; 167:1117-35. [PMID: 25635112 PMCID: PMC4348765 DOI: 10.1104/pp.114.253120] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/24/2015] [Indexed: 05/20/2023]
Abstract
AvrE family type III effector proteins share the ability to suppress host defenses, induce disease-associated cell death, and promote bacterial growth. However, despite widespread contributions to numerous bacterial diseases in agriculturally important plants, the mode of action of these effectors remains largely unknown. WtsE is an AvrE family member required for the ability of Pantoea stewartii ssp. stewartii (Pnss) to proliferate efficiently and cause wilt and leaf blight symptoms in maize (Zea mays) plants. Notably, when WtsE is delivered by a heterologous system into the leaf cells of susceptible maize seedlings, it alone produces water-soaked disease symptoms reminiscent of those produced by Pnss. Thus, WtsE is a pathogenicity and virulence factor in maize, and an Escherichia coli heterologous delivery system can be used to study the activity of WtsE in isolation from other factors produced by Pnss. Transcriptional profiling of maize revealed the effects of WtsE, including induction of genes involved in secondary metabolism and suppression of genes involved in photosynthesis. Targeted metabolite quantification revealed that WtsE perturbs maize metabolism, including the induction of coumaroyl tyramine. The ability of mutant WtsE derivatives to elicit transcriptional and metabolic changes in susceptible maize seedlings correlated with their ability to promote disease. Furthermore, chemical inhibitors that block metabolic flux into the phenylpropanoid pathways targeted by WtsE also disrupted the pathogenicity and virulence activity of WtsE. While numerous metabolites produced downstream of the shikimate pathway are known to promote plant defense, our results indicate that misregulated induction of phenylpropanoid metabolism also can be used to promote pathogen virulence.
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Affiliation(s)
- Jo Ann E Asselin
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Jinshan Lin
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Alvaro L Perez-Quintero
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Irene Gentzel
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Doris Majerczak
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Stephen O Opiyo
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Wanying Zhao
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Seung-Mann Paek
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Min Gab Kim
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - David L Coplin
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Joshua J Blakeslee
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - David Mackey
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
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Transcriptome-based analysis of the Pantoea stewartii quorum-sensing regulon and identification of EsaR direct targets. Appl Environ Microbiol 2014; 80:5790-800. [PMID: 25015891 DOI: 10.1128/aem.01489-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pantoea stewartii subsp. stewartii is a proteobacterium that causes Stewart's wilt disease in corn plants. The bacteria form a biofilm in the xylem of infected plants and produce capsule that blocks water transport, eventually causing wilt. At low cell densities, the quorum-sensing (QS) regulatory protein EsaR is known to directly repress expression of esaR itself as well as the genes for the capsular synthesis operon transcription regulator, rcsA, and a 2,5-diketogluconate reductase, dkgA. It simultaneously directly activates expression of genes for a putative small RNA, esaS, the glycerol utilization operon, glpFKX, and another transcriptional regulator, lrhA. At high bacterial cell densities, all of this regulation is relieved when EsaR binds an acylated homoserine lactone signal, which is synthesized constitutively over growth. QS-dependent gene expression is critical for the establishment of disease in the plant. However, the identity of the full set of genes controlled by EsaR/QS is unknown. A proteomic approach previously identified around 30 proteins in the QS regulon. In this study, a whole-transcriptome, next-generation sequencing analysis of rRNA-depleted RNA from QS-proficient and -deficient P. stewartii strains was performed to identify additional targets of EsaR. EsaR-dependent transcriptional regulation of a subset of differentially expressed genes was confirmed by quantitative reverse transcription-PCR (qRT-PCR). Electrophoretic mobility shift assays demonstrated that EsaR directly bound 10 newly identified target promoters. Overall, the QS regulon of P. stewartii orchestrates three major physiological responses: capsule and cell envelope biosynthesis, surface motility and adhesion, and stress response.
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Siamer S, Guillas I, Shimobayashi M, Kunz C, Hall MN, Barny MA. Expression of the bacterial type III effector DspA/E in Saccharomyces cerevisiae down-regulates the sphingolipid biosynthetic pathway leading to growth arrest. J Biol Chem 2014; 289:18466-77. [PMID: 24828506 DOI: 10.1074/jbc.m114.562769] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Erwinia amylovora, the bacterium responsible for fire blight, relies on a type III secretion system and a single injected effector, DspA/E, to induce disease in host plants. DspA/E belongs to the widespread AvrE family of type III effectors that suppress plant defense responses and promote bacterial growth following infection. Ectopic expression of DspA/E in plant or in Saccharomyces cerevisiae is toxic, indicating that DspA/E likely targets a cellular process conserved between yeast and plant. To unravel the mode of action of DspA/E, we screened the Euroscarf S. cerevisiae library for mutants resistant to DspA/E-induced growth arrest. The most resistant mutants (Δsur4, Δfen1, Δipt1, Δskn1, Δcsg1, Δcsg2, Δorm1, and Δorm2) were impaired in the sphingolipid biosynthetic pathway. Exogenously supplied sphingolipid precursors such as the long chain bases (LCBs) phytosphingosine and dihydrosphingosine also suppressed the DspA/E-induced yeast growth defect. Expression of DspA/E in yeast down-regulated LCB biosynthesis and induced a rapid decrease in LCB levels, indicating that serine palmitoyltransferase (SPT), the first and rate-limiting enzyme of the sphingolipid biosynthetic pathway, was repressed. SPT down-regulation was mediated by dephosphorylation and activation of Orm proteins that negatively regulate SPT. A Δcdc55 mutation affecting Cdc55-PP2A protein phosphatase activity prevented Orm dephosphorylation and suppressed DspA/E-induced growth arrest.
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Affiliation(s)
- Sabrina Siamer
- From the Institut National de la Recherche Agronomique UMR1392, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât A 7ème Etage Case 237, 7 Quai St.-Bernard, 75252 Paris, France, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Isabelle Guillas
- Sorbonne Universités, UMR1166, Institut National de la Santé et de la recherche médicale-UPMC, Pitié-Salpétrière University Hospital, F75013, Paris, France
| | | | - Caroline Kunz
- Sorbonne Universités, UPMC University Paris 06, UFR 927, F-75005 Paris, France, and Muséum National d'Histoire Naturelle, UMR7245, Molécules de Communication et Adaptation des Micro-organismes, F-75005 Paris, France
| | - Michael N Hall
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Marie-Anne Barny
- From the Institut National de la Recherche Agronomique UMR1392, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât A 7ème Etage Case 237, 7 Quai St.-Bernard, 75252 Paris, France,
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Siamer S, Gaubert S, Boureau T, Brisset MN, Barny MA. Mutational analysis of a predicted double β-propeller domain of the DspA/E effector of Erwinia amylovora. FEMS Microbiol Lett 2013; 342:54-61. [PMID: 23421848 DOI: 10.1111/1574-6968.12108] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 02/07/2013] [Accepted: 02/18/2013] [Indexed: 12/11/2022] Open
Abstract
The bacterium Erwinia amylovora causes fire blight, an invasive disease that threatens apple trees, pear trees and other plants of the Rosaceae family. Erwinia amylovora pathogenicity relies on a type III secretion system and on a single effector DspA/E. This effector belongs to the widespread AvrE family of effectors whose biological function is unknown. In this manuscript, we performed a bioinformatic analysis of DspA/E- and AvrE-related effectors. Motif search identified nuclear localization signals, peroxisome targeting signals, endoplasmic reticulum membrane retention signals and leucine zipper motifs, but none of these motifs were present in all the AvrE-related effectors analysed. Protein threading analysis, however, predicted a conserved double β-propeller domain in the N-terminal part of all the analysed effector sequences. We then performed a random pentapeptide mutagenesis of DspA/E, which led to the characterization of 13 new altered proteins with a five amino acids insertion. Eight harboured the insertion inside the predicted β-propeller domain and six of these eight insertions impaired DspA/E stability or function. Conversely, the two remaining insertions generated proteins that were functional and abundantly secreted in the supernatant suggesting that these two insertions stabilized the protein.
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Hogan CS, Mole BM, Grant SR, Willis DK, Charkowski AO. The type III secreted effector DspE is required early in solanum tuberosum leaf infection by Pectobacterium carotovorum to cause cell death, and requires Wx(3-6)D/E motifs. PLoS One 2013; 8:e65534. [PMID: 23755246 PMCID: PMC3670860 DOI: 10.1371/journal.pone.0065534] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 04/29/2013] [Indexed: 11/23/2022] Open
Abstract
Pectobacterium species are enterobacterial plant-pathogens that cause soft rot disease in diverse plant species. Unlike hemi-biotrophic plant pathogenic bacteria, the type III secretion system (T3SS) of Pectobacterium carotovorum subsp. carotovorum (P. carotovorum) appears to secrete only one effector protein, DspE. Previously, we found that the T3SS regulator HrpL and the effector DspE are required for P. carotovorum pathogenesis on leaves. Here, we identified genes up-regulated by HrpL, visualized expression of dspE in leaves, and established that DspE causes host cell death. DspE required its full length and WxxxE-like motifs, which are characteristic of the AvrE-family effectors, for host cell death. We also examined expression in plant leaves and showed that hrpL is required for the expression of dspE and hrpN, and that the loss of a functional T3SS had unexpected effects on expression of other genes during leaf infection. These data support a model where P. carotovorum uses the T3SS early in leaf infection to initiate pathogenesis through elicitation of DspE-mediated host cell death.
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Affiliation(s)
- Clifford S. Hogan
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Beth M. Mole
- Department of Biology and Curriculum in Molecular Biology and Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sarah R. Grant
- Department of Biology and Curriculum in Molecular Biology and Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - David K. Willis
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Vegetable Crops Research Unit, United States Department of Agriculture – Agricultural Research Service, Madison, Wisconsin, United States of America
| | - Amy O. Charkowski
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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Degrave A, Moreau M, Launay A, Barny MA, Brisset MN, Patrit O, Taconnat L, Vedel R, Fagard M. The bacterial effector DspA/E is toxic in Arabidopsis thaliana and is required for multiplication and survival of fire blight pathogen. MOLECULAR PLANT PATHOLOGY 2013; 14:506-17. [PMID: 23634775 PMCID: PMC6638835 DOI: 10.1111/mpp.12022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The type III effector DspA/E is an essential pathogenicity factor of the phytopathogenic bacterium Erwinia amylovora. We showed that DspA/E was required for transient bacterial growth in nonhost Arabidopsis thaliana leaves, as an E. amylovora dspA/E mutant was unable to grow. We expressed DspA/E in A. thaliana transgenic plants under the control of an oestradiol-inducible promoter, and found that DspA/E expressed in planta restored the growth of a dspA/E mutant. DspA/E expression in these transgenic plants led to the modulation by at least two-fold of the expression of 384 genes, mostly induced (324 genes). Both induced and repressed genes contained high proportions of defence genes. DspA/E expression ultimately resulted in plant cell death without requiring a functional salicylic acid signalling pathway. Analysis of A. thaliana transgenic seedlings expressing a green fluorescent protein (GFP):DspA/E fusion indicated that the fusion protein could only be detected in a few cells per seedling, suggesting the degradation or absence of accumulation of DspA/E in plant cells. Consistently, we found that DspA/E repressed plant protein synthesis when injected by E. amylovora or when expressed in transgenic plants. Thus, we conclude that DspA/E is toxic to A. thaliana: it promotes modifications, among which the repression of protein synthesis could be determinant in the facilitation of necrosis and bacterial growth.
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Affiliation(s)
- Alexandre Degrave
- INRA, Laboratoire des Interactions Plantes Pathogènes, UMR217 Paris, France
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Chen S, Songkumarn P, Venu RC, Gowda M, Bellizzi M, Hu J, Liu W, Ebbole D, Meyers B, Mitchell T, Wang GL. Identification and characterization of in planta-expressed secreted effector proteins from Magnaporthe oryzae that induce cell death in rice. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:191-202. [PMID: 23035914 DOI: 10.1094/mpmi-05-12-0117-r] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Interactions between rice and Magnaporthe oryzae involve the recognition of cellular components and the exchange of complex molecular signals from both partners. How these interactions occur in rice cells is still elusive. We employed robust-long serial analysis of gene expression, massively parallel signature sequencing, and sequencing by synthesis to examine transcriptome profiles of infected rice leaves. A total of 6,413 in planta-expressed fungal genes, including 851 genes encoding predicted effector proteins, were identified. We used a protoplast transient expression system to assess 42 of the predicted effector proteins for the ability to induce plant cell death. Ectopic expression assays identified five novel effectors that induced host cell death only when they contained the signal peptide for secretion to the extracellular space. Four of them induced cell death in Nicotiana benthamiana. Although the five effectors are highly diverse in their sequences, the physiological basis of cell death induced by each was similar. This study demonstrates that our integrative genomic approach is effective for the identification of in planta-expressed cell death-inducing effectors from M. oryzae that may play an important role facilitating colonization and fungal growth during infection.
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Affiliation(s)
- Songbiao Chen
- State Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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Zhou J, Spallek T, Faulkner C, Robatzek S. CalloseMeasurer: a novel software solution to measure callose deposition and recognise spreading callose patterns. PLANT METHODS 2012; 8:49. [PMID: 23244621 PMCID: PMC3571893 DOI: 10.1186/1746-4811-8-49] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 12/13/2012] [Indexed: 05/03/2023]
Abstract
BACKGROUND Quantification of callose deposits is a useful measure for the activities of plant immunity and pathogen growth by fluorescence imaging. For robust scoring of differences, this normally requires many technical and biological replicates and manual or automated quantification of the callose deposits. However, previously available software tools for quantifying callose deposits from bioimages were limited, making batch processing of callose image data problematic. In particular, it is challenging to perform large-scale analysis on images with high background noise and fused callose deposition signals. RESULTS We developed CalloseMeasurer, an easy-to-use application that quantifies callose deposition, a plant immune response triggered by potentially pathogenic microbes. Additionally, by tracking identified callose deposits between multiple images, the software can recognise patterns of how a given filamentous pathogen grows in plant leaves. The software has been evaluated with typical noisy experimental images and can be automatically executed without the need for user intervention. The automated analysis is achieved by using standard image analysis functions such as image enhancement, adaptive thresholding, and object segmentation, supplemented by several novel methods which filter background noise, split fused signals, perform edge-based detection, and construct networks and skeletons for extracting pathogen growth patterns. To efficiently batch process callose images, we implemented the algorithm in C/C++ within the Acapella™ framework. Using the tool we can robustly score significant differences between different plant genotypes when activating the immune response. We also provide examples for measuring the in planta hyphal growth of filamentous pathogens. CONCLUSIONS CalloseMeasurer is a new software solution for batch-processing large image data sets to quantify callose deposition in plants. We demonstrate its high accuracy and usefulness for two applications: 1) the quantification of callose deposition in different genotypes as a measure for the activity of plant immunity; and 2) the quantification and detection of spreading networks of callose deposition triggered by filamentous pathogens as a measure for growing pathogen hyphae. The software is an easy-to-use protocol which is executed within the Acapella software system without requiring any additional libraries. The source code of the software is freely available at https://sourceforge.net/projects/bioimage/files/Callose.
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Affiliation(s)
- Ji Zhou
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Thomas Spallek
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
- Present address: RIKEN Yokohama Institute, Suehiro-cho, Tsurumi-ku, Yokohama City, Kanagawa, 230-0045, Japan
| | - Christine Faulkner
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
- Present address: Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Silke Robatzek
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
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Salomon D, Bosis E, Dar D, Nachman I, Sessa G. Expression of Pseudomonas syringae type III effectors in yeast under stress conditions reveals that HopX1 attenuates activation of the high osmolarity glycerol MAP kinase pathway. MICROBIOLOGY-SGM 2012; 158:2859-2869. [PMID: 22977090 DOI: 10.1099/mic.0.062513-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The Gram-negative bacterium Pseudomonas syringae pv. tomato (Pst) is the causal agent of speck disease in tomato. Pst pathogenicity depends on a type III secretion system that delivers effector proteins into host cells, where they promote disease by manipulating processes to the advantage of the pathogen. Previous studies identified seven Pst effectors that inhibit growth when expressed in yeast under normal growth conditions, suggesting that they interfere with cellular processes conserved in yeast and plants. We hypothesized that effectors also target conserved cellular processes that are required for yeast growth only under stress conditions. We therefore examined phenotypes induced by expression of Pst effectors in yeast grown in the presence of various stressors. Out of 29 effectors tested, five (HopX1, HopG1, HopT1-1, HopH1 and AvrPtoB) displayed growth inhibition phenotypes only in combination with stress conditions. Viability assays revealed that the HopX1 effector caused loss of cell viability under prolonged osmotic stress. Using transcription reporters, we found that HopX1 attenuated the activation of the high osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway, which is responsible for yeast survival under osmotic stress, while other MAPK pathways were mildly affected by HopX1. Interestingly, HopX1-mediated phenotypes in yeast were dependent on the putative transglutaminase catalytic triad of the effector. This study enlarges the pool of phenotypes available for the functional analysis of Pst type III effectors in yeast, and exemplifies how analysis of phenotypes detected in yeast under stress conditions can lead to the identification of eukaryotic cellular processes affected by bacterial effectors.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Eran Bosis
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Daniel Dar
- Department of Biochemistry and Molecular Biology, Tel Aviv University, 69978 Tel Aviv, Israel
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Iftach Nachman
- Department of Biochemistry and Molecular Biology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
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Siamer S, Patrit O, Fagard M, Belgareh-Touzé N, Barny MA. Expressing the Erwinia amylovora type III effector DspA/E in the yeast Saccharomyces cerevisiae strongly alters cellular trafficking. FEBS Open Bio 2011; 1:23-8. [PMID: 23650572 PMCID: PMC3642059 DOI: 10.1016/j.fob.2011.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/02/2011] [Accepted: 11/03/2011] [Indexed: 11/18/2022] Open
Abstract
Erwinia amylovora is responsible for fire blight, a necrotic disease of apples and pears. E. amylovora relies on a type III secretion system (T3SS) to induce disease on host plants. DspA/E belongs to the AvrE family of type III effector. Effectors of the AvrE family are injected via the T3SS in plant cell and are important to promote bacterial growth following infection and to suppress plant defense responses. Their mode of action in the plant cells is unknown. Here we study the physiological effects induced by dspA/E expression in the yeast Saccharomyces cerevisiae. Expression of dspA/E in the yeast inhibits cell growth. This growth inhibition is associated with perturbations of the actin cytoskeleton and endocytosis.
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Affiliation(s)
- Sabrina Siamer
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Oriane Patrit
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Mathilde Fagard
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Naïma Belgareh-Touzé
- FRE 3354 CNRS/UPMC, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Marie-Anne Barny
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- Corresponding author at: AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France. Fax: +33 1 44 08 16 98.
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Roper MC. Pantoea stewartii subsp. stewartii: lessons learned from a xylem-dwelling pathogen of sweet corn. MOLECULAR PLANT PATHOLOGY 2011; 12:628-37. [PMID: 21726365 PMCID: PMC6640275 DOI: 10.1111/j.1364-3703.2010.00698.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
UNLABELLED Pantoea stewartii subsp. stewartii is a Gram-negative enteric bacterium that primarily infects sweet corn. Studies of this bacterium have provided useful insight into how xylem-dwelling bacteria establish themselves and incite disease in their hosts. Pantoea stewartii subsp. stewartii is a remarkable bacterial system for laboratory studies because of its relative ease of propagation and genetic manipulation, and the fact that it appears to employ a minimal number of pathogenicity mechanisms. In addition, P. stewartii subsp. stewartii produces copious amounts of its quorum sensing (QS) signal, acyl-homoserine lactone (AHL), making it an excellent organism for studying QS-controlled gene regulation in a plant-pathogenic bacterium. In fact, P. stewartii subsp. stewartii has become the microbial paradigm for QS control of gene expression by both repression and activation via a QS regulator that binds DNA in the absence and dissociates in the presence of the signal ligand. Moreover, P. stewartii subsp. stewartii is a member of the Enterobacteriaceae, and lessons learned from its interaction with plants may be extrapolated to other plant-associated enterics, such as Erwinia, Dickeya and Pectobacterium spp., or enteric human pathogens associated with plants, such as Escherichia coli and Salmonella spp. TAXONOMY Bacteria; Gammaproteobacteria; family Enterobacteriaceae; genus Pantoea; species stewartii (Mergaert et al., 1993). MICROBIOLOGICAL PROPERTIES Gram-negative, motile, yellow pigmented, mucoid, facultative anaerobe. HOST RANGE Pantoea stewartii subsp. stewartii (Smith, 1898) Dye causes Stewart's wilt of corn (Zea mays). Early-maturing sweet corn varieties and some elite inbred maize lines are particularly susceptible. DISEASE SYMPTOMS There are two major phases of Stewart's wilt disease: (i) wilt and (ii) leaf blight. The wilt phase occurs when young seedlings are infected with P. stewartii subsp. stewartii (Fig. 1A). Water-soaked lesions first appear on the young expanding leaves and, later, seedlings may become severely wilted (Fig. 1B). The plants usually die when infected at the seedling stage. The leaf blight phase occurs when mature plants are infected (Fig. 1C). The bacteria enter the xylem and cause long linear yellow-grey lesions with a wavy margin that run parallel to the leaf veins. These lesions later turn necrotic and dark in colour. The leaf blight phase is most apparent after tasselling and does not generally cause death of the plant. In addition, the bacteria can sometimes break out of the xylem and cause pith rot in mature sweet corn plants. In resistant varieties, lesions are usually limited to only a few centimetres depending on the level of resistance of the particular hybrid (Claflin, 2000; Pataky, 2003). USEFUL WEBSITES http://www.apsnet.org/publications/apsnetfeatures/Pages/StewartsWilt.aspx.
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Affiliation(s)
- M Caroline Roper
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA.
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Kim HS, Thammarat P, Lommel SA, Hogan CS, Charkowski AO. Pectobacterium carotovorum elicits plant cell death with DspE/F but the P. carotovorum DspE does not suppress callose or induce expression of plant genes early in plant-microbe interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:773-86. [PMID: 21469936 DOI: 10.1094/mpmi-06-10-0143] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The broad-host-range bacterial soft rot pathogen Pectobacterium carotovorum causes a DspE/F-dependent plant cell death on Nicotiana benthamiana within 24 h postinoculation (hpi) followed by leaf maceration within 48 hpi. P. carotovorum strains with mutations in type III secretion system (T3SS) regulatory and structural genes, including the dspE/F operon, did not cause hypersensitive response (HR)-like cell death and or leaf maceration. A strain with a mutation in the type II secretion system caused HR-like plant cell death but no maceration. P. carotovorum was unable to impede callose deposition in N. benthamiana leaves, suggesting that P. carotovorum does not suppress this basal immunity function. Within 24 hpi, there was callose deposition along leaf veins and examination showed that the pathogen cells were localized along the veins. To further examine HR-like plant cell death induced by P. carotovorum, gene expression profiles in N. benthamiana leaves inoculated with wild-type and mutant P. carotovorum and Pseudomonas syringae strains were compared. The N. benthamiana gene expression profile of leaves infiltrated with Pectobacterium carotovorum was similar to leaves infiltrated with a Pseudomonas syringae T3SS mutant. These data support a model where Pectobacterium carotovorum uses the T3SS to induce plant cell death in order to promote leaf maceration rather than to suppress plant immunity.
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Affiliation(s)
- Hye-Sook Kim
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
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Ham JH, Majerczak DR, Nomura K, Mecey C, Uribe F, He SY, Mackey D, Coplin DL. Multiple activities of the plant pathogen type III effector proteins WtsE and AvrE require WxxxE motifs. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:703-12. [PMID: 19445595 PMCID: PMC2748107 DOI: 10.1094/mpmi-22-6-0703] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The broadly conserved AvrE-family of type III effectors from gram-negative plant-pathogenic bacteria includes important virulence factors, yet little is known about the mechanisms by which these effectors function inside plant cells to promote disease. We have identified two conserved motifs in AvrE-family effectors: a WxxxE motif and a putative C-terminal endoplasmic reticulum membrane retention/retrieval signal (ERMRS). The WxxxE and ERMRS motifs are both required for the virulence activities of WtsE and AvrE, which are major virulence factors of the corn pathogen Pantoea stewartii subsp. stewartii and the tomato or Arabidopsis pathogen Pseudomonas syringae pv. tomato, respectively. The WxxxE and the predicted ERMRS motifs are also required for other biological activities of WtsE, including elicitation of the hypersensitive response in nonhost plants and suppression of defense responses in Arabidopsis. A family of type III effectors from mammalian bacterial pathogens requires WxxxE and subcellular targeting motifs for virulence functions that involve their ability to mimic activated G-proteins. The conservation of related motifs and their necessity for the function of type III effectors from plant pathogens indicates that disturbing host pathways by mimicking activated host G-proteins may be a virulence mechanism employed by plant pathogens as well.
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Affiliation(s)
- Jong Hyun Ham
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, 43210
- Department of Plant Pathology, The Ohio State University, Columbus, OH, 43210
| | - Doris R. Majerczak
- Department of Plant Pathology, The Ohio State University, Columbus, OH, 43210
| | - Kinya Nomura
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - Christy Mecey
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - Francisco Uribe
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - Sheng-Yang He
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824
| | - David Mackey
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, 43210
| | - David L. Coplin
- Department of Plant Pathology, The Ohio State University, Columbus, OH, 43210
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