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Chiang BJ, Lin KY, Chen YF, Huang CY, Goh FJ, Huang LT, Chen LH, Wu CH. Development of a tightly regulated copper-inducible transient gene expression system in Nicotiana benthamiana incorporating a suicide exon and Cre recombinase. THE NEW PHYTOLOGIST 2024; 244:318-331. [PMID: 39081031 DOI: 10.1111/nph.20021] [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: 03/16/2024] [Accepted: 07/15/2024] [Indexed: 09/17/2024]
Abstract
Chemical-inducible gene expression systems are commonly used to regulate gene expression for functional genomics in various plant species. However, a convenient system that can tightly regulate transgene expression in Nicotiana benthamiana is still lacking. In this study, we developed a tightly regulated copper-inducible system that can control transgene expression and conduct cell death assays in N. benthamiana. We tested several chemical-inducible systems using Agrobacterium-mediated transient expression and found that the copper-inducible system exhibited the least concerns regarding leakiness in N. benthamiana. Although the copper-inducible system can control the expression of some tested reporters, it is not sufficiently tight to regulate certain tested hypersensitive cell death responses. Using the MoClo-based synthetic biology approach, we incorporated the suicide exon HyP5SM/OsL5 and Cre/LoxP as additional regulatory elements to enhance the tightness of the regulation. This new design allowed us to tightly control the hypersensitive cell death induced by several tested leucine-rich repeat-containing proteins and their matching avirulence factors, and it can be easily applied to regulate the expression of other transgenes in transient expression assays. Our findings offer new approaches for both fundamental and translational studies in plant functional genomics.
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Affiliation(s)
- Bing-Jen Chiang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115 201, Taiwan
| | - Kuan-Yu Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115 201, Taiwan
| | - Yi-Feng Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115 201, Taiwan
| | - Ching-Yi Huang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115 201, Taiwan
| | - Foong-Jing Goh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115 201, Taiwan
| | - Lo-Ting Huang
- Department of Plant Pathology, National Chung Hsing University, Taichung, 402 202, Taiwan
| | - Li-Hung Chen
- Department of Plant Pathology, National Chung Hsing University, Taichung, 402 202, Taiwan
- Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung, 402 202, Taiwan
| | - Chih-Hang Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115 201, Taiwan
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2
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Hershkovitz D, Chen EJ, Ensminger AW, Dugan AS, Conway KT, Joyce AC, Segal G, Isberg RR. Genetic evidence for a regulated cysteine protease catalytic triad in LegA7, a Legionella pneumophila protein that impinges on a stress response pathway. mSphere 2024; 9:e0022224. [PMID: 39166849 PMCID: PMC11423584 DOI: 10.1128/msphere.00222-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 06/30/2024] [Indexed: 08/23/2024] Open
Abstract
Legionella pneumophila grows within membrane-bound vacuoles in phylogenetically diverse hosts. Intracellular growth requires the function of the Icm/Dot type-IVb secretion system, which translocates more than 300 proteins into host cells. A screen was performed to identify L. pneumophila proteins that stimulate mitogen-activated protein kinase (MAPK) activation, using Icm/Dot translocated proteins ectopically expressed in mammalian cells. In parallel, a second screen was performed to identify L. pneumophila proteins expressed in yeast that cause growth inhibition in MAPK pathway-stimulatory high-osmolarity medium. LegA7 was shared in both screens, a protein predicted to be a member of the bacterial cysteine protease family that has five carboxyl-terminal ankyrin repeats. Three conserved residues in the predicted catalytic triad of LegA7 were mutated. These mutations abolished the ability of LegA7 to inhibit yeast growth. To identify other residues important for LegA7 function, a generalizable selection strategy in yeast was devised to isolate mutants that have lost function and no longer cause growth inhibition on a high-osmolarity medium. Mutations were isolated in the two carboxyl-terminal ankyrin repeats, as well as an inter-domain region located between the cysteine protease domain and the ankyrin repeats. These mutations were predicted by AlphaFold modeling to localize to the face opposite from the catalytic site, arguing that they interfere with the positive regulation of the catalytic activity. Based on our data, we present a model in which LegA7 harbors a cysteine protease domain with an inter-domain and two carboxyl-terminal ankyrin repeat regions that modulate the function of the catalytic domain. IMPORTANCE Legionella pneumophila grows in a membrane-bound compartment in macrophages during disease. Construction of the compartment requires a dedicated secretion system that translocates virulence proteins into host cells. One of these proteins, LegA7, is shown to activate a stress response pathway in host cells called the mitogen-activated protein kinase (MAPK) pathway. The effects on the mammalian MAPK pathway were reconstructed in yeast, allowing the development of a strategy to identify the role of individual domains of LegA7. A domain similar to cysteine proteases is demonstrated to be critical for impinging on the MAPK pathway, and the catalytic activity of this domain is required for targeting this path. In addition, a conserved series of repeats, called ankyrin repeats, controls this activity. Data are provided that argue the interaction of the ankyrin repeats with unknown targets probably results in activation of the cysteine protease domain.
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Affiliation(s)
- Dar Hershkovitz
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Emy J Chen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Program in Genetics, Molecular and Cellular Biology, Graduate School of Biomedical Sciences Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Alexander W Ensminger
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Aisling S Dugan
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Kaleigh T Conway
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Program in Genetics, Molecular and Cellular Biology, Graduate School of Biomedical Sciences Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Alex C Joyce
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Gil Segal
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Ralph R Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
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3
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Yang X, Gan Y, Zhang Y, Liu Z, Geng J, Wang W. Microbial genotoxin-elicited host DNA mutations related to mitochondrial dysfunction, a momentous contributor for colorectal carcinogenesis. mSystems 2024; 9:e0088724. [PMID: 39189772 PMCID: PMC11406885 DOI: 10.1128/msystems.00887-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2024] Open
Abstract
Gut microbe dysbiosis increases repetitive inflammatory responses, leading to an increase in the incidence of colorectal cancer. Recent studies have revealed that specific microbial species directly instigate mutations in the host nucleus DNA, thereby accelerating the progression of colorectal cancer. Given the well-established role of mitochondrial dysfunction in promoting colorectal cancer, it is reasonable to postulate that gut microbes may induce mitochondrial gene mutations, thereby inducing mitochondrial dysfunction. In this review, we focus on gut microbial genotoxins and their known and potential targets in mitochondrial genes. Consequently, we propose that targeted disruption of genotoxin transport pathways may effectively reduce the rate of mitochondrial gene mutations and yield substantial benefits for the prevention of colorectal carcinogenesis.
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Affiliation(s)
- Xue Yang
- Department of Infectious Disease and Hepatic Disease, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan Province, Kunming, Yunnan, China
- School of Medicine, Kunming University of Science and Technology, Kunming, Yunnan, China
| | - Yumeng Gan
- Department of Infectious Disease and Hepatic Disease, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan Province, Kunming, Yunnan, China
- School of Medicine, Kunming University of Science and Technology, Kunming, Yunnan, China
| | - Yuting Zhang
- Department of Infectious Disease and Hepatic Disease, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan Province, Kunming, Yunnan, China
| | - Zhongjian Liu
- Institute of Basic and Clinical Medicine, First People's Hospital of Yunnan Province, Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan, China
| | - Jiawei Geng
- Department of Infectious Disease and Hepatic Disease, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan Province, Kunming, Yunnan, China
- School of Medicine, Kunming University of Science and Technology, Kunming, Yunnan, China
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, China
| | - Wenxue Wang
- Department of Infectious Disease and Hepatic Disease, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan Province, Kunming, Yunnan, China
- School of Medicine, Kunming University of Science and Technology, Kunming, Yunnan, China
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, China
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4
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Hershkovitz D, Chen EJ, Ensminger AW, Dugan AS, Conway KT, Joyce AC, Segal G, Isberg RR. Genetic evidence for a regulated cysteine protease catalytic triad in LegA7, a Legionella pneumophila protein that impinges on a stress response pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.17.585421. [PMID: 38562771 PMCID: PMC10983931 DOI: 10.1101/2024.03.17.585421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Legionella pneumophila grows within membrane-bound vacuoles in phylogenetically diverse hosts. Intracellular growth requires the function of the Icm/Dot type-IVb secretion system, which translocates more than 300 proteins into host cells. A screen was performed to identify L. pneumophila proteins that stimulate MAPK activation, using Icm/Dot translocated proteins ectopically expressed in mammalian cells. In parallel, a second screen was performed to identify L. pneumophila proteins expressed in yeast that cause growth inhibition in MAPK pathway-stimulatory high osmolarity medium. LegA7 was shared in both screens, a protein predicted to be a member of the bacterial cysteine protease family that has five carboxyl-terminal ankyrin repeats. Three conserved residues in the predicted catalytic triad of LegA7 were mutated. These mutations abolished the ability of LegA7 to inhibit yeast growth. To identify other residues important for LegA7 function, a generalizable selection strategy in yeast was devised to isolate mutants that have lost function and no longer cause growth inhibition on high osmolarity medium. Mutations were isolated in the two carboxyl-terminal ankyrin repeats, as well as an inter-domain region located between the cysteine protease domain and the ankyrin repeats. These mutations were predicted by AlphaFold modeling to localize to the face opposite from the catalytic site, arguing that they interfere with the positive regulation of the catalytic activity. Based on our data, we present a model in which LegA7 harbors a cysteine protease domain with an inter-domain and two carboxyl-terminal ankyrin repeat regions that modulate the function of the catalytic domain.
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Affiliation(s)
- Dar Hershkovitz
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Emy J. Chen
- Department of Molecular Biology and Microbiology
- Program in Genetics, Molecular and Cellular Biology, Graduate School of Biomedical Sciences, Tufts University School of Medicine,150 Harrison Ave., Boston, MA 02115, USA
| | | | - Aisling S. Dugan
- Department of Molecular Biology and Microbiology
- Current Address: Dept. of Biology, Brown University, Providence, RI 02912
| | - Kaleigh T. Conway
- Department of Molecular Biology and Microbiology
- Program in Genetics, Molecular and Cellular Biology, Graduate School of Biomedical Sciences, Tufts University School of Medicine,150 Harrison Ave., Boston, MA 02115, USA
| | | | - Gil Segal
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, 6997801, Israel
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5
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Rufián JS, Rueda-Blanco J, Beuzón CR, Ruiz-Albert J. Suppression of NLR-mediated plant immune detection by bacterial pathogens. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6069-6088. [PMID: 37429579 PMCID: PMC10575702 DOI: 10.1093/jxb/erad246] [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: 04/17/2023] [Accepted: 07/10/2023] [Indexed: 07/12/2023]
Abstract
The plant immune system is constituted of two functionally interdependent branches that provide the plant with an effective defense against microbial pathogens. They can be considered separate since one detects extracellular pathogen-associated molecular patterns by means of receptors on the plant surface, while the other detects pathogen-secreted virulence effectors via intracellular receptors. Plant defense depending on both branches can be effectively suppressed by host-adapted microbial pathogens. In this review we focus on bacterially driven suppression of the latter, known as effector-triggered immunity (ETI) and dependent on diverse NOD-like receptors (NLRs). We examine how some effectors secreted by pathogenic bacteria carrying type III secretion systems can be subject to specific NLR-mediated detection, which can be evaded by the action of additional co-secreted effectors (suppressors), implying that virulence depends on the coordinated action of the whole repertoire of effectors of any given bacterium and their complex epistatic interactions within the plant. We consider how ETI activation can be avoided by using suppressors to directly alter compromised co-secreted effectors, modify plant defense-associated proteins, or occasionally both. We also comment on the potential assembly within the plant cell of multi-protein complexes comprising both bacterial effectors and defense protein targets.
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Affiliation(s)
- José S Rufián
- Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Depto. Biología Celular, Genética y Fisiología, Málaga, Spain
| | | | - Carmen R Beuzón
- Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Depto. Biología Celular, Genética y Fisiología, Málaga, Spain
| | - Javier Ruiz-Albert
- Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Depto. Biología Celular, Genética y Fisiología, Málaga, Spain
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6
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Shepherd S, Yuen ELH, Carella P, Bozkurt TO. The wheels of destruction: Plant NLR immune receptors are mobile and structurally dynamic disease resistance proteins. CURRENT OPINION IN PLANT BIOLOGY 2023; 74:102372. [PMID: 37172365 DOI: 10.1016/j.pbi.2023.102372] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/23/2023] [Accepted: 04/04/2023] [Indexed: 05/14/2023]
Abstract
Nucleotide-binding leucine-rich repeat (NLR) proteins are intracellular immune receptors that restrict plant invasion by pathogens. Most NLRs operate in intricate networks to detect pathogen effectors in a robust and efficient manner. NLRs are not static sensors; rather, they exhibit remarkable mobility and structural plasticity during the innate immune response. Inactive NLRs localize to diverse subcellular compartments where they are poised to sense pathogen effectors. During pathogen attack, some NLRs relocate toward the plant-pathogen interface, possibly to ensure their timely activation. Activated NLRs reorganize into wheel-shaped oligomers, some of which then form plasma membrane pores that promote calcium influx and programmed cell death. The emerging paradigm is that this variable and dynamic nature underpins effective NLR-mediated immunity.
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Affiliation(s)
- Samuel Shepherd
- Department of Life Sciences, Imperial College, London, United Kingdom
| | | | | | - Tolga O Bozkurt
- Department of Life Sciences, Imperial College, London, United Kingdom.
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7
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Jeon H, Segonzac C. Manipulation of the Host Endomembrane System by Bacterial Effectors. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2023; 36:208-217. [PMID: 36645655 DOI: 10.1094/mpmi-09-22-0190-fi] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The endomembrane system, extending from the nuclear envelope to the plasma membrane, is critical to the plant response to pathogen infection. Synthesis and transport of immunity-related proteins and antimicrobial compounds to and from the plasma membrane are supported by conventional and unconventional processes of secretion and internalization of vesicles, guided by the cytoskeleton networks. Although plant bacterial pathogens reside mostly in the apoplast, major structural and functional modifications of the endomembrane system in the host cell occur during bacterial infection. Here, we review the dynamics of these cellular compartments, briefly, for their essential contributions to the plant defense responses and, in parallel, for their emerging roles in bacterial pathogenicity. We further focus on Pseudomonas syringae, Xanthomonas spp., and Ralstonia solanacearum type III secreted effectors that one or both localize to and associate with components of the host endomembrane system or the cytoskeleton network to highlight the diversity of virulence strategies deployed by bacterial pathogens beyond the inhibition of the secretory pathway. [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)
- Hyelim Jeon
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Republic of Korea
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Republic of Korea
| | - Cécile Segonzac
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Republic of Korea
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Republic of Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul, 08826, Republic of Korea
- Agricultural and Life Science Research Institute, Seoul National University, Seoul, 08826, Republic of Korea
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8
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Jiménez-Guerrero I, Medina C, Vinardell JM, Ollero FJ, López-Baena FJ. The Rhizobial Type 3 Secretion System: The Dr. Jekyll and Mr. Hyde in the Rhizobium–Legume Symbiosis. Int J Mol Sci 2022; 23:ijms231911089. [PMID: 36232385 PMCID: PMC9569860 DOI: 10.3390/ijms231911089] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/08/2022] [Accepted: 09/14/2022] [Indexed: 01/14/2023] Open
Abstract
Rhizobia are soil bacteria that can establish a symbiotic association with legumes. As a result, plant nodules are formed on the roots of the host plants where rhizobia differentiate to bacteroids capable of fixing atmospheric nitrogen into ammonia. This ammonia is transferred to the plant in exchange of a carbon source and an appropriate environment for bacterial survival. This process is subjected to a tight regulation with several checkpoints to allow the progression of the infection or its restriction. The type 3 secretion system (T3SS) is a secretory system that injects proteins, called effectors (T3E), directly into the cytoplasm of the host cell, altering host pathways or suppressing host defense responses. This secretion system is not present in all rhizobia but its role in symbiosis is crucial for some symbiotic associations, showing two possible faces as Dr. Jekyll and Mr. Hyde: it can be completely necessary for the formation of nodules, or it can block nodulation in different legume species/cultivars. In this review, we compile all the information currently available about the effects of different rhizobial effectors on plant symbiotic phenotypes. These phenotypes are diverse and highlight the importance of the T3SS in certain rhizobium–legume symbioses.
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9
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Khan A, Wadood SF, Chen M, Wang Y, Xie ZP, Staehelin C. Effector-triggered inhibition of nodulation: A rhizobial effector protease targets soybean kinase GmPBS1-1. PLANT PHYSIOLOGY 2022; 189:2382-2395. [PMID: 35543503 PMCID: PMC9343005 DOI: 10.1093/plphys/kiac205] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/01/2022] [Indexed: 05/14/2023]
Abstract
Type III protein secretion systems of nitrogen-fixing rhizobia deliver effector proteins into leguminous host cells to promote or inhibit the nodule symbiosis. However, mechanisms underlying effector-triggered inhibition of nodulation remain largely unknown. Nodulation outer protein T (NopT) of Sinorhizobium sp. NGR234 is an effector protease related to the Pseudomonas effector Avirulence protein Pseudomonas phaseolicola B (AvrPphB). Here, we constructed NGR234 mutants producing different NopT variants and found that protease activity of NopT negatively affects nodulation of smooth crotalaria (Crotalaria pallida). NopT variants lacking residues required for autocleavage and subsequent lipidation showed reduced symbiotic effects and were not targeted to the plasma membrane. We further noticed that Sinorhizobium fredii strains possess a mutated nopT gene. Sinorhizobium fredii USDA257 expressing nopT of NGR234 induced considerably fewer nodules in soybean (Glycine max) cv. Nenfeng 15 but not in other cultivars. Effector perception was further examined in NopT-expressing leaves of Arabidopsis (Arabidopsis thaliana) and found to be dependent on the protein kinase Arabidopsis AvrPphB Susceptible 1 (AtPBS1) and the associated resistance protein Arabidopsis Resistance to Pseudomonas syringae 5 (AtRPS5). Experiments with Nicotiana benthamiana plants indicated that the soybean homolog GmPBS1-1 associated with AtRPS5 can perceive NopT. Further analysis showed that NopT cleaves AtPBS1 and GmPBS1-1 and thus can activate these target proteins. Insertion of a DKM motif at the cleavage site of GmPBS1-1 resulted in increased proteolysis. Nodulation tests with soybeans expressing an autoactive GmPBS1-1 variant indicated that activation of a GmPBS1-1-mediated resistance pathway impairs nodule formation in cv. Nenfeng 15. Our findings suggest that legumes face an evolutionary dilemma of either developing effector-triggered immunity against pathogenic bacteria or establishing symbiosis with suboptimally adapted rhizobia producing pathogen-like effectors.
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Affiliation(s)
- Asaf Khan
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, East Campus, 510006 Guangzhou, China
| | - Syed F Wadood
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, East Campus, 510006 Guangzhou, China
| | - Min Chen
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, East Campus, 510006 Guangzhou, China
| | - Yan Wang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, East Campus, 510006 Guangzhou, China
| | - Zhi-Ping Xie
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, East Campus, 510006 Guangzhou, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, East Campus, 510006 Guangzhou, China
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10
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Calla B. Friend or foe: How plants discriminate between pathogenic and mutualistic bacteria. PLANT PHYSIOLOGY 2022; 189:1893-1895. [PMID: 35608306 PMCID: PMC9342999 DOI: 10.1093/plphys/kiac238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
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11
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Li J, Zhang M, Zhou L. Protein S-acyltransferases and acyl protein thioesterases, regulation executors of protein S-acylation in plants. FRONTIERS IN PLANT SCIENCE 2022; 13:956231. [PMID: 35968095 PMCID: PMC9363829 DOI: 10.3389/fpls.2022.956231] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
Protein S-acylation, also known as palmitoylation, is an important lipid post-translational modification of proteins in eukaryotes. S-acylation plays critical roles in a variety of protein functions involved in plant development and responses to abiotic and biotic stresses. The status of S-acylation on proteins is dynamic and reversible, which is catalyzed by protein S-acyltransferases (PATs) and reversed by acyl protein thioesterases. The cycle of S-acylation and de-S-acylation provides a molecular mechanism for membrane-associated proteins to undergo cycling and trafficking between different cell compartments and thus works as a switch to initiate or terminate particular signaling transductions on the membrane surface. In plants, thousands of proteins have been identified to be S-acylated through proteomics. Many S-acylated proteins and quite a few PAT-substrate pairs have been functionally characterized. A recently characterized acyl protein thioesterases family, ABAPT family proteins in Arabidopsis, has provided new insights into the de-S-acylation process. However, our understanding of the regulatory mechanisms controlling the S-acylation and de-S-acylation process is surprisingly incomplete. In this review, we discuss how protein S-acylation level is regulated with the focus on catalyzing enzymes in plants. We also propose the challenges and potential developments for the understanding of the regulatory mechanisms controlling protein S-acylation in plants.
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Affiliation(s)
- Jincheng Li
- College of Forestry, Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Manqi Zhang
- College of Forestry, Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Lijuan Zhou
- College of Forestry, Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
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12
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Teulet A, Camuel A, Perret X, Giraud E. The Versatile Roles of Type III Secretion Systems in Rhizobia-Legume Symbioses. Annu Rev Microbiol 2022; 76:45-65. [PMID: 35395168 DOI: 10.1146/annurev-micro-041020-032624] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To suppress plant immunity and promote the intracellular infection required for fixing nitrogen for the benefit of their legume hosts, many rhizobia use type III secretion systems (T3SSs) that deliver effector proteins (T3Es) inside host cells. As reported for interactions between pathogens and host plants, the immune system of legume hosts and the cocktail of T3Es secreted by rhizobia determine the symbiotic outcome. If they remain undetected, T3Es may reduce plant immunity and thus promote infection of legumes by rhizobia. If one or more of the secreted T3Es are recognized by the cognate plant receptors, defense responses are triggered and rhizobial infection may abort. However, some rhizobial T3Es can also circumvent the need for nodulation (Nod) factors to trigger nodule formation. Here we review the multifaceted roles played by rhizobial T3Es during symbiotic interactions with legumes. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Albin Teulet
- Laboratoire des Symbioses Tropicales et Méditerranéennes (LSTM), IRD, Institut Agro, INRAE, Université de Montpellier, and CIRAD, Montpellier, France;
| | - Alicia Camuel
- Laboratoire des Symbioses Tropicales et Méditerranéennes (LSTM), IRD, Institut Agro, INRAE, Université de Montpellier, and CIRAD, Montpellier, France; .,PHIM Plant Health Institute, IRD, Institut Agro, INRAE, Université de Montpellier, and CIRAD, Montpellier, France
| | - Xavier Perret
- Laboratory of Microbial Genetics, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland
| | - Eric Giraud
- Laboratoire des Symbioses Tropicales et Méditerranéennes (LSTM), IRD, Institut Agro, INRAE, Université de Montpellier, and CIRAD, Montpellier, France; .,PHIM Plant Health Institute, IRD, Institut Agro, INRAE, Université de Montpellier, and CIRAD, Montpellier, France
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13
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Giglione C, Meinnel T. Mapping the myristoylome through a complete understanding of protein myristoylation biochemistry. Prog Lipid Res 2021; 85:101139. [PMID: 34793862 DOI: 10.1016/j.plipres.2021.101139] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 11/04/2021] [Accepted: 11/06/2021] [Indexed: 12/22/2022]
Abstract
Protein myristoylation is a C14 fatty acid modification found in all living organisms. Myristoylation tags either the N-terminal alpha groups of cysteine or glycine residues through amide bonds or lysine and cysteine side chains directly or indirectly via glycerol thioester and ester linkages. Before transfer to proteins, myristate must be activated into myristoyl coenzyme A in eukaryotes or, in bacteria, to derivatives like phosphatidylethanolamine. Myristate originates through de novo biosynthesis (e.g., plants), from external uptake (e.g., human tissues), or from mixed origins (e.g., unicellular organisms). Myristate usually serves as a molecular anchor, allowing tagged proteins to be targeted to membranes and travel across endomembrane networks in eukaryotes. In this review, we describe and discuss the metabolic origins of protein-bound myristate. We review strategies for in vivo protein labeling that take advantage of click-chemistry with reactive analogs, and we discuss new approaches to the proteome-wide discovery of myristate-containing proteins. The machineries of myristoylation are described, along with how protein targets can be generated directly from translating precursors or from processed proteins. Few myristoylation catalysts are currently described, with only N-myristoyltransferase described to date in eukaryotes. Finally, we describe how viruses and bacteria hijack and exploit myristoylation for their pathogenicity.
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Affiliation(s)
- Carmela Giglione
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - Thierry Meinnel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
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14
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Viana F, Peringathara SS, Rizvi A, Schroeder GN. Host manipulation by bacterial type III and type IV secretion system effector proteases. Cell Microbiol 2021; 23:e13384. [PMID: 34392594 DOI: 10.1111/cmi.13384] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 01/08/2023]
Abstract
Proteases are powerful enzymes, which cleave peptide bonds, leading most of the time to irreversible fragmentation or degradation of their substrates. Therefore they control many critical cell fate decisions in eukaryotes. Bacterial pathogens exploit this power and deliver protease effectors through specialised secretion systems into host cells. Research over the past years revealed that the functions of protease effectors during infection are diverse, reflecting the lifestyles and adaptations to specific hosts; however, only a small number of peptidase families seem to have given rise to most of these protease virulence factors by the evolution of different substrate-binding specificities, intracellular activation and subcellular targeting mechanisms. Here, we review our current knowledge about the enzymology and function of protease effectors, which Gram-negative bacterial pathogens translocate via type III and IV secretion systems to irreversibly manipulate host processes. We highlight emerging concepts such as signalling by protease cleavage products and effector-triggered immunity, which host cells employ to detect and defend themselves against a protease attack. TAKE AWAY: Proteases irreversibly cleave proteins to control critical cell fate decisions. Gram-negative bacteria use type III and IV secretion systems to inject effectors. Protease effectors are integral weapons for the manipulation of host processes. Effectors evolved from few peptidase families to target diverse substrates. Effector-triggered immunity upon proteolytic attack emerges as host defence.
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Affiliation(s)
- Flávia Viana
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Shruthi Sachidanandan Peringathara
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Arshad Rizvi
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Gunnar N Schroeder
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
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15
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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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16
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Schreiber KJ, Chau-Ly IJ, Lewis JD. What the Wild Things Do: Mechanisms of Plant Host Manipulation by Bacterial Type III-Secreted Effector Proteins. Microorganisms 2021; 9:1029. [PMID: 34064647 PMCID: PMC8150971 DOI: 10.3390/microorganisms9051029] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 01/05/2023] Open
Abstract
Phytopathogenic bacteria possess an arsenal of effector proteins that enable them to subvert host recognition and manipulate the host to promote pathogen fitness. The type III secretion system (T3SS) delivers type III-secreted effector proteins (T3SEs) from bacterial pathogens such as Pseudomonas syringae, Ralstonia solanacearum, and various Xanthomonas species. These T3SEs interact with and modify a range of intracellular host targets to alter their activity and thereby attenuate host immune signaling. Pathogens have evolved T3SEs with diverse biochemical activities, which can be difficult to predict in the absence of structural data. Interestingly, several T3SEs are activated following injection into the host cell. Here, we review T3SEs with documented enzymatic activities, as well as T3SEs that facilitate virulence-promoting processes either indirectly or through non-enzymatic mechanisms. We discuss the mechanisms by which T3SEs are activated in the cell, as well as how T3SEs modify host targets to promote virulence or trigger immunity. These mechanisms may suggest common enzymatic activities and convergent targets that could be manipulated to protect crop plants from infection.
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Affiliation(s)
- Karl J. Schreiber
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA; (K.J.S.); (I.J.C.-L.)
| | - Ilea J. Chau-Ly
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA; (K.J.S.); (I.J.C.-L.)
| | - Jennifer D. Lewis
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA; (K.J.S.); (I.J.C.-L.)
- Plant Gene Expression Center, United States Department of Agriculture, University of California, Berkeley, CA 94710, USA
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17
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Mooney BC, Mantz M, Graciet E, Huesgen PF. Cutting the line: manipulation of plant immunity by bacterial type III effector proteases. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3395-3409. [PMID: 33640987 DOI: 10.1093/jxb/erab095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Pathogens and their hosts are engaged in an evolutionary arms race. Pathogen-derived effectors promote virulence by targeting components of a host's innate immune system, while hosts have evolved proteins that sense effectors and trigger a pathogen-specific immune response. Many bacterial effectors are translocated into host cells using type III secretion systems. Type III effector proteases irreversibly modify host proteins by cleavage of peptide bonds and are prevalent among both plant and animal bacterial pathogens. In plants, the study of model effector proteases has yielded important insights into the virulence mechanisms employed by pathogens to overcome their host's immune response, as well as into the mechanisms deployed by their hosts to detect these effector proteases and counteract their effects. In recent years, the study of a larger number of effector proteases, across a wider range of pathogens, has yielded novel insights into their functions and recognition. One key limitation that remains is the lack of methods to detect protease cleavage at the proteome-wide level. We review known substrates and mechanisms of plant pathogen type III effector proteases and compare their functions with those of known type III effector proteases of mammalian pathogens. Finally, we discuss approaches to uncover their function on a system-wide level.
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Affiliation(s)
- Brian C Mooney
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - Melissa Mantz
- Central Institute for Engineering, Electronics and Analytics, ZEA-3, Forschungszentrum Jülich, Jülich, Germany
- CECAD, Medical Faculty and University Hospital, University of Cologne, Cologne, Germany
| | - Emmanuelle Graciet
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
- Kathleen Lonsdale Institute for Human Health Research, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Pitter F Huesgen
- Central Institute for Engineering, Electronics and Analytics, ZEA-3, Forschungszentrum Jülich, Jülich, Germany
- CECAD, Medical Faculty and University Hospital, University of Cologne, Cologne, Germany
- Institute for Biochemistry, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
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18
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Nucleotide-Binding Leucine-Rich Repeat Genes CsRSF1 and CsRSF2 Are Positive Modulators in the Cucumis sativus Defense Response to Sphaerotheca fuliginea. Int J Mol Sci 2021; 22:ijms22083986. [PMID: 33924330 PMCID: PMC8069588 DOI: 10.3390/ijms22083986] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 11/16/2022] Open
Abstract
Cucumber powdery mildew caused by Sphaerotheca fuliginea is a leaf disease that seriously affects cucumber's yield and quality. This study aimed to report two nucleotide-binding site-leucine-rich repeats (NBS-LRR) genes CsRSF1 and CsRSF2, which participated in regulating the resistance of cucumber to S. fuliginea. The subcellular localization showed that the CsRSF1 protein was localized in the nucleus, cytoplasm, and cell membrane, while the CsRSF2 protein was localized in the cell membrane and cytoplasm. In addition, the transcript levels of CsRSF1 and CsRSF2 were different between resistant and susceptible cultivars after treatment with exogenous substances, such as abscisic acid (ABA), methyl jasmonate (MeJA), salicylic acid (SA), ethephon (ETH), gibberellin (GA) and hydrogen peroxide (H2O2). The expression analysis showed that the transcript levels of CsRSF1 and CsRSF2 were correlated with plant defense response against S. fuliginea. Moreover, the silencing of CsRSF1 and CsRSF2 impaired host resistance to S. fuliginea, but CsRSF1 and CsRSF2 overexpression improved resistance to S. fuliginea in cucumber. These results showed that CsRSF1 and CsRSF2 genes positively contributed to the resistance of cucumber to S. fuliginea. At the same time, CsRSF1 and CsRSF2 genes could also regulate the expression of defense-related genes. The findings of this study might help enhance the resistance of cucumber to S. fuliginea.
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Luo Y, Liu D, Jiao S, Liu S, Wang X, Shen X, Wei G. Identification of Robinia pseudoacacia target proteins responsive to Mesorhizobium amphore CCNWGS0123 effector protein NopT. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:7347-7363. [PMID: 32865563 DOI: 10.1093/jxb/eraa405] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 08/28/2020] [Indexed: 06/11/2023]
Abstract
Nodulation outer proteins secreted via type 3 secretion systems are involved in the process of symbiosis between legume plants and rhizobia. To study the function of NopT in symbiosis, we mutated nopT in Mesorhizobium amphore CCNWGS0123 (GS0123), which can nodulate black locust (Robinia pseudoacacia). The nopT mutant induced higher levels of jasmonic acid, salicylic acid, and hydrogen peroxide accumulation in the roots of R. pseudoacacia compared with wild-type GS0123. The ΔnopT mutant induced higher disease-resistant gene expression 72 hours post-inoculation (hpi), whereas GS0123 induced higher disease-resistant gene expression earlier, at 36 hpi. Compared with the nopT mutant, GS0123 induced the up-regulation of most genes at 36 hpi and the down-regulation of most genes at 72 hpi. Proteolytically active NopT_GS0123 induced hypersensitive responses when expressed transiently in tobacco leaves (Nicotiana benthamiana). Two NopT_GS0123 targets in R. pseudoacacia were identified, ATP-citrate synthase alpha chain protein 2 and hypersensitive-induced response protein. Their interactions with NopT_GS0123 triggered resistance by the plant immune system. In conclusion, NopT_GS0123 inhibited the host plant immune system and had minimal effect on nodulation in R. pseudoacacia. Our results reveal the underlying molecular mechanism of NopT function in plant-symbiont interactions.
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Affiliation(s)
- Yantao Luo
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Dongying Liu
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Shuo Jiao
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Shuang Liu
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Xinye Wang
- Department of Liquor Making Engineering, Moutai College, Renhuai, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
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20
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Mei L, Qiu X, Jiang C, Yang A. Host Delipidation Mediated by Bacterial Effectors. Trends Microbiol 2020; 29:238-250. [PMID: 33092951 DOI: 10.1016/j.tim.2020.09.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/28/2020] [Accepted: 09/29/2020] [Indexed: 12/19/2022]
Abstract
Protein lipidation, the covalent attachment of a lipid moiety to a target protein, plays a critical role in many cellular processes in eukaryotic cells. Bacterial pathogens secrete various effectors to subvert the host signaling pathway as a mechanism of microbial pathogenesis. An increasing number of effectors from diverse bacterial pathogens function as cysteine proteases to cause irreversible delipidation of host lipidated proteins. This in turn results in disruption of crucial lipidation-mediated host signal transduction, thereby enabling pathogen survival and replication. In this review, we discuss the role of the bacterial effectors in interactions with the host and highlight our knowledge of irreversible host delipidation, with a focus on the common concerted biochemical mechanisms of the bacterial effectors.
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Affiliation(s)
- Ligang Mei
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Xiaofeng Qiu
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Chen Jiang
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing 401331, China; Ultrafast Transient Materials Science Center, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing 401331, China.
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21
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Hulin MT, Jackson RW, Harrison RJ, Mansfield JW. Cherry picking by pseudomonads: After a century of research on canker, genomics provides insights into the evolution of pathogenicity towards stone fruits. PLANT PATHOLOGY 2020; 69:962-978. [PMID: 32742023 PMCID: PMC7386918 DOI: 10.1111/ppa.13189] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/09/2020] [Accepted: 03/23/2020] [Indexed: 05/10/2023]
Abstract
Bacterial canker disease is a major limiting factor in the growing of cherry and other Prunus species worldwide. At least five distinct clades within the bacterial species complex Pseudomonas syringae are known to be causal agents of the disease. The different pathogens commonly coexist in the field. Reducing canker is a challenging prospect as the efficacy of chemical controls and host resistance may vary against each of the diverse clades involved. Genomic analysis has revealed that the pathogens use a variable repertoire of virulence factors to cause the disease. Significantly, strains of P. syringae pv. syringae possess more genes for toxin biosynthesis and fewer encoding type III effector proteins. There is also a shared pool of key effector genes present on mobile elements such as plasmids and prophages that may have roles in virulence. By contrast, there is evidence that absence or truncation of certain effector genes, such as hopAB, is characteristic of cherry pathogens. Here we highlight how recent research, underpinned by the earlier epidemiological studies, is allowing significant progress in our understanding of the canker pathogens. This fundamental knowledge, combined with emerging insights into host genetics, provides the groundwork for development of precise control measures and informed approaches to breed for disease resistance.
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Affiliation(s)
| | - Robert W. Jackson
- Birmingham Institute of Forest Research (BIFoR), University of BirminghamBirminghamUK
- School of Biosciences, University of BirminghamBirminghamUK
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22
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Pottinger SE, Bak A, Margets A, Helm M, Tang L, Casteel C, Innes RW. Optimizing the PBS1 Decoy System to Confer Resistance to Potyvirus Infection in Arabidopsis and Soybean. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:932-944. [PMID: 32267815 DOI: 10.1094/mpmi-07-19-0190-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The Arabidopsis resistance protein RPS5 is activated by proteolytic cleavage of the protein kinase PBS1 by the Pseudomonas syringae effector protease AvrPphB. We have previously shown that replacing seven amino acids at the cleavage site of PBS1 with a motif cleaved by the NIa protease of turnip mosaic virus (TuMV) enables RPS5 activation upon TuMV infection. However, this engineered resistance conferred a trailing necrosis phenotype indicative of a cell-death response too slow to contain the virus. We theorized this could result from a positional mismatch within the cell between PBS1TuMV, RPS5, and the NIa protease. To test this, we relocalized PBS1TuMV and RPS5 to cellular sites of NIa accumulation. These experiments revealed that relocation of RPS5 away from the plasma membrane compromised RPS5-dependent cell death in Nicotiana benthamiana, even though PBS1 was efficiently cleaved. As an alternative approach, we tested whether overexpression of plasma membrane-localized PBS1TuMV could enhance RPS5 activation by TuMV. Significantly, overexpressing the PBS1TuMV decoy protein conferred complete resistance to TuMV when delivered by either agrobacterium or by aphid transmission, showing that RPS5-mediated defense responses are effective against bacterial and viral pathogens. Lastly, we have now extended this PBS1 decoy approach to soybean by modifying a soybean PBS1 ortholog to be cleaved by the NIa protease of soybean mosaic virus (SMV). Transgenic overexpression of this soybean PBS1 decoy conferred immunity to SMV, demonstrating that we can use endogenous PBS1 proteins in crop plants to engineer economically relevant disease resistant traits.
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Affiliation(s)
- Sarah E Pottinger
- Indiana University, Department of Biology, Bloomington, IN 47405, U.S.A
| | - Aurelie Bak
- University of California, Department of Plant Pathology, Davis, CA 95616, U.S.A
| | - Alexandra Margets
- Indiana University, Department of Biology, Bloomington, IN 47405, U.S.A
| | - Matthew Helm
- Indiana University, Department of Biology, Bloomington, IN 47405, U.S.A
- United States Department of Agriculture, Agricultural Research Service, Crop Production and Pest Control Research Unit, West Lafayette, IN 47907, U.S.A
| | - Lucas Tang
- Indiana University, Department of Biology, Bloomington, IN 47405, U.S.A
| | - Clare Casteel
- University of California, Department of Plant Pathology, Davis, CA 95616, U.S.A
| | - Roger W Innes
- Indiana University, Department of Biology, Bloomington, IN 47405, U.S.A
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23
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Zhang Q, Li W, Yang J, Xu J, Meng Y, Shan W. Two Phytophthora parasitica cysteine protease genes, PpCys44 and PpCys45, trigger cell death in various Nicotiana spp. and act as virulence factors. MOLECULAR PLANT PATHOLOGY 2020; 21:541-554. [PMID: 32077241 PMCID: PMC7060141 DOI: 10.1111/mpp.12915] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 01/12/2020] [Accepted: 01/13/2020] [Indexed: 05/19/2023]
Abstract
Proteases secreted by pathogens have been shown to be important virulence factors modifying plant immunity, and cysteine proteases have been demonstrated to participate in different pathosystems. However, the virulence functions of the cysteine proteases secreted by Phytophthora parasitica are poorly understood. Using a publicly available genome database, we identified 80 cysteine proteases in P. parasitica, 21 of which were shown to be secreted. Most of the secreted cysteine proteases are conserved among different P. parasitica strains and are induced during infection. The secreted cysteine protease proteins PpCys44/45 (proteases with identical protein sequences) and PpCys69 triggered cell death on the leaves of different Nicotiana spp. A truncated mutant of PpCys44/45 lacking a signal peptide failed to trigger cell death, suggesting that PpCys44/45 functions in the apoplastic space. Analysis of three catalytic site mutants showed that the enzyme activity of PpCys44/45 is required for its ability to trigger cell death. A virus-induced gene silencing assay showed that PpCys44/45 does not induce cell death on NPK1 (Nicotiana Protein Kinase 1)-silenced Nicotiana benthamiana plants, indicating that the cell death phenotype triggered by PpCys44/45 is dependent on NPK1. PpCys44- and PpCys45-deficient double mutants showed decreased virulence, suggesting that PpCys44 and PpCys45 positively promote pathogen virulence during infection. PpCys44 and PpCys45 are important virulence factors of P. parasitica and trigger NPK1-dependent cell death in various Nicotiana spp.
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Affiliation(s)
- Qiang Zhang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingChina
- College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Weiwei Li
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingChina
- College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Jiapeng Yang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingChina
- College of AgronomyNorthwest A&F UniversityYanglingChina
| | - Junjie Xu
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingChina
- College of Plant ProtectionNorthwest A&F UniversityYanglingChina
| | - Yuling Meng
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingChina
- College of AgronomyNorthwest A&F UniversityYanglingChina
| | - Weixing Shan
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingChina
- College of AgronomyNorthwest A&F UniversityYanglingChina
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24
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Xiang QW, Bai J, Cai J, Huang QY, Wang Y, Liang Y, Zhong Z, Wagner C, Xie ZP, Staehelin C. NopD of Bradyrhizobium sp. XS1150 Possesses SUMO Protease Activity. Front Microbiol 2020; 11:386. [PMID: 32265858 PMCID: PMC7098955 DOI: 10.3389/fmicb.2020.00386] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 02/21/2020] [Indexed: 01/19/2023] Open
Abstract
Effectors secreted by the type III protein secretion system (T3SS) of rhizobia are host-specific determinants of the nodule symbiosis. Here, we have characterized NopD, a putative type III effector of Bradyrhizobium sp. XS1150. NopD was found to possess a functional N-terminal secretion signal sequence that could replace that of the NopL effector secreted by Sinorhizobium sp. NGR234. Recombinant NopD and the C-terminal domain of NopD alone can process small ubiquitin-related modifier (SUMO) proteins and cleave SUMO-conjugated proteins. Activity was abolished in a NopD variant with a cysteine-to-alanine substitution in the catalytic core (NopD-C972A). NopD recognizes specific plant SUMO proteins (AtSUMO1 and AtSUMO2 of Arabidopsis thaliana; GmSUMO of Glycine max; PvSUMO of Phaseolus vulgaris). Subcellular localization analysis with A. thaliana protoplasts showed that NopD accumulates in nuclear bodies. NopD, but not NopD-C972A, induces cell death when expressed in Nicotiana tabacum. Likewise, inoculation tests with constructed mutant strains of XS1150 indicated that nodulation of Tephrosia vogelii is negatively affected by the protease activity of NopD. In conclusion, our findings show that NopD is a symbiosis-related protein that can process specific SUMO proteins and desumoylate SUMO-conjugated proteins.
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Affiliation(s)
- Qi-Wang Xiang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Juan Bai
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jie Cai
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qin-Ying Huang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yan Wang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ying Liang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhi Zhong
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Christian Wagner
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhi-Ping Xie
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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Carter ME, Helm M, Chapman AVE, Wan E, Restrepo Sierra AM, Innes RW, Bogdanove AJ, Wise RP. Convergent Evolution of Effector Protease Recognition by Arabidopsis and Barley. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:550-565. [PMID: 30480480 DOI: 10.1094/mpmi-07-18-0202-fi] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Pseudomonas syringae cysteine protease AvrPphB activates the Arabidopsis resistance protein RPS5 by cleaving a second host protein, PBS1. AvrPphB induces defense responses in other plant species, but the genes and mechanisms mediating AvrPphB recognition in those species have not been defined. Here, we show that AvrPphB induces defense responses in diverse barley cultivars. We also show that barley contains two PBS1 orthologs, that their products are cleaved by AvrPphB, and that the barley AvrPphB response maps to a single locus containing a nucleotide-binding leucine-rich repeat (NLR) gene, which we termed AvrPphB Response 1 (Pbr1). Transient coexpression of PBR1 with wild-type AvrPphB but not with a protease inactive mutant triggered defense responses, indicating that PBR1 detects AvrPphB protease activity. Additionally, PBR1 coimmunoprecipitated with barley and Nicotiana benthamiana PBS1 proteins, suggesting mechanistic similarity to detection by RPS5. Lastly, we determined that wheat cultivars also recognize AvrPphB protease activity and contain two putative Pbr1 orthologs. Phylogenetic analyses showed, however, that Pbr1 is not orthologous to RPS5. Our results indicate that the ability to recognize AvrPphB evolved convergently and imply that selection to guard PBS1-like proteins occurs across species. Also, these results suggest that PBS1-based decoys may be used to engineer protease effector recognition-based resistance in barley and wheat.
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Affiliation(s)
- Morgan E Carter
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Matthew Helm
- 2 Department of Biology, Indiana University, Bloomington, IN, U.S.A
| | - Antony V E Chapman
- 3 Interdepartmental Genetics & Genomics Graduate Program and
- 4 Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA, U.S.A
| | - Emily Wan
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Ana Maria Restrepo Sierra
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
- 5 Facultad de Ciencias, Universidad Nacional de Colombia Sede Medellín, Medellín, Colombia; and
| | - Roger W Innes
- 2 Department of Biology, Indiana University, Bloomington, IN, U.S.A
| | - Adam J Bogdanove
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Roger P Wise
- 3 Interdepartmental Genetics & Genomics Graduate Program and
- 4 Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA, U.S.A
- 6 Corn Insects and Crop Genetics Research, USDA-Agricultural Research Service, Ames, IA, U.S.A
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Rao W, Zheng X, Liu B, Guo Q, Guo J, Wu Y, Shangguan X, Wang H, Wu D, Wang Z, Hu L, Xu C, Jiang W, Huang J, Shi S, He G. Secretome Analysis and In Planta Expression of Salivary Proteins Identify Candidate Effectors from the Brown Planthopper Nilaparvata lugens. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:227-239. [PMID: 30168780 DOI: 10.1094/mpmi-05-18-0122-r] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The brown planthopper (BPH), Nilaparvata lugens (Stål), is a phloem sap-feeding insect. During feeding on rice plants, BPH secretes salivary proteins with potential effector functions, which may play a critical role in the plant-insect interactions. However, a limited number of BPH effector proteins have been identified to date. Here, we sequenced the salivary gland transcriptomes of five BPH populations and subsequently established a N. lugens secretome consisting of 1,140 protein-encoding genes. Secretome analysis revealed the presence of both conserved and rapidly evolving salivary proteins. A screen for potential effectors that elicit responses in the plant was performed via the transient expression analysis of 64 BPH salivary proteins in Nicotiana benthamiana leaves and rice protoplasts. The salivary proteins Nl12, Nl16, Nl28, and Nl43 induced cell death, whereas Nl40 induced chlorosis and Nl32 induced a dwarf phenotype in N. benthamiana, indicating effector properties of these proteins. Ectopic expression of the six salivary proteins in N. benthamiana upregulated expression of defense-related genes and callose deposition. Tissue expression analysis showed a higher expression level of the six candidate effectors in salivary glands than in other tissues. Subcellular localization and analysis of the domain required for cell death showed a diverse structure of the six effectors. Nl28, Nl40, and Nl43 are N. lugens specific; in contrast, Nl12, Nl16, and Nl32 are conserved among insects. The Nl40 family has numerous isoforms produced by alternative splicing, exemplifying rapid evolution and expansion of effector proteins in the BPH. Our results suggest a potential large effector repertoire in BPH and a higher level of effector conservation exist in BPH compared with that in plant pathogens.
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Affiliation(s)
- Weiwei Rao
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Xiaohong Zheng
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Bingfang Liu
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Qin Guo
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Jianping Guo
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Yan Wu
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Xinxin Shangguan
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Huiying Wang
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Di Wu
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Zhizheng Wang
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Liang Hu
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Chunxue Xu
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Weihua Jiang
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Jin Huang
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Shaojie Shi
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
| | - Guangcun He
- National Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, China
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27
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Lu Y, Yao J. Chloroplasts at the Crossroad of Photosynthesis, Pathogen Infection and Plant Defense. Int J Mol Sci 2018; 19:E3900. [PMID: 30563149 PMCID: PMC6321325 DOI: 10.3390/ijms19123900] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 12/31/2022] Open
Abstract
Photosynthesis, pathogen infection, and plant defense are three important biological processes that have been investigated separately for decades. Photosynthesis generates ATP, NADPH, and carbohydrates. These resources are utilized for the synthesis of many important compounds, such as primary metabolites, defense-related hormones abscisic acid, ethylene, jasmonic acid, and salicylic acid, and antimicrobial compounds. In plants and algae, photosynthesis and key steps in the synthesis of defense-related hormones occur in chloroplasts. In addition, chloroplasts are major generators of reactive oxygen species and nitric oxide, and a site for calcium signaling. These signaling molecules are essential to plant defense as well. All plants grown naturally are attacked by pathogens. Bacterial pathogens enter host tissues through natural openings or wounds. Upon invasion, bacterial pathogens utilize a combination of different virulence factors to suppress host defense and promote pathogenicity. On the other hand, plants have developed elaborate defense mechanisms to protect themselves from pathogen infections. This review summarizes recent discoveries on defensive roles of signaling molecules made by plants (primarily in their chloroplasts), counteracting roles of chloroplast-targeted effectors and phytotoxins elicited by bacterial pathogens, and how all these molecules crosstalk and regulate photosynthesis, pathogen infection, and plant defense, using chloroplasts as a major battlefield.
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Affiliation(s)
- Yan Lu
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008, USA.
| | - Jian Yao
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008, USA.
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28
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Gregor R, David S, Meijler MM. Chemical strategies to unravel bacterial-eukaryotic signaling. Chem Soc Rev 2018; 47:1761-1772. [PMID: 29260158 DOI: 10.1039/c7cs00606c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The common language of bacteria and higher life forms is a lexicon of small molecules that the research community is only beginning to decipher. While many new signaling molecules have been discovered in recent years, the identification of their targets is mostly lagging. This review will focus on the latest chemical-probe based research aimed at understanding how bacteria interact chemically with mammals and plants. In general, chemical biology strategies remain under-utilized in this complex field of research, with a few key exceptions, and we hope that this review encourages others to implement these techniques in their research. Specifically, we highlight the chemical biology techniques used in recent studies, especially activity-based protein profiling, that have been applied to unravel the chemical mechanisms of interkingdom interactions.
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Affiliation(s)
- R Gregor
- Department of Chemistry and National Institute of Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, 84105, Israel.
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Sobocińska J, Roszczenko-Jasińska P, Ciesielska A, Kwiatkowska K. Protein Palmitoylation and Its Role in Bacterial and Viral Infections. Front Immunol 2018; 8:2003. [PMID: 29403483 PMCID: PMC5780409 DOI: 10.3389/fimmu.2017.02003] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/26/2017] [Indexed: 12/11/2022] Open
Abstract
S-palmitoylation is a reversible, enzymatic posttranslational modification of proteins in which palmitoyl chain is attached to a cysteine residue via a thioester linkage. S-palmitoylation determines the functioning of proteins by affecting their association with membranes, compartmentalization in membrane domains, trafficking, and stability. In this review, we focus on S-palmitoylation of proteins, which are crucial for the interactions of pathogenic bacteria and viruses with the host. We discuss the role of palmitoylated proteins in the invasion of host cells by bacteria and viruses, and those involved in the host responses to the infection. We highlight recent data on protein S-palmitoylation in pathogens and their hosts obtained owing to the development of methods based on click chemistry and acyl-biotin exchange allowing proteomic analysis of protein lipidation. The role of the palmitoyl moiety present in bacterial lipopolysaccharide and lipoproteins, contributing to infectivity and affecting recognition of bacteria by innate immune receptors, is also discussed.
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Affiliation(s)
- Justyna Sobocińska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
| | - Paula Roszczenko-Jasińska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
| | - Anna Ciesielska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
| | - Katarzyna Kwiatkowska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
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30
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Büttner D. Behind the lines-actions of bacterial type III effector proteins in plant cells. FEMS Microbiol Rev 2018; 40:894-937. [PMID: 28201715 PMCID: PMC5091034 DOI: 10.1093/femsre/fuw026] [Citation(s) in RCA: 181] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/31/2016] [Accepted: 07/03/2016] [Indexed: 01/30/2023] Open
Abstract
Pathogenicity of most Gram-negative plant-pathogenic bacteria depends on the type III secretion (T3S) system, which translocates bacterial effector proteins into plant cells. Type III effectors modulate plant cellular pathways to the benefit of the pathogen and promote bacterial multiplication. One major virulence function of type III effectors is the suppression of plant innate immunity, which is triggered upon recognition of pathogen-derived molecular patterns by plant receptor proteins. Type III effectors also interfere with additional plant cellular processes including proteasome-dependent protein degradation, phytohormone signaling, the formation of the cytoskeleton, vesicle transport and gene expression. This review summarizes our current knowledge on the molecular functions of type III effector proteins with known plant target molecules. Furthermore, plant defense strategies for the detection of effector protein activities or effector-triggered alterations in plant targets are discussed.
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Affiliation(s)
- Daniela Büttner
- Genetics Department, Institute of Biology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
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31
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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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32
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Li Y, Qi B. Progress toward Understanding Protein S-acylation: Prospective in Plants. FRONTIERS IN PLANT SCIENCE 2017; 8:346. [PMID: 28392791 PMCID: PMC5364179 DOI: 10.3389/fpls.2017.00346] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 02/28/2017] [Indexed: 05/02/2023]
Abstract
S-acylation, also known as S-palmitoylation or palmitoylation, is a reversible post-translational lipid modification in which long chain fatty acid, usually the 16-carbon palmitate, covalently attaches to a cysteine residue(s) throughout the protein via a thioester bond. It is involved in an array of important biological processes during growth and development, reproduction and stress responses in plant. S-acylation is a ubiquitous mechanism in eukaryotes catalyzed by a family of enzymes called Protein S-Acyl Transferases (PATs). Since the discovery of the first PAT in yeast in 2002 research in S-acylation has accelerated in the mammalian system and followed by in plant. However, it is still a difficult field to study due to the large number of PATs and even larger number of putative S-acylated substrate proteins they modify in each genome. This is coupled with drawbacks in the techniques used to study S-acylation, leading to the slower progress in this field compared to protein phosphorylation, for example. In this review we will summarize the discoveries made so far based on knowledge learnt from the characterization of protein S-acyltransferases and the S-acylated proteins, the interaction mechanisms between PAT and its specific substrate protein(s) in yeast and mammals. Research in protein S-acylation and PATs in plants will also be covered although this area is currently less well studied in yeast and mammalian systems.
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33
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Schreiber KJ, Baudin M, Hassan JA, Lewis JD. Die another day: Molecular mechanisms of effector-triggered immunity elicited by type III secreted effector proteins. Semin Cell Dev Biol 2016; 56:124-133. [DOI: 10.1016/j.semcdb.2016.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 05/02/2016] [Indexed: 11/27/2022]
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34
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Popa CM, Tabuchi M, Valls M. Modification of Bacterial Effector Proteins Inside Eukaryotic Host Cells. Front Cell Infect Microbiol 2016; 6:73. [PMID: 27489796 PMCID: PMC4951486 DOI: 10.3389/fcimb.2016.00073] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 06/27/2016] [Indexed: 12/16/2022] Open
Abstract
Pathogenic bacteria manipulate their hosts by delivering a number of virulence proteins -called effectors- directly into the plant or animal cells. Recent findings have shown that such effectors can suffer covalent modifications inside the eukaryotic cells. Here, we summarize the recent reports where effector modifications by the eukaryotic machinery have been described. We restrict our focus on proteins secreted by the type III or type IV systems, excluding other bacterial toxins. We describe the known examples of effectors whose enzymatic activity is triggered by interaction with plant and animal cell factors, including GTPases, E2-Ubiquitin conjugates, cyclophilin and thioredoxins. We focus on the structural interactions with these factors and their influence on effector function. We also review the described examples of host-mediated post-translational effector modifications which are required for proper subcellular location and function. These host-specific covalent modifications include phosphorylation, ubiquitination, SUMOylation, and lipidations such as prenylation, fatty acylation and phospholipid binding.
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Affiliation(s)
- Crina M Popa
- Department of Genetics, Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB), Universitat de Barcelona Barcelona, Spain
| | - Mitsuaki Tabuchi
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University Kagawa, Japan
| | - Marc Valls
- Department of Genetics, Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB), Universitat de Barcelona Barcelona, Spain
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35
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Washington EJ, Mukhtar MS, Finkel OM, Wan L, Banfield MJ, Kieber JJ, Dangl JL. Pseudomonas syringae type III effector HopAF1 suppresses plant immunity by targeting methionine recycling to block ethylene induction. Proc Natl Acad Sci U S A 2016; 113:E3577-86. [PMID: 27274076 PMCID: PMC4922156 DOI: 10.1073/pnas.1606322113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
HopAF1 is a type III effector protein of unknown function encoded in the genomes of several strains of Pseudomonas syringae and other plant pathogens. Structural modeling predicted that HopAF1 is closely related to deamidase proteins. Deamidation is the irreversible substitution of an amide group with a carboxylate group. Several bacterial virulence factors are deamidases that manipulate the activity of specific host protein substrates. We identified Arabidopsis methylthioadenosine nucleosidase proteins MTN1 and MTN2 as putative targets of HopAF1 deamidation. MTNs are enzymes in the Yang cycle, which is essential for the high levels of ethylene biosynthesis in Arabidopsis We hypothesized that HopAF1 inhibits the host defense response by manipulating MTN activity and consequently ethylene levels. We determined that bacterially delivered HopAF1 inhibits ethylene biosynthesis induced by pathogen-associated molecular patterns and that Arabidopsis mtn1 mtn2 mutant plants phenocopy the effect of HopAF1. Furthermore, we identified two conserved asparagines in MTN1 and MTN2 from Arabidopsis that confer loss of function phenotypes when deamidated via site-specific mutation. These residues are potential targets of HopAF1 deamidation. HopAF1-mediated manipulation of Yang cycle MTN proteins is likely an evolutionarily conserved mechanism whereby HopAF1 orthologs from multiple plant pathogens contribute to disease in a large variety of plant hosts.
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Affiliation(s)
- Erica J Washington
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - M Shahid Mukhtar
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Omri M Finkel
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Li Wan
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Mark J Banfield
- Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH, United Kingdom
| | - Joseph J Kieber
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Jeffery L Dangl
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599; Howard Hughes Medical Institute, University of North Carolina, Chapel Hill, NC 27599; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599; Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599; Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC 27599
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36
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Xiang J, Li X, Wu J, Yin L, Zhang Y, Lu J. Studying the Mechanism of Plasmopara viticola RxLR Effectors on Suppressing Plant Immunity. Front Microbiol 2016; 7:709. [PMID: 27242731 PMCID: PMC4870276 DOI: 10.3389/fmicb.2016.00709] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/28/2016] [Indexed: 01/02/2023] Open
Abstract
The RxLR effector family, produced by oomycete pathogens, may manipulate host physiological and biochemical events inside host cells. A group of putative RxLR effectors from Plasmopara viticola have been recently identified by RNA-Seq analysis in our lab. However, their roles in pathogenesis are poorly understood. In this study, we attempted to characterize 23 PvRxLR effector candidates identified from a P. viticola isolate “ZJ-1-1.” During host infection stages, expression patterns of the effector genes were varied and could be categorized into four different groups. By using transient expression assays in Nicotiana benthamiana, we found that 17 of these effector candidates fully suppressed programmed cell death elicited by a range of cell death-inducing proteins, including BAX, INF1, PsCRN63, PsojNIP, PvRxLR16 and R3a/Avr3a. We also discovered that all these PvRxLRs could target the plant cell nucleus, except for PvRxLR55 that localized to the membrane. Furthermore, we identified a single effector, PvRxLR28, that showed the highest expression level at 6 hpi. Functional analysis revealed that PvRxLR28 could significantly enhance susceptibilities of grapevine and tobacco to pathogens. These results suggest that most P. viticola effectors tested in this study may act as broad suppressors of cell death to manipulate immunity in plant.
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Affiliation(s)
- Jiang Xiang
- The Viticulture and Enology Program, College of Food Science and Nutritional Engineering, China Agricultural University Beijing, China
| | - Xinlong Li
- The Viticulture and Enology Program, College of Food Science and Nutritional Engineering, China Agricultural University Beijing, China
| | - Jiao Wu
- The Viticulture and Enology Program, College of Food Science and Nutritional Engineering, China Agricultural University Beijing, China
| | - Ling Yin
- Guangxi Crop Genetic Improvement and Biotechnology Laboratory, Guangxi Academy of Agricultural Sciences Nanning, China
| | - Yali Zhang
- The Viticulture and Enology Program, College of Food Science and Nutritional Engineering, China Agricultural University Beijing, China
| | - Jiang Lu
- The Viticulture and Enology Program, College of Food Science and Nutritional Engineering, China Agricultural University Beijing, China
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37
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Kim BS, Satchell KJF. MARTX effector cross kingdom activation by Golgi-associated ADP-ribosylation factors. Cell Microbiol 2016; 18:1078-93. [PMID: 26780191 DOI: 10.1111/cmi.12568] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/28/2015] [Accepted: 01/10/2016] [Indexed: 02/07/2023]
Abstract
Vibrio vulnificus infects humans and causes lethal septicemia. The primary virulence factor is a multifunctional-autoprocessing repeats-in-toxin (MARTX) toxin consisting of conserved repeats-containing regions and various effector domains. Recent genomic analyses for the newly emerged V. vulnificus biotype 3 strain revealed that its MARTX toxin has two previously unknown effector domains. Herein, we characterized one of these domains, Domain X (DmXVv ). A structure-based homology search revealed that DmXVv belongs to the C58B cysteine peptidase subfamily. When ectopically expressed in cells, DmXVv was autoprocessed and induced cytopathicity including Golgi dispersion. When the catalytic cysteine or the region flanking the scissile bond was mutated, both autoprocessing and cytopathicity were significantly reduced indicating that DmXVv cytopathicity is activated by amino-terminal autoprocessing. Consistent with this, host cell protein export was affected by Vibrio cells producing a toxin with wild-type, but not catalytically inactive, DmXVv . DmXVv was found to localize to Golgi and to directly interact with Golgi-associated ADP-ribosylation factors ARF1, ARF3 and ARF4, although ARF binding was not necessary for the subcellular localization. Rather, this interaction was found to induce autoprocessing of DmXVv . These data demonstrate that the V. vulnificus hijacks the host ARF proteins to activate the cytopathic DmXVv effector domain of MARTX toxin.
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Affiliation(s)
- Byoung Sik Kim
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Karla J F Satchell
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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Boyle PC, Schwizer S, Hind SR, Kraus CM, De la Torre Diaz S, He B, Martin GB. Detecting N-myristoylation and S-acylation of host and pathogen proteins in plants using click chemistry. PLANT METHODS 2016; 12:38. [PMID: 27493678 PMCID: PMC4972946 DOI: 10.1186/s13007-016-0138-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 07/20/2016] [Indexed: 05/06/2023]
Abstract
BACKGROUND The plant plasma membrane is a key battleground in the war between plants and their pathogens. Plants detect the presence of pathogens at the plasma membrane using sensor proteins, many of which are targeted to this lipophilic locale by way of fatty acid modifications. Pathogens secrete effector proteins into the plant cell to suppress the plant's defense mechanisms. These effectors are able to access and interfere with the surveillance machinery at the plant plasma membrane by hijacking the host's fatty acylation apparatus. Despite the important involvement of protein fatty acylation in both plant immunity and pathogen virulence mechanisms, relatively little is known about the role of this modification during plant-pathogen interactions. This dearth in our understanding is due largely to the lack of methods to monitor protein fatty acid modifications in the plant cell. RESULTS We describe a rapid method to detect two major forms of fatty acylation, N-myristoylation and S-acylation, of candidate proteins using alkyne fatty acid analogs coupled with click chemistry. We applied our approach to confirm and decisively demonstrate that the archetypal pattern recognition receptor FLS2, the well-characterized pathogen effector AvrPto, and one of the best-studied intracellular resistance proteins, Pto, all undergo plant-mediated fatty acylation. In addition to providing a means to readily determine fatty acylation, particularly myristoylation, of candidate proteins, this method is amenable to a variety of expression systems. We demonstrate this using both Arabidopsis protoplasts and stable transgenic Arabidopsis plants and we leverage Agrobacterium-mediated transient expression in Nicotiana benthamiana leaves as a means for high-throughput evaluation of candidate proteins. CONCLUSIONS Protein fatty acylation is a targeting tactic employed by both plants and their pathogens. The metabolic labeling approach leveraging alkyne fatty acid analogs and click chemistry described here has the potential to provide mechanistic details of the molecular tactics used at the host plasma membrane in the battle between plants and pathogens.
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Affiliation(s)
- Patrick C. Boyle
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Monsanto Company, St. Louis, MO 63141 USA
| | - Simon Schwizer
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Plant Pathology and Plant–Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853 USA
| | - Sarah R. Hind
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
| | - Christine M. Kraus
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Plant Pathology and Plant–Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853 USA
| | | | - Bin He
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 USA
- College of Pharmacy, Guiyang Medical University, Guiyang, 550004 Guizhou China
| | - Gregory B. Martin
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853 USA
- Plant Pathology and Plant–Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853 USA
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Abstract
Rhizobia are nitrogen-fixing bacteria that establish a nodule symbiosis with legumes. Nodule formation depends on signals and surface determinants produced by both symbiotic partners. Among them, rhizobial Nops (nodulation outer proteins) play a crucial symbiotic role in many strain-host combinations. Nops are defined as proteins secreted via a rhizobial T3SS (type III secretion system). Functional T3SSs have been characterized in many rhizobial strains. Nops have been identified using various genetic, biochemical, proteomic, genomic and experimental approaches. Certain Nops represent extracellular components of the T3SS, which are visible in electron micrographs as bacterial surface appendages called T3 (type III) pili. Other Nops are T3 effector proteins that can be translocated into plant cells. Rhizobial T3 effectors manipulate cellular processes in host cells to suppress plant defence responses against rhizobia and to promote symbiosis-related processes. Accordingly, mutant strains deficient in synthesis or secretion of T3 effectors show reduced symbiotic properties on certain host plants. On the other hand, direct or indirect recognition of T3 effectors by plant cells expressing specific R (resistance) proteins can result in effector triggered defence responses that negatively affect rhizobial infection. Hence Nops are double-edged swords that may promote establishment of symbiosis with one legume (symbiotic factors) and impair symbiotic processes when bacteria are inoculated on another legume species (asymbiotic factors). In the present review, we provide an overview of our current understanding of Nops. We summarize their symbiotic effects, their biochemical properties and their possible modes of action. Finally, we discuss future perspectives in the field of T3 effector research.
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Lin YH, Doms AG, Cheng E, Kim B, Evans TR, Machner MP. Host Cell-catalyzed S-Palmitoylation Mediates Golgi Targeting of the Legionella Ubiquitin Ligase GobX. J Biol Chem 2015; 290:25766-81. [PMID: 26316537 DOI: 10.1074/jbc.m115.637397] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Indexed: 01/10/2023] Open
Abstract
The facultative intracellular pathogen Legionella pneumophila, the causative agent of Legionnaires disease, infects and replicates within human alveolar macrophages. L. pneumophila delivers almost 300 effector proteins into the besieged host cell that alter signaling cascades and create conditions that favor intracellular bacterial survival. In order for the effectors to accomplish their intracellular mission, their activity needs to be specifically directed toward the correct host cell protein or target organelle. Here, we show that the L. pneumophila effector GobX possesses E3 ubiquitin ligase activity that is mediated by a central region homologous to mammalian U-box domains. Furthermore, we demonstrate that GobX exploits host cell S-palmitoylation to specifically localize to Golgi membranes. The hydrophobic palmitate moiety is covalently attached to a cysteine residue at position 175, which is part of an amphipathic α-helix within the C-terminal region of GobX. Site-directed mutagenesis of cysteine 175 or residues on the hydrophobic face of the amphipathic helix strongly attenuated palmitoylation and Golgi localization of GobX. Together, our study provides evidence that the L. pneumophila effector GobX exploits two post-translational modification pathways of host cells, ubiquitination and S-palmitoylation.
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Affiliation(s)
- Yi-Han Lin
- From the Unit on Microbial Pathogenesis, Cell Biology and Metabolism Program, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Alexandra G Doms
- From the Unit on Microbial Pathogenesis, Cell Biology and Metabolism Program, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Eric Cheng
- From the Unit on Microbial Pathogenesis, Cell Biology and Metabolism Program, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Byoungkwan Kim
- From the Unit on Microbial Pathogenesis, Cell Biology and Metabolism Program, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Timothy R Evans
- From the Unit on Microbial Pathogenesis, Cell Biology and Metabolism Program, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Matthias P Machner
- From the Unit on Microbial Pathogenesis, Cell Biology and Metabolism Program, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
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Gonzalez TL, Liang Y, Nguyen BN, Staskawicz BJ, Loqué D, Hammond MC. Tight regulation of plant immune responses by combining promoter and suicide exon elements. Nucleic Acids Res 2015; 43:7152-61. [PMID: 26138488 PMCID: PMC4538838 DOI: 10.1093/nar/gkv655] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/12/2015] [Accepted: 06/16/2015] [Indexed: 11/20/2022] Open
Abstract
Effector-triggered immunity (ETI) is activated when plant disease resistance (R) proteins recognize the presence of pathogen effector proteins delivered into host cells. The ETI response generally encompasses a defensive 'hypersensitive response' (HR) that involves programmed cell death at the site of pathogen recognition. While many R protein and effector protein pairs are known to trigger HR, other components of the ETI signaling pathway remain elusive. Effector genes regulated by inducible promoters cause background HR due to leaky protein expression, preventing the generation of relevant transgenic plant lines. By employing the HyP5SM suicide exon, we have developed a strategy to tightly regulate effector proteins such that HR is chemically inducible and non-leaky. This alternative splicing-based gene regulation system was shown to successfully control Bs2/AvrBs2-dependent and RPP1/ATR1Δ51-dependent HR in Nicotiana benthamiana and Nicotiana tabacum, respectively. It was also used to generate viable and healthy transgenic Arabidopsis thaliana plants that inducibly initiate HR. Beyond enabling studies on the ETI pathway, our regulatory strategy is generally applicable to reduce or eliminate undesired background expression of transgenes.
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Affiliation(s)
- Tania L Gonzalez
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Yan Liang
- Joint BioEnergy Institute, 5885 Hollis St, Emeryville, CA 94608, USA Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Bao N Nguyen
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Brian J Staskawicz
- Department of Plant & Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Dominique Loqué
- Joint BioEnergy Institute, 5885 Hollis St, Emeryville, CA 94608, USA Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ming C Hammond
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Department of Chemistry, University of California, Berkeley, CA 94720, USA
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Legionella pneumophila Effector LpdA Is a Palmitoylated Phospholipase D Virulence Factor. Infect Immun 2015. [PMID: 26216420 DOI: 10.1128/iai.00785-15] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Legionella pneumophila is a bacterial pathogen that thrives in alveolar macrophages, causing a severe pneumonia. The virulence of L. pneumophila depends on its Dot/Icm type IV secretion system (T4SS), which delivers more than 300 effector proteins into the host, where they rewire cellular signaling to establish a replication-permissive niche, the Legionella-containing vacuole (LCV). Biogenesis of the LCV requires substantial redirection of vesicle trafficking and remodeling of intracellular membranes. In order to achieve this, several T4SS effectors target regulators of membrane trafficking, while others resemble lipases. Here, we characterized LpdA, a phospholipase D effector, which was previously proposed to modulate the lipid composition of the LCV. We found that ectopically expressed LpdA was targeted to the plasma membrane and Rab4- and Rab14-containing vesicles. Subcellular targeting of LpdA required a C-terminal motif, which is posttranslationally modified by S-palmitoylation. Substrate specificity assays showed that LpdA hydrolyzed phosphatidylinositol, -inositol-3- and -4-phosphate, and phosphatidylglycerol to phosphatidic acid (PA) in vitro. In HeLa cells, LpdA generated PA at vesicles and the plasma membrane. Imaging of different phosphatidylinositol phosphate (PIP) and organelle markers revealed that while LpdA did not impact on membrane association of various PIP probes, it triggered fragmentation of the Golgi apparatus. Importantly, although LpdA is translocated inefficiently into cultured cells, an L. pneumophila ΔlpdA mutant displayed reduced replication in murine lungs, suggesting that it is a virulence factor contributing to L. pneumophila infection in vivo.
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Agarwal S, Agarwal S, Biancucci M, Satchell KJF. Induced autoprocessing of the cytopathic Makes caterpillars floppy-like effector domain of the Vibrio vulnificus MARTX toxin. Cell Microbiol 2015; 17:1494-509. [PMID: 25912102 DOI: 10.1111/cmi.12451] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/16/2015] [Accepted: 04/17/2015] [Indexed: 12/22/2022]
Abstract
The multifunctional-autoprocessing repeats-in-toxin (MARTX(Vv)) toxin that harbours a varied repertoire of effector domains is the primary virulence factor of Vibrio vulnificus. Although ubiquitously present among Biotype I toxin variants, the 'Makes caterpillars floppy-like' effector domain (MCF(Vv)) is previously unstudied. Using transient expression and protein delivery, MCF(Vv) and MCF(Ah) from the Aeromonas hydrophila MARTX(Ah)) toxin are shown for the first time to induce cell rounding. Alanine mutagenesis across the C-terminal subdomain of MCF(Vv) identified an Arg-Cys-Asp (RCD) tripeptide motif shown to comprise a cysteine protease catalytic site essential for autoprocessing of MCF(Vv). The autoprocessing could be recapitulated in vitro by the addition of host cell lysate to recombinant MCF(Vv), indicating induced autoprocessing by cellular factors. The RCD motif is also essential for cytopathicity, suggesting autoprocessing is essential first to activate the toxin and then to process a cellular target protein resulting in cell rounding. Sequence homology places MCF(Vv) within the C58 cysteine protease family that includes the type III secretion effectors YopT from Yersinia spp. and AvrPphB from Pseudomonas syringae. However, the catalytic site RCD motif is unique compared with other C58 peptidases and is here proposed to represent a new subgroup of autopeptidase found within a number of putative large bacterial toxins.
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Affiliation(s)
- Shivangi Agarwal
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Shivani Agarwal
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Marco Biancucci
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Karla J F Satchell
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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Boyle PC, Martin GB. Greasy tactics in the plant-pathogen molecular arms race. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1607-16. [PMID: 25725095 DOI: 10.1093/jxb/erv059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The modification of proteins by the attachment of fatty acids is a targeting tactic involved in mechanisms of both plant immunity and bacterial pathogenesis. The plant plasma membrane (PM) is a key battleground in the war against disease-causing microbes. This membrane is armed with an array of sensor proteins that function as a surveillance system to detect invading pathogens. Several of these sensor proteins are directed to the plasma membrane through the covalent addition of fatty acids, a process termed fatty acylation. Phytopathogens secrete effector proteins into the plant cell to subvert these surveillance mechanisms, rendering the host susceptible to infection. The targeting of effectors to specific locales within plant cells, particularly the internal face of the host PM, is critical for their virulence function. Several bacterial effectors hijack the host fatty acylation machinery to be modified and directed to this contested locale. To find and fight these fatty acylated effectors the plant leverages lipid-modified intracellular sensors. This review provides examples featuring how fatty acylation is a battle tactic used by both combatants in the molecular arms race between plants and pathogens. Also highlighted is the exploitation of a specific form of host-mediated fatty acid modification, which appears to be exclusively employed by phytopathogenic effector proteins.
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Affiliation(s)
- Patrick C Boyle
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA
| | - Gregory B Martin
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
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Lowe RGT, McCorkelle O, Bleackley M, Collins C, Faou P, Mathivanan S, Anderson M. Extracellular peptidases of the cereal pathogen Fusarium graminearum. FRONTIERS IN PLANT SCIENCE 2015; 6:962. [PMID: 26635820 PMCID: PMC4645717 DOI: 10.3389/fpls.2015.00962] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/22/2015] [Indexed: 05/22/2023]
Abstract
The plant pathogenic fungus Fusarium graminearum (Fgr) creates economic and health risks in cereals agriculture. Fgr causes head blight (or scab) of wheat and stalk rot of corn, reducing yield, degrading grain quality, and polluting downstream food products with mycotoxins. Fungal plant pathogens must secrete proteases to access nutrition and to breakdown the structural protein component of the plant cell wall. Research into the proteolytic activity of Fgr is hindered by the complex nature of the suite of proteases secreted. We used a systems biology approach comprising genome analysis, transcriptomics and label-free quantitative proteomics to characterize the peptidases deployed by Fgr during growth. A combined analysis of published microarray transcriptome datasets revealed seven transcriptional groupings of peptidases based on in vitro growth, in planta growth, and sporulation behaviors. A high resolution mass spectrometry-based proteomics analysis defined the extracellular proteases secreted by F. graminearum. A meta-classification based on sequence characters and transcriptional/translational activity in planta and in vitro provides a platform to develop control strategies that target Fgr peptidases.
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46
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Chen S, Lang P, Chronis D, Zhang S, De Jong WS, Mitchum MG, Wang X. In planta processing and glycosylation of a nematode CLAVATA3/ENDOSPERM SURROUNDING REGION-like effector and its interaction with a host CLAVATA2-like receptor to promote parasitism. PLANT PHYSIOLOGY 2015; 167:262-72. [PMID: 25416475 PMCID: PMC4281011 DOI: 10.1104/pp.114.251637] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Like other biotrophic plant pathogens, plant-parasitic nematodes secrete effector proteins into host cells to facilitate infection. Effector proteins that mimic plant CLAVATA3/ENDOSPERM SURROUNDING REGION-related (CLE) proteins have been identified in several cyst nematodes, including the potato cyst nematode (PCN); however, the mechanistic details of this cross-kingdom mimicry are poorly understood. Plant CLEs are posttranslationally modified and proteolytically processed to function as bioactive ligands critical to various aspects of plant development. Using ectopic expression coupled with nanoliquid chromatography-tandem mass spectrometry analysis, we show that the in planta mature form of proGrCLE1, a multidomain CLE effector secreted by PCN during infection, is a 12-amino acid arabinosylated glycopeptide (named GrCLE1-1Hyp4,7g) with striking structural similarity to mature plant CLE peptides. This glycopeptide is more resistant to hydrolytic degradation and binds with higher affinity to a CLAVATA2-like receptor (StCLV2) from potato (Solanum tuberosum) than its nonglycosylated forms. We further show that StCLV2 is highly up-regulated at nematode infection sites and that transgenic potatoes with reduced StCLV2 expression are less susceptible to PCN infection, indicating that interference of the CLV2-mediated signaling pathway confers nematode resistance in crop plants. These results strongly suggest that phytonematodes have evolved to utilize host cellular posttranslational modification and processing machinery for the activation of CLE effectors following secretion into plant cells and highlight the significance of arabinosylation in regulating nematode CLE effector activity. Our finding also provides evidence that multidomain CLEs are modified and processed similarly to single-domain CLEs, adding new insight into CLE maturation in plants.
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Affiliation(s)
- Shiyan Chen
- Department of Plant Pathology and Plant-Microbe Biology (S.C., P.L., X.W.), Proteomics and Mass Spectrometry Facility, Institute of Biotechnology and Life Science Technologies (S.Z.), and Department of Plant Breeding and Genetics (W.S.D.J.), Cornell University, Ithaca, New York 14853;Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853 (D.C., X.W.); andDivision of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (M.G.M.)
| | - Ping Lang
- Department of Plant Pathology and Plant-Microbe Biology (S.C., P.L., X.W.), Proteomics and Mass Spectrometry Facility, Institute of Biotechnology and Life Science Technologies (S.Z.), and Department of Plant Breeding and Genetics (W.S.D.J.), Cornell University, Ithaca, New York 14853;Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853 (D.C., X.W.); andDivision of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (M.G.M.)
| | - Demosthenis Chronis
- Department of Plant Pathology and Plant-Microbe Biology (S.C., P.L., X.W.), Proteomics and Mass Spectrometry Facility, Institute of Biotechnology and Life Science Technologies (S.Z.), and Department of Plant Breeding and Genetics (W.S.D.J.), Cornell University, Ithaca, New York 14853;Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853 (D.C., X.W.); andDivision of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (M.G.M.)
| | - Sheng Zhang
- Department of Plant Pathology and Plant-Microbe Biology (S.C., P.L., X.W.), Proteomics and Mass Spectrometry Facility, Institute of Biotechnology and Life Science Technologies (S.Z.), and Department of Plant Breeding and Genetics (W.S.D.J.), Cornell University, Ithaca, New York 14853;Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853 (D.C., X.W.); andDivision of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (M.G.M.)
| | - Walter S De Jong
- Department of Plant Pathology and Plant-Microbe Biology (S.C., P.L., X.W.), Proteomics and Mass Spectrometry Facility, Institute of Biotechnology and Life Science Technologies (S.Z.), and Department of Plant Breeding and Genetics (W.S.D.J.), Cornell University, Ithaca, New York 14853;Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853 (D.C., X.W.); andDivision of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (M.G.M.)
| | - Melissa G Mitchum
- Department of Plant Pathology and Plant-Microbe Biology (S.C., P.L., X.W.), Proteomics and Mass Spectrometry Facility, Institute of Biotechnology and Life Science Technologies (S.Z.), and Department of Plant Breeding and Genetics (W.S.D.J.), Cornell University, Ithaca, New York 14853;Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853 (D.C., X.W.); andDivision of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (M.G.M.)
| | - Xiaohong Wang
- Department of Plant Pathology and Plant-Microbe Biology (S.C., P.L., X.W.), Proteomics and Mass Spectrometry Facility, Institute of Biotechnology and Life Science Technologies (S.Z.), and Department of Plant Breeding and Genetics (W.S.D.J.), Cornell University, Ithaca, New York 14853;Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853 (D.C., X.W.); andDivision of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (M.G.M.)
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Deslandes L, Genin S. Opening the Ralstonia solanacearum type III effector tool box: insights into host cell subversion mechanisms. CURRENT OPINION IN PLANT BIOLOGY 2014; 20:110-7. [PMID: 24880553 DOI: 10.1016/j.pbi.2014.05.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/23/2014] [Accepted: 05/01/2014] [Indexed: 05/19/2023]
Abstract
Effectors delivered to host cells by the Type III secretion system are essential to Ralstonia solanacearum pathogenicity, as in several other plant pathogenic bacteria. The establishment of exhaustive effector repertoires in multiple R. solanacearum strains drew a first picture of the evolutionary dynamics of the pathogen effector suites. Effector repertoires are diversified, with a core of 20-30 effectors present in most of the strains and the obtention of mutants lacking one or more effector genes revealed the functional overlap among this effector network. Recent functional studies have provided insights into the ability of single effectors to manipulate the host proteasome, elicit cell death, trigger the expression of plant genes, and/or display biochemical activities on plant protein targets.
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Affiliation(s)
- Laurent Deslandes
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan F-31326, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan F-31326, France
| | - Stephane Genin
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan F-31326, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan F-31326, France.
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The bacterial effector HopX1 targets JAZ transcriptional repressors to activate jasmonate signaling and promote infection in Arabidopsis. PLoS Biol 2014; 12:e1001792. [PMID: 24558350 PMCID: PMC3928049 DOI: 10.1371/journal.pbio.1001792] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 01/09/2014] [Indexed: 11/19/2022] Open
Abstract
Pathogenicity of Pseudomonas syringae is dependent on a type III secretion system, which secretes a suite of virulence effector proteins into the host cytoplasm, and the production of a number of toxins such as coronatine (COR), which is a mimic of the plant hormone jasmonate-isoleuce (JA-Ile). Inside the plant cell, effectors target host molecules to subvert the host cell physiology and disrupt defenses. However, despite the fact that elucidating effector action is essential to understanding bacterial pathogenesis, the molecular function and host targets of the vast majority of effectors remain largely unknown. Here, we found that effector HopX1 from Pseudomonas syringae pv. tabaci (Pta) 11528, a strain that does not produce COR, interacts with and promotes the degradation of JAZ proteins, a key family of JA-repressors. We show that hopX1 encodes a cysteine protease, activity that is required for degradation of JAZs by HopX1. HopX1 associates with JAZ proteins through its central ZIM domain and degradation occurs in a COI1-independent manner. Moreover, ectopic expression of HopX1 in Arabidopsis induces the expression of JA-dependent genes, represses salicylic acid (SA)-induced markers, and complements the growth of a COR-deficient P. syringae pv. tomato (Pto) DC3000 strain during natural bacterial infections. Furthermore, HopX1 promoted susceptibility when delivered by the natural type III secretion system, to a similar extent as the addition of COR, and this effect was dependent on its catalytic activity. Altogether, our results indicate that JAZ proteins are direct targets of bacterial effectors to promote activation of JA-induced defenses and susceptibility in Arabidopsis. HopX1 illustrates a paradigm of an alternative evolutionary solution to COR with similar physiological outcome.
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Ruhanen H, Hurley D, Ghosh A, O'Brien KT, Johnston CR, Shields DC. Potential of known and short prokaryotic protein motifs as a basis for novel peptide-based antibacterial therapeutics: a computational survey. Front Microbiol 2014; 5:4. [PMID: 24478765 PMCID: PMC3896991 DOI: 10.3389/fmicb.2014.00004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 01/05/2014] [Indexed: 11/13/2022] Open
Abstract
Short linear motifs (SLiMs) are functional stretches of protein sequence that are of crucial importance for numerous biological processes by mediating protein-protein interactions. These motifs often comprise peptides of less than 10 amino acids that modulate protein-protein interactions. While well-characterized in eukaryotic intracellular signaling, their role in prokaryotic signaling is less well-understood. We surveyed the distribution of known motifs in prokaryotic extracellular and virulence proteins across a range of bacterial species and conducted searches for novel motifs in virulence proteins. Many known motifs in virulence effector proteins mimic eukaryotic motifs and enable the pathogen to control the intracellular processes of their hosts. Novel motifs were detected by finding those that had evolved independently in three or more unrelated virulence proteins. The search returned several significantly over-represented linear motifs of which some were known motifs and others are novel candidates with potential roles in bacterial pathogenesis. A putative C-terminal G[AG].$ motif found in type IV secretion system proteins was among the most significant detected. A KK$ motif that has been previously identified in a plasminogen-binding protein, was demonstrated to be enriched across a number of adhesion and lipoproteins. While there is some potential to develop peptide drugs against bacterial infection based on bacterial peptides that mimic host components, this could have unwanted effects on host signaling. Thus, novel SLiMs in virulence factors that do not mimic host components but are crucial for bacterial pathogenesis, such as the type IV secretion system, may be more useful to develop as leads for anti-microbial peptides or drugs.
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Affiliation(s)
- Heini Ruhanen
- Complex and Adaptive Systems Laboratory, University College Dublin Dublin, Ireland ; Conway Institute of Biomolecular and Biomedical Science, University College Dublin Dublin, Ireland ; School of Medicine and Medical Science, University College Dublin Dublin, Ireland
| | - Daniel Hurley
- Complex and Adaptive Systems Laboratory, University College Dublin Dublin, Ireland ; Conway Institute of Biomolecular and Biomedical Science, University College Dublin Dublin, Ireland ; School of Medicine and Medical Science, University College Dublin Dublin, Ireland
| | - Ambarnil Ghosh
- Crystallography and Molecular Biology Department, Saha Institute of Nuclear Physics Kolkata, India
| | - Kevin T O'Brien
- Complex and Adaptive Systems Laboratory, University College Dublin Dublin, Ireland ; Conway Institute of Biomolecular and Biomedical Science, University College Dublin Dublin, Ireland ; School of Medicine and Medical Science, University College Dublin Dublin, Ireland
| | | | - Denis C Shields
- Complex and Adaptive Systems Laboratory, University College Dublin Dublin, Ireland ; Conway Institute of Biomolecular and Biomedical Science, University College Dublin Dublin, Ireland ; School of Medicine and Medical Science, University College Dublin Dublin, Ireland
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Qi D, Dubiella U, Kim SH, Sloss DI, Dowen RH, Dixon JE, Innes RW. Recognition of the protein kinase AVRPPHB SUSCEPTIBLE1 by the disease resistance protein RESISTANCE TO PSEUDOMONAS SYRINGAE5 is dependent on s-acylation and an exposed loop in AVRPPHB SUSCEPTIBLE1. PLANT PHYSIOLOGY 2014; 164:340-51. [PMID: 24225654 PMCID: PMC3875812 DOI: 10.1104/pp.113.227686] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 11/12/2013] [Indexed: 05/06/2023]
Abstract
The recognition of pathogen effector proteins by plants is typically mediated by intracellular receptors belonging to the nucleotide-binding leucine-rich repeat (NLR) family. NLR proteins often detect pathogen effector proteins indirectly by detecting modification of their targets. How NLR proteins detect such modifications is poorly understood. To address these questions, we have been investigating the Arabidopsis (Arabidopsis thaliana) NLR protein RESISTANCE TO PSEUDOMONAS SYRINGAE5 (RPS5), which detects the Pseudomonas syringae effector protein Avirulence protein Pseudomonas phaseolicolaB (AvrPphB). AvrPphB is a cysteine protease that specifically targets a subfamily of receptor-like cytoplasmic kinases, including the Arabidopsis protein kinase AVRPPHB Susceptible1 (PBS1). RPS5 is activated by the cleavage of PBS1 at the apex of its activation loop. Here, we show that RPS5 activation requires that PBS1 be localized to the plasma membrane and that plasma membrane localization of PBS1 is mediated by amino-terminal S-acylation. We also describe the development of a high-throughput screen for mutations in PBS1 that block RPS5 activation, which uncovered four new pbs1 alleles, two of which blocked cleavage by AvrPphB. Lastly, we show that RPS5 distinguishes among closely related kinases by the amino acid sequence (SEMPH) within an exposed loop in the C-terminal one-third of PBS1. The SEMPH loop is located on the opposite side of PBS1 from the AvrPphB cleavage site, suggesting that RPS5 associates with the SEMPH loop while leaving the AvrPphB cleavage site exposed. These findings provide support for a model of NLR activation in which NLR proteins form a preactivation complex with effector targets and then sense a conformational change in the target induced by effector modification.
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Affiliation(s)
| | | | | | - D. Isaiah Sloss
- Department of Biology, Indiana University, Bloomington, Indiana 47405 (D.Q., U.D., S.H.K., D.I.S., R.W.I.)
- Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry and Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, California 92093 (R.H.D, J.E.D.); and
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815 (J.E.D.)
| | - Robert H. Dowen
- Department of Biology, Indiana University, Bloomington, Indiana 47405 (D.Q., U.D., S.H.K., D.I.S., R.W.I.)
- Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry and Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, California 92093 (R.H.D, J.E.D.); and
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815 (J.E.D.)
| | - Jack E. Dixon
- Department of Biology, Indiana University, Bloomington, Indiana 47405 (D.Q., U.D., S.H.K., D.I.S., R.W.I.)
- Departments of Pharmacology, Cellular and Molecular Medicine, and Chemistry and Biochemistry and Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, California 92093 (R.H.D, J.E.D.); and
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815 (J.E.D.)
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