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Ong ZWEBB. Unravelling bacterial virulence factors in yeast: From identification to the elucidation of their mechanisms of action. Arch Microbiol 2024; 206:303. [PMID: 38878203 DOI: 10.1007/s00203-024-04023-2] [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: 04/19/2024] [Revised: 05/21/2024] [Accepted: 05/29/2024] [Indexed: 06/23/2024]
Abstract
Pathogenic bacteria employ virulence factors (VF) to establish infection and cause disease in their host. Yeasts, Saccharomyces cerevisiae and Saccharomyces pombe, are useful model organisms to study the functions of bacterial VFs and their interaction with targeted cellular processes because yeast processes and organelle structures are highly conserved and similar to higher eukaryotes. In this review, we describe the principles and applications of the yeast model for the identification and functional characterisation of bacterial VFs to investigate bacterial pathogenesis. The growth inhibition phenotype caused by the heterologous expression of bacterial VFs in yeast is commonly used to identify candidate VFs. Then, subcellular localisation patterns of bacterial VFs can provide further clues about their target molecules and functions during infection. Yeast knockout and overexpression libraries are also used to investigate VF interactions with conserved eukaryotic cell structures (e.g., cytoskeleton and plasma membrane), and cellular processes (e.g., vesicle trafficking, signalling pathways, and programmed cell death). In addition, the yeast growth inhibition phenotype is also useful for screening new drug leads that target and inhibit bacterial VFs. This review provides an updated overview of new tools, principles and applications to study bacterial VFs in yeast.
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2
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Lai WY, Wong Z, Chang CH, Samian MR, Watanabe N, Teh AH, Noordin R, Ong EBB. Identifying Leptospira interrogans putative virulence factors with a yeast protein expression screen. Appl Microbiol Biotechnol 2022; 106:6567-6581. [DOI: 10.1007/s00253-022-12160-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/17/2022] [Accepted: 08/30/2022] [Indexed: 11/24/2022]
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3
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Chen C, Dai Y, Yang Y, Zhu Z, Zhang Q, An X, Lai F. Lawsonia intracellularis LI0666 is a new EPIYA effector exported by the Yersinia enterocolitica type III secretion system. Vet Res 2022; 53:39. [PMID: 35659762 PMCID: PMC9167531 DOI: 10.1186/s13567-022-01054-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/04/2022] [Indexed: 11/16/2022] Open
Abstract
Lawsonia intracellularis is the causative agent of proliferative enteropathy. While it harbors genes encoding the entire apparatus required for the type III secretion system (T3SS) and the expression of some of these components has been detected during experimental infection, the identification of L. intracellularis T3SS substrates (effector proteins) has been hampered. The Yersinia T3SS and yeast growth inhibition assays are two important heterologous systems used for the characterization of effector proteins. Bacterial EPIYA effectors are a distinct class of bacterial effectors defined by the presence of EPIYA or the EPIYA-related motif. When delivered into host cells via a T3SS or type IV secretion system, these effectors undergo tyrosine phosphorylation of the EPIYA motif, which enables them to manipulate host cell signaling by promiscuously interacting with multiple SH2 domain-containing proteins. A previous study showed that L. intracellularis LI0666 contains two EPIYA motifs and speculated that this protein could be a T3SS effector. In this study, we show that LI0666 is secreted by Yersinia in a T3SS-dependent manner and inhibits yeast growth. LI0666 is phosphorylated at tyrosine residues in porcine intestinal epithelial cells and in human epithelial cells. Like the archetypal EPIYA effector CagA, the EPIYA-containing region is not required for LI0666 association with yeast and mammalian cell membranes. Our results indicate that LI0666 is an authentic bacterial EPIYA effector. Identification of the tyrosine kinases that are responsible for LI0666 phosphorylation and the SH2 domain-containing host proteins that LI0666 interacts with will help to explore the molecular mechanisms of LI0666 in disease development.
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Affiliation(s)
- Cang Chen
- College of Bioscience and Bioengineering, Jiangxi Key Laboratory for Conservation and Utilization of Fungal Resources, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Yimin Dai
- College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Yingying Yang
- College of Bioscience and Bioengineering, Jiangxi Key Laboratory for Conservation and Utilization of Fungal Resources, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Zihe Zhu
- College of Bioscience and Bioengineering, Jiangxi Key Laboratory for Conservation and Utilization of Fungal Resources, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Qinghua Zhang
- College of Bioscience and Bioengineering, Jiangxi Key Laboratory for Conservation and Utilization of Fungal Resources, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Xuejiao An
- College of Bioscience and Bioengineering, Jiangxi Key Laboratory for Conservation and Utilization of Fungal Resources, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Fenju Lai
- College of Bioscience and Bioengineering, Jiangxi Key Laboratory for Conservation and Utilization of Fungal Resources, Jiangxi Agricultural University, Nanchang, 330045, China. .,Collaborative Innovation Center of Postharvest Key Technology and Quality Safety of Fruits and Vegetables in Jiangxi Province, Nanchang, Jiangxi, China.
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Wilson AC, Morgan WR. Functional analysis of a Phytophthora host-translocated effector using the yeast model system. PeerJ 2021; 9:e12576. [PMID: 34966585 PMCID: PMC8663620 DOI: 10.7717/peerj.12576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 11/09/2021] [Indexed: 11/20/2022] Open
Abstract
Background Phytophthora plant pathogens secrete effector proteins that are translocated into host plant cells during infection and collectively contribute to pathogenicity. A subset of these host-translocated effectors can be identified by the amino acid motif RXLR (arginine, any amino acid, leucine, arginine). Bioinformatics analysis has identified hundreds of putative RXLR effector genes in Phytophthora genomes, but the specific molecular function of most remains unknown. Methods Here we describe initial studies to investigate the use of Saccharomyces cerevisiae as a eukaryotic model to explore the function of Phytophthora RXLR effector proteins. Results and Conclusions Expression of individual RXLR effectors in yeast inhibited growth, consistent with perturbation of a highly conserved cellular process. Transcriptome analysis of yeast cells expressing the poorly characterized P. sojae RXLR effector Avh110 identified nearly a dozen yeast genes whose expression levels were altered greater than two-fold compared to control cells. All five of the most down-regulated yeast genes are normally induced under low phosphate conditions via the PHO4 transcription factor, indicating that PsAvh110 perturbs the yeast regulatory network essential for phosphate homeostasis and suggesting likely PsAvh110 targets during P. sojae infection of its soybean host.
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Affiliation(s)
- Avery C Wilson
- Department of Biology, The College of Wooster, Wooster, OH, United States.,School of Medicine, New York Medical College, Valhalla, NY, United States
| | - William R Morgan
- Department of Biology, The College of Wooster, Wooster, OH, United States
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5
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Li D, Zhang ZT, He CW, Xie Z. Yeast Lipid Extraction and Analysis by HPTLC. Bio Protoc 2021; 11:e4081. [PMID: 34327278 DOI: 10.21769/bioprotoc.4081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/17/2021] [Accepted: 04/14/2021] [Indexed: 11/02/2022] Open
Abstract
The diversity of lipid structures, properties, and combinations in biological tissues makes their extraction and analysis an experimental challenge. Accordingly, even for one of the simplest single-cellular fungi, the budding yeast (Saccharomyces cerevisiae), numerous extraction and analysis protocols have been developed to separate and quantitate the different molecular lipid species. Among them, most are quite sophisticated and tricky to follow. Herein, we describe a yeast total lipids extraction procedure with a relatively good yield, which is appropriate for subsequent thin-layer chromatography (TLC) or liquid chromatography-mass (LC-MS) analysis. We then discuss the most widely used solvent systems to separate yeast phospholipids and neutral lipids by TLC. Finally, we describe an easy and rapid method for silica gel staining by a Coomassie Brilliant Blue-methanol mixture. The stained lipid species can then be quantitated using imaging software such as ImageJ. Overall, the methods described in this protocol are time-saving and novice-friendly.
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Affiliation(s)
- Dan Li
- Department of Nutrition & Clinical Assessment Center of Functional Foods & Translational Medicine Research Center, Affiliated Hospital of Jiangnan University, Wuxi, China.,State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zheng-Tan Zhang
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Cheng-Wen He
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zhiping Xie
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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dos Santos KCG, Pelletier G, Séguin A, Guillemette F, Hawkes J, Desgagné-Penix I, Germain H. Unrelated Fungal Rust Candidate Effectors Act on Overlapping Plant Functions. Microorganisms 2021; 9:microorganisms9050996. [PMID: 34063040 PMCID: PMC8148019 DOI: 10.3390/microorganisms9050996] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/23/2021] [Accepted: 04/30/2021] [Indexed: 11/21/2022] Open
Abstract
Rust fungi cause epidemics that threaten the production of important plant species, such as wheat and soy. Melampsora larici-populina (Mlp) causes the poplar rust and encodes at least 1184 candidate effectors (CEs) whose functions are poorly known. In this study, we sequenced the transcriptome and used mass spectrometry to analyze the metabolome of Arabidopsis plants constitutively expressing 14 Mlp CEs and of a control line to discover alterations leading to plant susceptibility. We found 2299 deregulated genes across the experiment. Genes involved in pattern-triggered immunity, such as FRK1, PR1, RBOHD, and WRKY33, as well as AUX/IAA genes were down-regulated. We further observed that 680 metabolites were deregulated in at least one CE-expressing transgenic line, with “highly unsaturated and phenolic compounds” and “peptides” enriched among down- and up-regulated metabolites. Interestingly, transgenic lines expressing unrelated CEs had correlated patterns of gene and metabolite deregulation, while expression of CEs belonging to the same family deregulated different genes and metabolites. Thus, our results uncouple effector sequence similarity and function. This supports that effector functional investigation in the context of their virulence activity and effect on plant susceptibility requires the investigation of the individual effector and precludes generalization based on sequence similarity.
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Affiliation(s)
- Karen Cristine Goncalves dos Santos
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H9, Canada; (K.C.G.d.S.); (I.D.-P.)
- Plant Biology Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 1V3, Canada
| | - Gervais Pelletier
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Quebec City, QC G1V 4C7, Canada; (G.P.); (A.S.)
| | - Armand Séguin
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Quebec City, QC G1V 4C7, Canada; (G.P.); (A.S.)
| | - François Guillemette
- Centre for Research on Aquatic Ecosystem Interactions (RIVE), Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 1V3, Canada;
| | - Jeffrey Hawkes
- Department of Chemistry—BMC, Analytical Chemistry, Uppsala University, VJ2J+92 Uppsala, Sweden;
| | - Isabel Desgagné-Penix
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H9, Canada; (K.C.G.d.S.); (I.D.-P.)
- Plant Biology Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 1V3, Canada
| | - Hugo Germain
- Department of Chemistry, Biochemistry and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H9, Canada; (K.C.G.d.S.); (I.D.-P.)
- Plant Biology Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC G8Z 1V3, Canada
- Correspondence:
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Friedrich A, Beare PA, Schulze-Luehrmann J, Cordsmeier A, Pazen T, Sonnewald S, Lührmann A. The Coxiella burnetii effector protein CaeB modulates endoplasmatic reticulum (ER) stress signalling and is required for efficient replication in Galleria mellonella. Cell Microbiol 2021; 23:e13305. [PMID: 33355405 DOI: 10.1111/cmi.13305] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 12/15/2020] [Accepted: 12/20/2020] [Indexed: 01/02/2023]
Abstract
The obligate intracellular pathogen Coxiella burnetii is the causative agent of the zoonosis Q fever. C. burnetii infection can have severe outcomes due to the development of chronic infection. To establish and maintain an infection, C. burnetii depends on a functional type IVB secretion system (T4BSS) and, thus, on the translocation of effector proteins into the host cell. Here, we showed that the C. burnetii T4BSS effector protein CaeB targets the conserved endoplasmatic reticulum (ER) stress sensor IRE1 during ER stress in mammalian and plant cells. CaeB-induced upregulation of IRE1 RNase activity was essential for CaeB-mediated inhibition of ER stress-induced cell death. Our data reveal a novel role for CaeB in ER stress signalling modulation and demonstrate that CaeB is involved in pathogenicity in vivo. Furthermore, we provide evidence that C. burnetii infection leads to modulation of the ER stress sensors IRE1 and PERK, but not ATF6 during ER stress. While the upregulation of the RNase activity of IRE1 during ER stress depends on CaeB, modulation of PERK is CaeB independent, suggesting that C. burnetii encodes several factors influencing ER stress during infection.
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Affiliation(s)
- Anja Friedrich
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.,Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Arne Cordsmeier
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tobias Pazen
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sophia Sonnewald
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
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8
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Ratu STN, Hirata A, Kalaw CO, Yasuda M, Tabuchi M, Okazaki S. Multiple Domains in the Rhizobial Type III Effector Bel2-5 Determine Symbiotic Efficiency With Soybean. FRONTIERS IN PLANT SCIENCE 2021; 12:689064. [PMID: 34163515 PMCID: PMC8215712 DOI: 10.3389/fpls.2021.689064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/10/2021] [Indexed: 05/06/2023]
Abstract
Bradyrhizobium elkanii utilizes the type III effector Bel2-5 for nodulation in host plants in the absence of Nod factors (NFs). In soybean plants carrying the Rj4 allele, however, Bel2-5 causes restriction of nodulation by triggering immune responses. Bel2-5 shows similarity with XopD of the phytopathogen Xanthomonas campestris pv. vesicatoria and possesses two internal repeat sequences, two ethylene (ET)-responsive element-binding factor-associated amphiphilic repression (EAR) motifs, a nuclear localization signal (NLS), and a ubiquitin-like protease (ULP) domain, which are all conserved in XopD except for the repeat domains. By mutational analysis, we revealed that most of the putative domains/motifs in Bel2-5 were essential for both NF-independent nodulation and nodulation restriction in Rj4 soybean. The expression of soybean symbiosis- and defense-related genes was also significantly altered by inoculation with the bel2-5 domain/motif mutants compared with the expression upon inoculation with wild-type B. elkanii, which was mostly consistent with the phenotypic changes of nodulation in host plants. Notably, the functionality of Bel2-5 was mostly correlated with the growth inhibition effect of Bel2-5 expressed in yeast cells. The nodulation phenotypes of the domain-swapped mutants of Bel2-5 and XopD indicated that both the C-terminal ULP domain and upstream region are required for the Bel2-5-dependent nodulation phenotypes. These results suggest that Bel2-5 interacts with and modifies host targets via these multiple domains to execute both NF-independent symbiosis and nodulation restriction in Rj4 soybean.
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Affiliation(s)
- Safirah Tasa Nerves Ratu
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Atsushi Hirata
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Kagawa, Japan
| | - Christian Oliver Kalaw
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Michiko Yasuda
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Mitsuaki Tabuchi
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Kagawa, Japan
| | - Shin Okazaki
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Japan
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
- *Correspondence: Shin Okazaki,
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9
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Kovalev N, Pogany J, Nagy PD. Reconstitution of an RNA Virus Replicase in Artificial Giant Unilamellar Vesicles Supports Full Replication and Provides Protection for the Double-Stranded RNA Replication Intermediate. J Virol 2020; 94:e00267-20. [PMID: 32641477 PMCID: PMC7459549 DOI: 10.1128/jvi.00267-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/29/2020] [Indexed: 01/23/2023] Open
Abstract
Positive-strand RNA [(+)RNA] viruses are important pathogens of humans, animals, and plants and replicate inside host cells by coopting numerous host factors and subcellular membranes. To gain insights into the assembly of viral replicase complexes (VRCs) and dissect the roles of various lipids and coopted host factors, we have reconstituted Tomato bushy stunt virus (TBSV) replicase using artificial giant unilamellar vesicles (GUVs). We demonstrate that reconstitution of VRCs on GUVs with endoplasmic reticulum (ER)-like phospholipid composition results in a complete cycle of replication and asymmetrical RNA synthesis, which is a hallmark of (+)RNA viruses. TBSV VRCs assembled on GUVs provide significant protection of the double-stranded RNA (dsRNA) replication intermediate against the dsRNA-specific RNase III. The lipid compositions of GUVs have pronounced effects on in vitro TBSV replication, including (-) and (+)RNA synthesis. The GUV-based assay has led to the discovery of the critical role of phosphatidylserine in TBSV replication and a novel role for phosphatidylethanolamine in asymmetrical (+)RNA synthesis. The GUV-based assay also showed stimulatory effects by phosphatidylinositol-3-phosphate [PI(3)P] and ergosterol on TBSV replication. We demonstrate that eEF1A and Hsp70 coopted replicase assembly factors, Vps34 phosphatidylinositol 3-kinase (PI3K) and the membrane-bending ESCRT factors, are required for reconstitution of the active TBSV VRCs in GUVs, further supporting that the novel GUV-based in vitro approach recapitulates critical steps and involves essential coopted cellular factors of the TBSV replication process. Taken together, this novel GUV assay will be highly suitable to dissect the functions of viral and cellular factors in TBSV replication.IMPORTANCE Understanding the mechanism of replication of positive-strand RNA viruses, which are major pathogens of plants, animals, and humans, can lead to new targets for antiviral interventions. These viruses subvert intracellular membranes for virus replication and coopt numerous host proteins, whose functions during virus replication are not yet completely defined. To dissect the roles of various host factors in Tomato bushy stunt virus (TBSV) replication, we have developed an artificial giant unilamellar vesicle (GUV)-based replication assay. The GUV-based in vitro approach recapitulates critical steps of the TBSV replication process. GUV-based reconstitution of the TBSV replicase revealed the need for a complex mixture of phospholipids, especially phosphatidylserine and phosphatidylethanolamine, in TBSV replication. The GUV-based approach will be useful to dissect the functions of essential coopted cellular factors.
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Affiliation(s)
- Nikolay Kovalev
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Judit Pogany
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
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10
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Slater SL, Frankel G. Advances and Challenges in Studying Type III Secretion Effectors of Attaching and Effacing Pathogens. Front Cell Infect Microbiol 2020; 10:337. [PMID: 32733819 PMCID: PMC7358347 DOI: 10.3389/fcimb.2020.00337] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/04/2020] [Indexed: 12/24/2022] Open
Affiliation(s)
- Sabrina L Slater
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Gad Frankel
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, United Kingdom
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11
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Inaba JI, Xu K, Kovalev N, Ramanathan H, Roy CR, Lindenbach BD, Nagy PD. Screening Legionella effectors for antiviral effects reveals Rab1 GTPase as a proviral factor coopted for tombusvirus replication. Proc Natl Acad Sci U S A 2019; 116:21739-21747. [PMID: 31591191 PMCID: PMC6815150 DOI: 10.1073/pnas.1911108116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial virulence factors or effectors are proteins targeted into host cells to coopt or interfere with cellular proteins and pathways. Viruses often coopt the same cellular proteins and pathways to support their replication in infected cells. Therefore, we screened the Legionella pneumophila effectors to probe virus-host interactions and identify factors that modulate tomato bushy stunt virus (TBSV) replication in yeast surrogate host. Among 302 Legionella effectors tested, 28 effectors affected TBSV replication. To unravel a coopted cellular pathway in TBSV replication, the identified DrrA effector from Legionella was further exploited. We find that expression of DrrA in yeast or plants blocks TBSV replication through inhibiting the recruitment of Rab1 small GTPase and endoplasmic reticulum-derived COPII vesicles into the viral replication compartment. TBSV hijacks Rab1 and COPII vesicles to create enlarged membrane surfaces and optimal lipid composition within the viral replication compartment. To further validate our Legionella effector screen, we used the Legionella effector LepB lipid kinase to confirm the critical proviral function of PI(3)P phosphoinositide and the early endosomal compartment in TBSV replication. We demonstrate the direct inhibitory activity of LegC8 effector on TBSV replication using a cell-free replicase reconstitution assay. LegC8 inhibits the function of eEF1A, a coopted proviral host factor. Altogether, the identified bacterial effectors with anti-TBSV activity could be powerful reagents in cell biology and virus-host interaction studies. This study provides important proof of concept that bacterial effector proteins can be a useful toolbox to identify host factors and cellular pathways coopted by (+)RNA viruses.
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Affiliation(s)
- Jun-Ichi Inaba
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546
| | - Kai Xu
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546
| | - Nikolay Kovalev
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546
| | - Harish Ramanathan
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536
| | - Craig R Roy
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536
| | - Brett D Lindenbach
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536
| | - Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546;
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12
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Chua SCJH, Tan HQ, Engelberg D, Lim LHK. Alternative Experimental Models for Studying Influenza Proteins, Host-Virus Interactions and Anti-Influenza Drugs. Pharmaceuticals (Basel) 2019; 12:E147. [PMID: 31575020 PMCID: PMC6958409 DOI: 10.3390/ph12040147] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 09/11/2019] [Accepted: 09/12/2019] [Indexed: 12/14/2022] Open
Abstract
Ninety years after the discovery of the virus causing the influenza disease, this malady remains one of the biggest public health threats to mankind. Currently available drugs and vaccines only partially reduce deaths and hospitalizations. Some of the reasons for this disturbing situation stem from the sophistication of the viral machinery, but another reason is the lack of a complete understanding of the molecular and physiological basis of viral infections and host-pathogen interactions. Even the functions of the influenza proteins, their mechanisms of action and interaction with host proteins have not been fully revealed. These questions have traditionally been studied in mammalian animal models, mainly ferrets and mice (as well as pigs and non-human primates) and in cell lines. Although obviously relevant as models to humans, these experimental systems are very complex and are not conveniently accessible to various genetic, molecular and biochemical approaches. The fact that influenza remains an unsolved problem, in combination with the limitations of the conventional experimental models, motivated increasing attempts to use the power of other models, such as low eukaryotes, including invertebrate, and primary cell cultures. In this review, we summarized the efforts to study influenza in yeast, Drosophila, zebrafish and primary human tissue cultures and the major contributions these studies have made toward a better understanding of the disease. We feel that these models are still under-utilized and we highlight the unique potential each model has for better comprehending virus-host interactions and viral protein function.
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Affiliation(s)
- Sonja C J H Chua
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore.
- NUS Immunology Program, Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore.
- CREATE-NUS-HUJ Molecular Mechanisms of Inflammatory Diseases Programme, National University of Singapore, Singapore 138602, Singapore.
| | - Hui Qing Tan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore.
- NUS Immunology Program, Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore.
| | - David Engelberg
- CREATE-NUS-HUJ Molecular Mechanisms of Inflammatory Diseases Programme, National University of Singapore, Singapore 138602, Singapore.
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore.
- Department of Biological Chemistry, The Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | - Lina H K Lim
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore.
- NUS Immunology Program, Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore.
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13
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Yang L, Lai F, He L, Lu Y, Zhong Q, Lai C, Dai Y. LI1035, a putative effector secreted by Lawsonia intracellularis, targets the MAPK pathway and regulates actin organizationin yeast and mammalian cells. Vet Microbiol 2019; 235:127-135. [PMID: 31282370 DOI: 10.1016/j.vetmic.2019.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/17/2019] [Accepted: 06/10/2019] [Indexed: 11/17/2022]
Abstract
Lawsonia intracellularis is an obligate intracellular Gram-negative bacterium that has been identified as the etiological agent of the contagious disease proliferative enteropathy (PE) in a wide range of animals, mainly pigs. The genome sequence of L. intracellularis indicates that this bacterium possess a type III secretion system (T3SS), which may assist the bacterium during cell invasion and host innate immune system evasion and could be a mechanism for inducing cellular proliferation. However, the effectors secreted by the T3SS (T3Es) of L. intracellularis have not been reported. T3Es often target conserved eukaryotic cellular processes, and yeast is an established and robust model system in which to reveal their function. By screening the growth inhibition of an ordered array of Saccharomyces cerevisiae strains expressing the hypothetical genes of L. intracellularis, LI1035 was identified as the first putative effector that inhibits yeast growth. The LI1035-induced growth inhibition was rescued in two of the 14 mitogen-activated protein kinase (MAPK) yeast haploid deletion strains, suggesting that LI1035 interacts with the components of the MAPK pathway in yeast. Phosphorylation assays confirmed that LI1035 inhibits MAPK signaling cascades in yeast and mammalian cells. Actin staining assays revealed that LI1035 regulates actin organization in yeast and mammalian cells. Taken together, these results indicate that LI1035 alters MAPK pathway activity and regulates actin organization in the host. These findings may contribute to the understanding the pathogenesis of L. intracellularis and support the use of yeast as a heterologous system for the functional analysis of pathogen-specific gene products in the laboratory.
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Affiliation(s)
- Lijuan Yang
- School of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Fenju Lai
- School of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Lei He
- School of Life Science, Sun Yat-sen University, Guangzhou, 510275, China
| | - Yongjun Lu
- School of Life Science, Sun Yat-sen University, Guangzhou, 510275, China
| | - Qiwang Zhong
- School of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Chongde Lai
- School of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Yimin Dai
- School of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, China.
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14
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Zhang X, Hooykaas PJJ. The Agrobacterium VirD5 protein hyperactivates the mitotic Aurora kinase in host cells. THE NEW PHYTOLOGIST 2019; 222:1551-1560. [PMID: 30667529 PMCID: PMC6667905 DOI: 10.1111/nph.15700] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 01/13/2019] [Indexed: 06/08/2023]
Abstract
Aided by translocated virulence proteins, Agrobacterium tumefaciens transforms plant cells with oncogenic T-DNA. In the host cells the virulence protein VirD5 moves to the nucleus, where it becomes localized at the kinetochores, and disturbs faithful chromosome segregation, but the molecular mechanism underlying this remains unknown. To gain more insight, we screened amongst the kinetochore proteins for VirD5 interactors using bimolecular fluorescence complementation assays, and tested chromosome segregation in yeast cells. We found that VirD5 interacts with the conserved mitotic Aurora kinase Ipl1 in yeast and likewise with plant Aurora kinases. In vitro VirD5 was found to stimulate the activity of Ipl1. Phosphorylation of substrates by Ipl1 in vivo is known to result in the detachment between kinetochore and spindle microtubule. This is necessary for error correction, but increased Ipl1/Aurora kinase activity is known to cause spindle instability, explaining enhanced chromosome mis-segregation seen in the presence of VirD5. That activation of the Ipl1/Aurora kinase at least partially underlies the toxicity of VirD5 became apparent by artificial boosting the activity of the specific counteracting phosphatase Glc7 in vivo, which relieved the toxicity. These findings reveal a novel mechanism by which a pathogenic bacterium manipulates host cells.
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Affiliation(s)
- Xiaorong Zhang
- Department of Molecular and Developmental GeneticsInstitute of BiologyLeiden UniversitySylviusweg 72Leiden2333BEthe Netherlands
| | - Paul J. J. Hooykaas
- Department of Molecular and Developmental GeneticsInstitute of BiologyLeiden UniversitySylviusweg 72Leiden2333BEthe Netherlands
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15
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Patrick KL, Wojcechowskyj JA, Bell SL, Riba MN, Jing T, Talmage S, Xu P, Cabello AL, Xu J, Shales M, Jimenez-Morales D, Ficht TA, de Figueiredo P, Samuel JE, Li P, Krogan NJ, Watson RO. Quantitative Yeast Genetic Interaction Profiling of Bacterial Effector Proteins Uncovers a Role for the Human Retromer in Salmonella Infection. Cell Syst 2018; 7:323-338.e6. [PMID: 30077634 PMCID: PMC6160342 DOI: 10.1016/j.cels.2018.06.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/21/2018] [Accepted: 06/21/2018] [Indexed: 11/26/2022]
Abstract
Intracellular bacterial pathogens secrete a repertoire of effector proteins into host cells that are required to hijack cellular pathways and cause disease. Despite decades of research, the molecular functions of most bacterial effectors remain unclear. To address this gap, we generated quantitative genetic interaction profiles between 36 validated and putative effectors from three evolutionarily divergent human bacterial pathogens and 4,190 yeast deletion strains. Correlating effector-generated profiles with those of yeast mutants, we recapitulated known biology for several effectors with remarkable specificity and predicted previously unknown functions for others. Biochemical and functional validation in human cells revealed a role for an uncharacterized component of the Salmonella SPI-2 translocon, SseC, in regulating maintenance of the Salmonella vacuole through interactions with components of the host retromer complex. These results exhibit the power of genetic interaction profiling to discover and dissect complex biology at the host-pathogen interface.
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Affiliation(s)
- Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Jason A Wojcechowskyj
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Morgan N Riba
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Tao Jing
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Sara Talmage
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Pengbiao Xu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Ana L Cabello
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA; Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA; Norman Borlaug Center, Texas A&M University, College Station, TX 77843, USA
| | - Jiewei Xu
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA
| | - Michael Shales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA
| | - David Jimenez-Morales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA
| | - Thomas A Ficht
- Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA
| | - Paul de Figueiredo
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA; Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA; Norman Borlaug Center, Texas A&M University, College Station, TX 77843, USA
| | - James E Samuel
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA.
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA.
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16
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Carella P, Evangelisti E, Schornack S. Sticking to it: phytopathogen effector molecules may converge on evolutionarily conserved host targets in green plants. CURRENT OPINION IN PLANT BIOLOGY 2018; 44:175-180. [PMID: 30071474 PMCID: PMC6119762 DOI: 10.1016/j.pbi.2018.04.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/06/2018] [Accepted: 04/28/2018] [Indexed: 05/26/2023]
Abstract
•Phytopathogen effectors converge on similar sets of host proteins in angiosperms. •Effectors may target host proteins and processes present across the green plant lineage. •Bryophyte model plants are promising systems to investigate effector–target relationships. Plant-associated microbes secrete effector proteins that subvert host cellular machinery to facilitate the colonization of plant tissues and cells. Accumulating data suggests that independently evolved effectors from bacterial, fungal, and oomycete pathogens may converge on a similar set of host proteins in certain angiosperm models, however, whether this concept is relevant throughout the green plant lineage is unknown. Here, we explore the idea that pathogen effector molecules target host proteins present across evolutionarily distant land plant lineages to promote disease. We discuss that host proteins targeted by phytopathogens or integrated into angiosperm immune receptors are likely found across green plant genomes, from early diverging non-vascular lineages (bryophytes) to flowering plants (angiosperms). This would suggest that independently evolved pathogens might manipulate their hosts by targeting `vulnerability’ hubs that are present across land plants. Future work focusing on accessible early divergent land plant model systems may therefore provide an insightful evolutionary backdrop for effector–target research.
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Affiliation(s)
- Philip Carella
- University of Cambridge, Sainsbury Laboratory, Cambridge, United Kingdom
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17
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Schroeder GN. The Toolbox for Uncovering the Functions of Legionella Dot/Icm Type IVb Secretion System Effectors: Current State and Future Directions. Front Cell Infect Microbiol 2018; 7:528. [PMID: 29354599 PMCID: PMC5760550 DOI: 10.3389/fcimb.2017.00528] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 12/13/2017] [Indexed: 12/13/2022] Open
Abstract
The defective in organelle trafficking/intracellular multiplication (Dot/Icm) Type IVb secretion system (T4SS) is the essential virulence factor for the intracellular life style and pathogenicity of Legionella species. Screens demonstrated that an individual L. pneumophila strain can use the Dot/Icm T4SS to translocate an unprecedented number of more than 300 proteins into host cells, where these, so called Icm/Dot-translocated substrates (IDTS) or effectors, manipulate host cell functions to the benefit of the bacteria. Bioinformatic analysis of the pan-genus genome predicts at least 608 orthologous groups of putative effectors. Deciphering the function of these effectors is key to understanding Legionella pathogenesis; however, the analysis is challenging. Substantial functional redundancy renders classical, phenotypic screening of single gene deletion mutants mostly ineffective. Here, I review experimental approaches that were successfully used to identify, validate and functionally characterize T4SS effectors and highlight new methods, which promise to facilitate unlocking the secrets of Legionella's extraordinary weapons arsenal.
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Affiliation(s)
- Gunnar N Schroeder
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, United Kingdom
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18
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Teper D, Girija AM, Bosis E, Popov G, Savidor A, Sessa G. The Xanthomonas euvesicatoria type III effector XopAU is an active protein kinase that manipulates plant MAP kinase signaling. PLoS Pathog 2018; 14:e1006880. [PMID: 29377937 PMCID: PMC5805367 DOI: 10.1371/journal.ppat.1006880] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/08/2018] [Accepted: 01/15/2018] [Indexed: 11/19/2022] Open
Abstract
The Gram-negative bacterium Xanthomonas euvesicatoria (Xe) is the causal agent of bacterial spot disease of pepper and tomato. Xe delivers effector proteins into host cells through the type III secretion system to promote disease. Here, we show that the Xe effector XopAU, which is conserved in numerous Xanthomonas species, is a catalytically active protein kinase and contributes to the development of disease symptoms in pepper plants. Agrobacterium-mediated expression of XopAU in host and non-host plants activated typical defense responses, including MAP kinase phosphorylation, accumulation of pathogenesis-related (PR) proteins and elicitation of cell death, that were dependent on the kinase activity of the effector. XopAU-mediated cell death was not dependent on early signaling components of effector-triggered immunity and was also observed when the effector was delivered into pepper leaves by Xanthomonas campestris pv. campestris, but not by Xe. Protein-protein interaction studies in yeast and in planta revealed that XopAU physically interacts with components of plant immunity-associated MAP kinase cascades. Remarkably, XopAU directly phosphorylated MKK2 in vitro and enhanced its phosphorylation at multiple sites in planta. Consistent with the notion that MKK2 is a target of XopAU, silencing of the MKK2 homolog or overexpression of the catalytically inactive mutant MKK2K99R in N. benthamiana plants reduced XopAU-mediated cell death and MAPK phosphorylation. Furthermore, yeast co-expressing XopAU and MKK2 displayed reduced growth and this phenotype was dependent on the kinase activity of both proteins. Together, our results support the conclusion that XopAU contributes to Xe disease symptoms in pepper plants and manipulates host MAPK signaling through phosphorylation and activation of MKK2.
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Affiliation(s)
- Doron Teper
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| | | | - Eran Bosis
- Department of Biotechnology Engineering, ORT Braude College, Karmiel, Israel
| | - Georgy Popov
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| | - Alon Savidor
- The Nancy & Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Guido Sessa
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
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19
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Mares RE, Ramos MA. An amebic protein disulfide isomerase (PDI) complements the yeast PDI1 mutation but is unable to support cell viability under ER or thermal stress. FEBS Open Bio 2017; 8:49-55. [PMID: 29321956 PMCID: PMC5757170 DOI: 10.1002/2211-5463.12350] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 10/18/2017] [Accepted: 11/07/2017] [Indexed: 01/04/2023] Open
Abstract
In eukaryotic cells, protein disulfide isomerases (PDI) are oxidoreductases that catalyze the proper disulfide bond formation during protein folding. The pathobiology of the protozoan parasite Entamoeba histolytica, the causative agent of human amebiasis, depends on secretion of several virulence factors, such as pore‐forming peptides and cysteine proteinases. Although the native conformation of these factors is stabilized by disulfide bonds, there is little information regarding the molecular machinery involved in the oxidative folding of amebic proteins. Whereas testing gene function in their physiological background would be the most suitable approach, we have taken advantage of the cellular benefits offered by the yeast Saccharomyces cerevisiae (as a model of eukaryotic cell) to examine the functional role of an amebic PDI (EhPDI). As the yeast PDI homolog is essential for cell viability, a functional complementation assay was carried out to test the ability of EhPDI to circumvent the lethal phenotype of a yeast PDI1 mutant. Also, its proficiency under stressful conditions was explored by examining the survival outcome following endoplasmic reticulum (ER) stress induced by a reductant agent (DTT) or thermal stress promoted by a nonpermissive temperature (37 °C). Our results indicate that EhPDI is functionally active when physiological conditions are stable. Nonetheless, when conditions are stressful (e.g., by the accumulation of misfolded proteins in the ER compartment), its functionality is exceeded, suggesting an inability to prevent unfolding, suppress aggregation, or assist refolding of proteins. Despite the latter, our findings constitute the initial step toward determining the participation of EhPDI in cellular mechanisms related to protein homeostasis.
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Affiliation(s)
- Rosa E Mares
- Facultad de Ciencias Químicas e Ingeniería Universidad Autónoma de Baja California Tijuana Baja California México
| | - Marco A Ramos
- Facultad de Ciencias Químicas e Ingeniería Universidad Autónoma de Baja California Tijuana Baja California México
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20
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Bankapalli LK, Mishra RC, Raychaudhuri S. VopE, a Vibrio cholerae Type III Effector, Attenuates the Activation of CWI-MAPK Pathway in Yeast Model System. Front Cell Infect Microbiol 2017; 7:82. [PMID: 28373966 PMCID: PMC5357651 DOI: 10.3389/fcimb.2017.00082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 03/02/2017] [Indexed: 01/05/2023] Open
Abstract
VopE, a mitochondrial targeting T3SS effector protein of Vibrio cholerae, perturbs innate immunity by modulating mitochondrial dynamics. In the current study, ectopic expression of VopE was found to be toxic in a yeast model system and toxicity was further aggravated in the presence of various stressors. Interestingly, a VopE variant lacking predicted mitochondrial targeting sequence (MTS) also exhibited partial lethality in the yeast system. With the aid of yeast genetic tools and different stressors, we have demonstrated that VopE and its derivative VopEΔMTS modulate cell wall integrity (CWI-MAPK) signaling pathway and have identified several critical residues contributing to the lethality of VopE. Furthermore, co-expression of two effectors VopEΔMTS and VopX, interfering with the CWI-MAPK cellular pathway can partially suppress the VopX mediated yeast growth inhibition. Taken together, these results suggest that VopE alters signaling through the CWI-MAPK pathway, and demonstrates the usefulness of yeast model system to gain additional insights on the functionality of VopE.
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Affiliation(s)
- Leela K Bankapalli
- Molecular Biology and Microbial Physiology, Institute of Microbial Technology Chandigarh, India
| | - Rahul C Mishra
- Molecular Biology and Microbial Physiology, Institute of Microbial Technology Chandigarh, India
| | - Saumya Raychaudhuri
- Molecular Biology and Microbial Physiology, Institute of Microbial Technology Chandigarh, India
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21
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Puigvert M, Guarischi-Sousa R, Zuluaga P, Coll NS, Macho AP, Setubal JC, Valls M. Transcriptomes of Ralstonia solanacearum during Root Colonization of Solanum commersonii. FRONTIERS IN PLANT SCIENCE 2017; 8:370. [PMID: 28373879 PMCID: PMC5357869 DOI: 10.3389/fpls.2017.00370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/02/2017] [Indexed: 05/03/2023]
Abstract
Bacterial wilt of potatoes-also called brown rot-is a devastating disease caused by the vascular pathogen Ralstonia solanacearum that leads to significant yield loss. As in other plant-pathogen interactions, the first contacts established between the bacterium and the plant largely condition the disease outcome. Here, we studied the transcriptome of R. solanacearum UY031 early after infection in two accessions of the wild potato Solanum commersonii showing contrasting resistance to bacterial wilt. Total RNAs obtained from asymptomatic infected roots were deep sequenced and for 4,609 out of the 4,778 annotated genes in strain UY031 were recovered. Only 2 genes were differentially-expressed between the resistant and the susceptible plant accessions, suggesting that the bacterial component plays a minor role in the establishment of disease. On the contrary, 422 genes were differentially expressed (DE) in planta compared to growth on a synthetic rich medium. Only 73 of these genes had been previously identified as DE in a transcriptome of R. solanacearum extracted from infected tomato xylem vessels. Virulence determinants such as the Type Three Secretion System (T3SS) and its effector proteins, motility structures, and reactive oxygen species (ROS) detoxifying enzymes were induced during infection of S. commersonii. On the contrary, metabolic activities were mostly repressed during early root colonization, with the notable exception of nitrogen metabolism, sulfate reduction and phosphate uptake. Several of the R. solanacearum genes identified as significantly up-regulated during infection had not been previously described as virulence factors. This is the first report describing the R. solanacearum transcriptome directly obtained from infected tissue and also the first to analyze bacterial gene expression in the roots, where plant infection takes place. We also demonstrate that the bacterial transcriptome in planta can be studied when pathogen numbers are low by sequencing transcripts from infected tissue avoiding prokaryotic RNA enrichment.
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Affiliation(s)
- Marina Puigvert
- Department of Genetics, University of BarcelonaBarcelona, Spain
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
| | | | - Paola Zuluaga
- Department of Genetics, University of BarcelonaBarcelona, Spain
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
| | - Núria S. Coll
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
| | - Alberto P. Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences (CAS)Shanghai, China
| | - João C. Setubal
- Department of Biochemistry, University of São PauloSão Paulo, Brazil
| | - Marc Valls
- Department of Genetics, University of BarcelonaBarcelona, Spain
- Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain
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22
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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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23
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Popa C, Li L, Gil S, Tatjer L, Hashii K, Tabuchi M, Coll NS, Ariño J, Valls M. The effector AWR5 from the plant pathogen Ralstonia solanacearum is an inhibitor of the TOR signalling pathway. Sci Rep 2016; 6:27058. [PMID: 27257085 PMCID: PMC4891724 DOI: 10.1038/srep27058] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 05/12/2016] [Indexed: 01/31/2023] Open
Abstract
Bacterial pathogens possess complex type III effector (T3E) repertoires that are translocated inside the host cells to cause disease. However, only a minor proportion of these effectors have been assigned a function. Here, we show that the T3E AWR5 from the phytopathogen Ralstonia solanacearum is an inhibitor of TOR, a central regulator in eukaryotes that controls the switch between cell growth and stress responses in response to nutrient availability. Heterologous expression of AWR5 in yeast caused growth inhibition and autophagy induction coupled to massive transcriptomic changes, unmistakably reminiscent of TOR inhibition by rapamycin or nitrogen starvation. Detailed genetic analysis of these phenotypes in yeast, including suppression of AWR5-induced toxicity by mutation of CDC55 and TPD3, encoding regulatory subunits of the PP2A phosphatase, indicated that AWR5 might exert its function by directly or indirectly inhibiting the TOR pathway upstream PP2A. We present evidence in planta that this T3E caused a decrease in TOR-regulated plant nitrate reductase activity and also that normal levels of TOR and the Cdc55 homologues in plants are required for R. solanacearum virulence. Our results suggest that the TOR pathway is a bona fide T3E target and further prove that yeast is a useful platform for T3E function characterisation.
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Affiliation(s)
- Crina Popa
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
- Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Liang Li
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - Sergio Gil
- Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Laura Tatjer
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Catalonia, Spain
| | - Keisuke Hashii
- Laboratory of Applied Molecular and Cell Biology, Kagawa University, Kagawa, Japan
| | - Mitsuaki Tabuchi
- Laboratory of Applied Molecular and Cell Biology, Kagawa University, Kagawa, Japan
| | - Núria S. Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Catalonia, Spain
| | - Marc Valls
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
- Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain
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