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Hwang IS, Oh EJ, Oh CS. A novel virulence gene, cviA1 of Clavibacter michiganensis for necrosis development in the Nicotiana benthamiana plant. Microbiol Res 2024; 285:127743. [PMID: 38733725 DOI: 10.1016/j.micres.2024.127743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/06/2024] [Accepted: 04/30/2024] [Indexed: 05/13/2024]
Abstract
Clavibacter michiganensis is a Gram-positive bacterium that causes diverse disease symptoms in tomatoes and Nicotiana benthamiana, a surrogate host plant, including canker, blister lesions, and wilting. Previously, we reported that C. michiganensis also causes necrosis in N. benthamiana leaves. Here, to identify novel virulence genes of C. michiganensis required for necrosis development in N. benthamiana leaves, we screened 1,862 transposon-inserted mutants and identified a mutant strain that exhibited weak and delayed necrosis, whereas there was no discernible difference in blister lesions, canker, or wilting symptoms. Notably, this mutant caused canker similar to that of the wild-type strain, but caused mild wilting in tomato. This mutant carried a transposon in a chromosomal gene, called Clavibactervirulence gene A1 (cviA1). CviA1 encodes a 180-amino acid protein with a signal peptide (SP) at the N-terminus and two putative transmembrane domains (TMs) at the C-terminus. Interestingly, deletion of the SP or the C-terminus, including the two putative TMs, in CviA1 failed to restore full necrosis in the mutant, highlighting the importance of protein secretion and the putative TMs for necrosis. A paralog of cviA1, cviA2 is located on the large plasmid pCM2 of C. michiganensis. Despite its high similarity to cviA1, the introduction of cviA2 into the cviA1 mutant strain did not restore virulence. Similarly, the introduction of cviA1 into the Clavibacter capsici type strain PF008, which initially lacks cviA1, did not enhance necrosis symptoms. These results reveals that the chromosomal cviA1 gene in C. michiganensis plays an important role in necrosis development in N. benthamiana leaves.
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Affiliation(s)
- In Sun Hwang
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, the Republic of Korea
| | - Eom-Ji Oh
- Plant Immunity Research Center, Seoul National University, Seoul 08826, the Republic of Korea
| | - Chang-Sik Oh
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, the Republic of Korea; Plant Immunity Research Center, Seoul National University, Seoul 08826, the Republic of Korea; Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, the Republic of Korea; Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826, the Republic of Korea.
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Gershberg J, Morhaim M, Rostrovsky I, Eichler J, Sal-Man N. The sequence of events of enteropathogenic E. coli's type III secretion system translocon assembly. iScience 2024; 27:109108. [PMID: 38375228 PMCID: PMC10875159 DOI: 10.1016/j.isci.2024.109108] [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: 08/23/2023] [Revised: 12/17/2023] [Accepted: 01/31/2024] [Indexed: 02/21/2024] Open
Abstract
Many bacterial pathogens employ the type III secretion system (T3SS), a specialized complex that transports effector proteins that manipulate various cellular processes. The T3SS forms a translocon pore within the host-cell membrane consisting of two secreted proteins that transition from a soluble state into a transmembrane complex. Still, the exact sequence of events leading to the formation of a membranous functional pore remains uncertain. Here, we utilized the translocon proteins of enteropathogenic E. coli (EPEC) to investigate the sequence of those steps leading to translocon assembly, including self-oligomerization, hetero-oligomerization, interprotein interaction, and membrane insertion. We found that in EPEC, EspD (SctE) plays a dominant role in pore formation as it assembles into an oligomeric state, regardless of pH, membrane contact, or the presence of EspB (SctB). Subsequently, EspB subunits integrate into EspD homo-oligomers to create EspB-EspD hetero-oligomers that adopt a transmembrane orientation to create a functional pore complex.
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Affiliation(s)
- Jenia Gershberg
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - May Morhaim
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Irina Rostrovsky
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Neta Sal-Man
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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Elias-Mordechai M, David N, Oren S, Georgia Pelah M, Jopp J, Fichtman B, Harel A, Berkovich R, Sal-Man N. A single filament biomechanical study of the enteropathogenic Escherichia coli Type III secretion system reveals a high elastic aspect ratio. NANOSCALE 2023; 15:15027-15037. [PMID: 37668452 DOI: 10.1039/d3nr01953e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Type III secretion systems (T3SSs) are syringe-like protein complexes used by some of the most harmful bacterial pathogens to infect host cells. While the T3SS filament, a long hollow conduit that bridges between bacteria and host cells, has been characterized structurally, very little is known about its physical properties. These filaments should endure shear and normal stresses imposed by the viscous mucosal flow during infection within the intestinal tract. We used atomic force microscopy (AFM) to probe the longitudinal and radial mechanical response of individual T3SS filaments by pulling on filaments extending directly from bacterial surfaces and later pressing into filaments that were detached from the bacteria. The measured longitudinal elastic moduli were higher by about two orders of magnitude than the radial elastic moduli. These proportions are commensurate with the role of the T3SS filament, which requires horizontal flexibility while maintaining its structural integrity to withstand intense stresses during infection.
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Affiliation(s)
- Moran Elias-Mordechai
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Nofar David
- Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Sonia Oren
- Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Maya Georgia Pelah
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Jürgen Jopp
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Boris Fichtman
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Amnon Harel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Ronen Berkovich
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Neta Sal-Man
- Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
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Braverman D, Gershberg J, Sal-Man N. The transmembrane domains of the type III secretion system effector Tir are involved in its secretion and cellular activities. Front Cell Infect Microbiol 2023; 13:1103552. [PMID: 36864885 PMCID: PMC9971567 DOI: 10.3389/fcimb.2023.1103552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 02/01/2023] [Indexed: 02/16/2023] Open
Abstract
Introduction Enteropathogenic Escherichia coli (EPEC) is a diarrheagenic pathogen and one of the major causes of gastrointestinal illness in developing countries. EPEC, similar to many other Gram-negative bacterial pathogens, possesses essential virulence machinery called the type III secretion system (T3SS) that enables the injection of effector proteins from the bacteria into the host cytoplasm. Of these, the translocated intimin receptor (Tir) is the first effector to be injected, and its activity is essential for the formation of attaching and effacing lesions, the hallmark of EPEC colonization. Tir belongs to a unique group of transmembrane domain (TMD)-containing secreted proteins, which have two conflicting destination indications, one for bacterial membrane integration and another for protein secretion. In this study, we examined whether TMDs participate in the secretion, translocation, and function of Tir in host cells. Methods We created Tir TMD variants with the original or alternative TMD sequence. Results We found that the C-terminal TMD of Tir (TMD2) is critical for the ability of Tir to escape integration into the bacterial membrane. However, the TMD sequence was not by itself sufficient and its effect was context-dependent. Moreover, the N-terminal TMD of Tir (TMD1) was important for the postsecretion function of Tir at the host cell. Discussion Taken together, our study further supports the hypothesis that the TMD sequences of translocated proteins encode information crucial for protein secretion and their postsecretion function.
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Affiliation(s)
- Dor Braverman
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Jenia Gershberg
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Chen P, Goldberg MB. Recent insights into type-3 secretion system injectisome structure and mechanism of human enteric pathogens. Curr Opin Microbiol 2023; 71:102232. [PMID: 36368294 PMCID: PMC10510281 DOI: 10.1016/j.mib.2022.102232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/06/2022] [Accepted: 10/19/2022] [Indexed: 11/10/2022]
Abstract
Type-3 secretion system injectisomes are multiprotein complexes that translocate bacterial effector proteins from the cytoplasm of gram-negative bacteria directly into the cytosol of eukaryotic host cells. These systems are present in more than 30 bacterial species, including numerous human, animal, and plant pathogens. We review recent discoveries of structural and molecular mechanisms of effector protein translocation through the injectisomes and recent advances in the understanding of mechanisms of activation of effector protein secretion.
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Affiliation(s)
- Poyin Chen
- Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Marcia B Goldberg
- Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Microbiology, Harvard Medical School, Boston, MA, USA; Broad Institute, Cambridge, MA, USA.
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Zhao T, Yang B, Li H, Qian A, Cong W, Sun W, Kang Y. Essential role of ascO for virulence of Aeromonas veronii and inducing apoptosis. JOURNAL OF FISH DISEASES 2022; 45:1477-1489. [PMID: 35749548 DOI: 10.1111/jfd.13676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/06/2022] [Accepted: 06/10/2022] [Indexed: 06/15/2023]
Abstract
Aeromonas veronii is a significant pathogen that is capable of infecting humans, animals, and aquatic animals. The type III secretion system (T3SS) is intimately associated with bacterial pathogenicity. The ascO gene is an important core component of T3SS in A. veronii, but its function is still unclear. The ascO gene of A. veronii TH0426 was deleted by using the pRE112 suicide plasmid to study its function. The study results showed that the ability of ∆ascO to adhere and invade EPC cells was significantly reduced by 1.28 times. The toxicity of the mutant strain ΔascO to EPC cells was consistently significantly lower than wild-type strain TH0426 at 1, 2, and 4 h. The LD50 values of ∆ascO against zebrafish and Carassius auratus (C. auratus) were 53 and 15 times that of the wild-type strain. In addition, the bacterial load of the mutant strain ΔascO in blood, heart, liver, and spleen was lower than wild-type strain TH0426. The Hoechst staining showed that the apoptotic degree of EPC cells induced by the mutant strain ΔascO was lower than that of the wild-type strain TH0426. Furthermore, real-time quantitative PCR (RT-qPCR) analysis revealed lower expression levels of pro-apoptotic genes (including cytC, cas3, cas9, TNF-α, and IL-1β) in C. auratus tissues infected with the mutant strain ΔascO compared to the wild-type strain TH0426. The results of in vivo and in vitro experiments have shown that ascO gene mutation can reduce the adhesion and toxicity of A. veronii to EPC and reduce the level of apoptosis induced by A. veronii. As a result, these insights will help further elucidate the function of the ascO gene and thus contribute to understanding the pathogenesis of A. veronii.
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Affiliation(s)
- Tong Zhao
- College of Veterinary Medicine/College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
- Marine College, Shandong University, Weihai, China
| | - Bintong Yang
- Marine College, Shandong University, Weihai, China
| | - Hongjin Li
- College of Veterinary Medicine/College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
- Marine College, Shandong University, Weihai, China
| | - Aidong Qian
- College of Veterinary Medicine/College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
| | - Wei Cong
- Marine College, Shandong University, Weihai, China
| | - Wuwen Sun
- College of Veterinary Medicine/College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
| | - Yuanhuan Kang
- College of Veterinary Medicine/College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
- Marine College, Shandong University, Weihai, China
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