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Wong Z, Ong EBB. 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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Affiliation(s)
- ZhenPei Wong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800 USM, Malaysia
| | - Eugene Boon Beng Ong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800 USM, Malaysia.
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Huang B, Zhu Z, Dai Y, Yan C, Xu J, Sun L, Zhang Q, An X, Lai F. Characterization of translocon proteins in the type III secretion system of Lawsonia intracellularis. Vet Res 2023; 54:108. [PMID: 37993950 PMCID: PMC10664548 DOI: 10.1186/s13567-023-01243-0] [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: 08/12/2023] [Accepted: 10/24/2023] [Indexed: 11/24/2023] Open
Abstract
Lawsonia intracellularis, the etiologic agent of proliferative enteropathy (PE), is an obligate intracellular Gram-negative bacterium possessing a type III secretion system (T3SS), which enables the pathogen to translocate effector proteins into targeted host cells to modulate their functions. T3SS is a syringe-like apparatus consisting of a base, an extracellular needle, a tip, and a translocon. The translocon proteins assembled by two hydrophobic membrane proteins can form pores in the host-cell membrane, and therefore play an essential role in the function of T3SS. To date, little is known about the T3SS and translocon proteins of L. intracellularis. In this study, we first analyzed the conservation of the T3S apparatus between L. intracellularis and Yersinia, and characterized the putative T3S hydrophobic major translocon protein LI1158 and minor translocon protein LI1159 in the L. intracellularis genome. Then, by using Yersinia pseudotuberculosis as a surrogate system, we found that the full-length LI1158 and LI1159 proteins, but not the putative class II chaperone LI1157, were secreted in a - Ca2+ and T3SS-dependent manner and the secretion signal was located at the N terminus (aa 1-40). Furthermore, yeast-two hybrid experiments revealed that LI1158 and LI1159 could self-interact, and LI1159 could interact with LI1157. However, unlike CPn0809 and YopB, which are the major hydrophobic translocon proteins of the T3SS of C. pneumoniae and Yersinia, respectively, full-length LI1158 was non-toxic to both yeast and Escherichia coli cells, but full-length LI1159 showed certain toxicity to E. coli cells. Taken together, despite some differences from the findings in other bacteria, our results demonstrate that LI1158 and LI1159 may be the translocon proteins of L. intracellularis T3SS, and probably play important roles in the translocation of effector proteins at the early pathogen infection stage.
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Affiliation(s)
- Beibei Huang
- School of Bioscience and Bioengineering, Nanchang Key Laboratory of Fermentation Application Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Zihe Zhu
- School of Bioscience and Bioengineering, Nanchang Key Laboratory of Fermentation Application Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Yimin Dai
- School of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Chengxian Yan
- School of Bioscience and Bioengineering, Nanchang Key Laboratory of Fermentation Application Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Jingyu Xu
- School of Bioscience and Bioengineering, Nanchang Key Laboratory of Fermentation Application Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Lingling Sun
- School of Bioscience and Bioengineering, Nanchang Key Laboratory of Fermentation Application Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Qinghua Zhang
- School of Bioscience and Bioengineering, Nanchang Key Laboratory of Fermentation Application Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Xuejiao An
- School of Bioscience and Bioengineering, Nanchang Key Laboratory of Fermentation Application Technology, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Fenju Lai
- Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, Nanchang, Jiangxi, China.
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Karuppannan AK. Editorial: Lawsonia intracellularis: a problem well understood is a problem half solved. Front Vet Sci 2023; 10:1203702. [PMID: 37205227 PMCID: PMC10185883 DOI: 10.3389/fvets.2023.1203702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 05/21/2023] Open
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Xiao N, Li J, Li M, Zhou H, Lin H, Fan H. Isolation and In Vitro cultivation of Lawsonia intracellularis from China. Vet Microbiol 2022; 270:109457. [PMID: 35609389 DOI: 10.1016/j.vetmic.2022.109457] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 04/02/2022] [Accepted: 05/09/2022] [Indexed: 11/20/2022]
Abstract
Lawsonia intracellularis is an obligate intracellular bacterium that cannot be cultured by conventional bacteriological methods. Pigs infected with L. intracellularis suffer from decreased daily weight gain and poor feed conversion ratio. China is a large producer of pigs, but epidemiological investigation data of L. intracellularis has not been obtained in recent years. Additionally, there is no information about a L. intracellularis strain being successfully isolated and established in cell culture in China, and the above shortcomings limit understanding of the pathogenesis of L. intracellularis and alternative prevention and control methods. The aims of this study were to estimate the seroprevalence of L. intracellularis antibodies in eight major pig-producing provinces in China during 2019-2020, to isolate L. intracellularis from infected intestines and then to establish an infection model of L. intracellularis in mice. Our results showed that of the 3586 serum samples, 2837 (79.1%, 95% CI: 77.7%, 80.4%) were seropositive for the L. intracellularis antibody. Subsequently, the L. intracellularis strain LJS19051 from China was successfully isolated and established in cell culture. Furthermore, L. intracellularis DNA and antibodies could be detected in the feces and serum samples of infected mice, respectively. Moreover, infected crypts showed typical proliferative enteropathies (PE) lesions and L. intracellularis antigen was detected in infected mice by immunofluorescence at 28 days post inoculation. The results indicated that the new L. intracellularis strain LJS19051 was obtained and could successfully proliferate in ICR mice.
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Affiliation(s)
- Ning Xiao
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiannan Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Minxue Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Hong Zhou
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Huixing Lin
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Hongjie Fan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
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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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Xiao N, Li J, Li M, Hu Y, Lin H, Fan H. Preparation and Characterization of a New Monoclonal Antibody Specific Against Lawsonia intracellularis and Its Application in Indirect Immunofluorescence and Immunocytochemistry Assay. Front Vet Sci 2021; 8:753610. [PMID: 34912873 PMCID: PMC8667467 DOI: 10.3389/fvets.2021.753610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/21/2021] [Indexed: 12/31/2022] Open
Abstract
Proliferative enteropathy (PE) is an infectious enteric disease caused by Lawsonia intracellularis (L. intracellularis) and is endemic in pig herds worldwide. However, a L. intracellularis-specific monoclonal antibody plays an important role in the evaluation of L. intracellularis infection in vitro. Therefore, the objective of this study was to produce and identify the characteristics of a new monoclonal antibody against the outer membrane protein (Omp2) of L. intracellularis and apply it in an indirect immunofluorescence assay (IFA) and immunocytochemistry (IHC). The results indicated that three highly specific monoclonal antibodies against the Omp2 protein (4D9, 3G2, and 7G5) of L. intracellularis were obtained by using purified Omp2 as an immunogen, the titers of ascitic fluids of 4D9, 3G2, and 7G5 cells were 1:2,048,000, 1:512,000, and 1:256,000, respectively. IFA analysis showed that the 4D9, 3G2, and 7G5 have no cross-reactivity with other enteric bacteria commonly found in the ilea of pigs or closely related to L. intracellularis, such as Desulfovibrio, Bilophila wadsworthia (B. wadsworthia), Salmonella choleraesuis (S. choleraesuis), Salmonella typhimurium (S. typhimurium), Escherichia coli (E. coli), and Brachyspira hyodysenteriae (B. hyodysenteriae). IFA and IHC results indicated that the monoclonal antibodies can be successfully used as primary antibodies to detect L. intracellularis in infected cells and in the crypt of the ileum from infected tissues of PE. Our findings suggested that the new monoclonal antibody specific against L. intracellularis will be useful for the evaluation of L. intracellularis infection in vivo and in vitro.
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Affiliation(s)
- Ning Xiao
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jiannan Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Minxue Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yuting Hu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Huixing Lin
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Hongjie Fan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
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