1
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Han J, Balasubramanian I, Flores JA, Bandyopadhyay S, Yang J, Liu Y, Singh R, Setty P, Kiela P, Ferraris R, Gao N. Intestinal lysozyme engagement of Salmonella Typhimurium stimulates the release of barrier-impairing InvE and Lpp1. J Biol Chem 2024; 300:107424. [PMID: 38823640 PMCID: PMC11255904 DOI: 10.1016/j.jbc.2024.107424] [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: 02/28/2024] [Revised: 05/06/2024] [Accepted: 05/17/2024] [Indexed: 06/03/2024] Open
Abstract
Lysozyme is a β-1,4-glycosidase that hydrolyzes the polysaccharide backbone of bacterial cell walls. With an additional bactericidal function mediated by a separate protein domain, lysozyme is considered a uniquely important antimicrobial molecule contributing to the host's innate immune response to infection. Elevated lysozyme production is found in various inflammatory conditions while patients with genetic risks for inflammatory bowel diseases demonstrate abnormal lysozyme expression, granule packaging, and secretion in Paneth cells. However, it remains unclear how a gain- or loss-of-function in host lysozyme may impact the host inflammatory responses to pathogenic infection. We challenged Lyz1-/- and ectopic Lyz1-expressing (Villin-Lyz1TG) mice with S. Typhimurium and then comprehensively assessed the inflammatory disease progression. We conducted proteomics analysis to identify molecules derived from human lysozyme-mediated processing of live Salmonella. We examined the barrier-impairing effects of these identified molecules in human intestinal epithelial cell monolayer and enteroids. Lyz1-/- mice are protected from infection in terms of morbidity, mortality, and barrier integrity, whereas Villin-Lyz1TG mice demonstrate exacerbated infection and inflammation. The growth and invasion of Salmonella in vitro are not affected by human or chicken lysozyme, whereas lysozyme encountering of live Salmonella stimulates the release of barrier-disrupting factors, InvE-sipC and Lpp1, which directly or indirectly impair the tight junctions. The direct engagement of host intestinal lysozyme with an enteric pathogen such as Salmonella promotes the release of virulence factors that are barrier-impairing and pro-inflammatory. Controlling lysozyme function may help alleviate the inflammatory progression.
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Affiliation(s)
- Jiangmeng Han
- Department of Biological Sciences, Rutgers University, Newark, New Jersey, USA
| | | | - Juan A Flores
- Department of Biological Sciences, Rutgers University, Newark, New Jersey, USA
| | | | - Jiaxing Yang
- Department of Biological Sciences, Rutgers University, Newark, New Jersey, USA
| | - Yue Liu
- Department of Biological Sciences, Rutgers University, Newark, New Jersey, USA
| | - Rajbir Singh
- Department of Biological Sciences, Rutgers University, Newark, New Jersey, USA
| | - Prashanth Setty
- Department of Pediatrics, Daniel Cracchiolo Institute for Pediatric Autoimmune Disease Research, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA
| | - Pawel Kiela
- Department of Pediatrics, Daniel Cracchiolo Institute for Pediatric Autoimmune Disease Research, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA
| | - Ronaldo Ferraris
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
| | - Nan Gao
- Department of Biological Sciences, Rutgers University, Newark, New Jersey, USA; Department of Pharmacology, Physiology, and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA.
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2
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Jiang Z, Li D, Liu Z, Dong X, Liu Z, Cui D, Yan S, Zhu L. Genomic typing and virulence gene profile analysis of Salmonella Derby from different sources. Microb Pathog 2023; 182:106248. [PMID: 37423493 DOI: 10.1016/j.micpath.2023.106248] [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: 01/15/2023] [Revised: 07/07/2023] [Accepted: 07/07/2023] [Indexed: 07/11/2023]
Abstract
Salmonella enterica serovar Derby (S. Derby) is one of the most common Salmonella serovars which can infect poultry, swine, and humans. With the reduction of the sequencing cost and the improvement of sequencing technology, whole genome sequencing (WGS) has become an important method for bacterial determination, molecular investigation, and pathogenic tracing analysis. In this study, we investigated S. Derby isolates from different sources in China using in-silico multilocus sequence typing (MLST), core genome MLST (cgMLST) and whole genome MLST (wgMLST) analysis based on WGS. The results showed that 21 S. Derby strains were divided into 3 STs using MLST analysis, including ST40 (n = 19, accounting for 90.48%), ST71 (n = 1, accounting for 4.76%) and ST8016 (n = 1, accounting for 4.76%). cgMLST and wgMLST analysis categorized the tested strains into 13 cgSTs and 21 wgSTs, respectively. The minimum spanning trees of cgMLST and wgMLST both divided these strains into 3 clusters and 4 singletons. In addition, virulence gene profiles of S. Derby isolates were also analyzed, and a total of 174 virulence genes belonged to 8 categories were identified. In summary, we studied genomic typing, phylogenetic relationship and virulence gene profiles of S. Derby strains from different sources in China. These findings were beneficial for the epidemiology and pathogenesis of Salmonella.
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Affiliation(s)
- Zhaoxu Jiang
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Donghui Li
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Zhenhai Liu
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Xiaorui Dong
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Zijun Liu
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
| | - Daoshi Cui
- Qilu Animal Health Products Co., Ltd, Jinan, 250100, China
| | - Shigan Yan
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
| | - Liping Zhu
- School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
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3
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Transcriptional insight into the effect of benzalkonium chloride on resistance and virulence potential in Salmonella Typhimurium. Microbiol Res 2023; 266:127240. [DOI: 10.1016/j.micres.2022.127240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/26/2022] [Accepted: 10/12/2022] [Indexed: 11/27/2022]
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4
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Singh N, Kronenberger T, Eipper A, Weichel F, Franz-Wachtel M, Macek B, Wagner S. Conserved Salt Bridges Facilitate Assembly of the Helical Core Export Apparatus of a Salmonella enterica Type III Secretion System. J Mol Biol 2021; 433:167175. [PMID: 34303721 DOI: 10.1016/j.jmb.2021.167175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 07/13/2021] [Accepted: 07/14/2021] [Indexed: 11/27/2022]
Abstract
Virulence-associated type III secretion systems (T3SS) are utilized by Gram negative bacterial pathogens for injection of effector proteins into eukaryotic host cells. The transmembrane export apparatus at the core of T3SS is composed of a unique helical complex of the hydrophobic proteins SctR, SctS, SctT, and SctU. These components comprise a number of highly conserved charged residues within their hydrophobic domains. The structure of the closed state of the core complex SctR5S4T1 revealed that several of these residues form inter- and intramolecular salt bridges, some of which have to be broken for pore opening. Mutagenesis of individual residues was shown to compromise assembly or secretion of both, the virulence-associated and the related flagellar T3SS. However, the exact role of these conserved charged residues in the assembly and function of T3SS remains elusive. Here we performed an in-depth mutagenesis analysis of these residues in the T3SS of Salmonella Typhimurium, coupled to blue native PAGE, in vivo photocrosslinking and luciferase-based secretion assays. Our data show that these conserved salt bridges are not critical for assembly of the respective protein but rather facilitate the incorporation of the following subunit into the assembling complex. Our data also indicate that these conserved charged residues are critical for type III-dependent secretion and reveal a functional link between SctSE44 and SctTR204 and the cytoplasmic domain of SctU in gating the T3SS injectisome. Overall, our analysis provides an unprecedented insight into the delicate requirements for the assembly and function of the machinery at the core of T3SS.
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Affiliation(s)
- Nidhi Singh
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany
| | - Thales Kronenberger
- University Hospital Tübingen, Department of Internal Medicine VIII, Tübingen, Germany; School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70211 Kuopio, Finland
| | - Andrea Eipper
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany
| | - Felix Weichel
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany; Partner-site Tübingen, German Center for Infection Research (DZIF), Tübingen, Germany
| | | | - Boris Macek
- Excellence Cluster "Controlling Microbes to Fight Infections" (CMFI), Tübingen, Germany; Proteome Center Tübingen, University of Tübingen, Tübingen, Germany
| | - Samuel Wagner
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany; Excellence Cluster "Controlling Microbes to Fight Infections" (CMFI), Tübingen, Germany; Partner-site Tübingen, German Center for Infection Research (DZIF), Tübingen, Germany.
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5
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Greene AR, Owen KA, Casanova JE. Salmonella Typhimurium manipulates macrophage cholesterol homeostasis through the SseJ-mediated suppression of the host cholesterol transport protein ABCA1. Cell Microbiol 2021; 23:e13329. [PMID: 33742761 DOI: 10.1111/cmi.13329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 12/27/2022]
Abstract
Upon infection of host cells, Salmonella enterica serovar Typhimurium resides in a modified-endosomal compartment referred to as the Salmonella-containing vacuole (SCV). SCV biogenesis is driven by multiple effector proteins translocated through two type III secretion systems (T3SS-1 and T3SS-2). While many host proteins targeted by these effector proteins have been characterised, the role of host lipids in SCV dynamics remains poorly understood. Previous studies have shown that S. Typhimurium infection in macrophages leads to accumulation of intracellular cholesterol, some of which concentrates in and around SCVs; however, the underlying mechanisms remain unknown. Here, we show that S. Typhimurium utilises the T3SS-2 effector SseJ to downregulate expression of the host cholesterol transporter ABCA1 in macrophages, leading to a ~45% increase in cellular cholesterol. Mechanistically, SseJ activates a signalling cascade involving the host kinases FAK and Akt to suppress Abca1 expression. Mutational inactivation of SseJ acyltransferase activity, silencing FAK, or inhibiting Akt prevents Abca1 downregulation and the corresponding accumulation of cholesterol during infection. Importantly, RNAi-mediated silencing of ABCA1 rescued bacterial survival in FAK-deficient macrophages, suggesting that Abca1 downregulation and cholesterol accumulation are important for intracellular survival.
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Affiliation(s)
- Adam R Greene
- Department of Microbiology, University of Virginia Health System, Charlottesville, Virginia, USA
| | - Katherine A Owen
- Department of Cell Biology, University of Virginia Health System, Charlottesville, Virginia, USA.,Ampel Biosolutions, Charlottesville, Virginia, USA
| | - James E Casanova
- Department of Microbiology, University of Virginia Health System, Charlottesville, Virginia, USA.,Department of Cell Biology, University of Virginia Health System, Charlottesville, Virginia, USA
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6
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A Reporter System for Fast Quantitative Monitoring of Type 3 Protein Secretion in Enteropathogenic E. coli. Microorganisms 2020; 8:microorganisms8111786. [PMID: 33202599 PMCID: PMC7696366 DOI: 10.3390/microorganisms8111786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 12/16/2022] Open
Abstract
The type 3 secretion system is essential for pathogenesis of several human and animal Gram-negative bacterial pathogens. The T3SS comprises a transmembrane injectisome, providing a conduit from the bacterial cytoplasm to the host cell cytoplasm for the direct delivery of effectors (including toxins). Functional studies of T3SS commonly monitor the extracellular secretion of proteins by SDS-PAGE and western blot analysis, which are slow and semi-quantitative in nature. Here, we describe an enzymatic reporter-based quantitative and rapid in vivo assay for T3SS secretion studies in enteropathogenic E. coli (EPEC). The assay monitors the secretion of the fusion protein SctA-PhoA through the injectisome based on a colorimetric assay that quantifies the activity of alkaline phosphatase. We validated the usage of this reporter system by following the secretion in the absence of various injectisome components, including domains of the gatekeeper essential for T3SS function. This platform can now be used for the isolation of mutations, functional analysis and anti-virulence compound screening.
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7
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Miletic S, Goessweiner-Mohr N, Marlovits TC. The Structure of the Type III Secretion System Needle Complex. Curr Top Microbiol Immunol 2020; 427:67-90. [PMID: 31667599 DOI: 10.1007/82_2019_178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The type III secretion system (T3SS) is an essential virulence factor of many pathogenic bacterial species including Salmonella, Yersinia, Shigella and enteropathogenic Escherichia coli (EPEC). It is an intricate molecular machine that spans the bacterial membranes and injects effector proteins into target host cells, enabling bacterial infection. The T3SS needle complex comprises of proteinaceous rings supporting a needle filament which extends out into the extracellular environment. It serves as the central conduit for translocating effector proteins. Multiple laboratories have dedicated a remarkable effort to decipher the structure and function of the needle complex. A combination of structural biology techniques such as cryo-electron microscopy (cryoEM), X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy and computer modelling have been utilized to study different structural components at progressively higher resolutions. This chapter will provide an overview of the structural details of the T3SS needle complex, shedding light on this essential component of this fascinating bacterial system.
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Affiliation(s)
- Sean Miletic
- Center for Structural Systems Biology, Institute for Structural and Systems Biology, Universitätsklinikum Hamburg-Eppendorf, 85 Notkestraße, Hamburg, 22607, Germany
| | | | - Thomas C Marlovits
- Center for Structural Systems Biology, Institute for Structural and Systems Biology, Universitätsklinikum Hamburg-Eppendorf, 85 Notkestraße, Hamburg, 22607, Germany.
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8
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Guo Y, Gu D, Huang T, Cao L, Zhu X, Zhou Y, Wang K, Kang X, Meng C, Jiao X, Pan Z. Essential role of Salmonella Enteritidis DNA adenine methylase in modulating inflammasome activation. BMC Microbiol 2020; 20:226. [PMID: 32723297 PMCID: PMC7389876 DOI: 10.1186/s12866-020-01919-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 07/21/2020] [Indexed: 01/08/2023] Open
Abstract
Background Salmonella Enteritidis (SE) is one of the major foodborne zoonotic pathogens of worldwide importance which can induce activation of NLRC4 and NLRP3 inflammasomes during infection. Given that the inflammasomes play an essential role in resisting bacterial infection, Salmonella has evolved various strategies to regulate activation of the inflammasome, most of which largely remain unclear. Results A transposon mutant library in SE strain C50336 was screened for the identification of the potential factors that regulate inflammasome activation. We found that T3SS-associated genes invC, prgH, and spaN were required for inflammasome activation in vitro. Interestingly, C50336 strains with deletion or overexpression of Dam were both defective in activation of caspase-1, secretion of IL-1β and phosphorylation of c-Jun N-terminal kinase (Jnk). Transcriptome sequencing (RNA-seq) results showed that most of the differentially expressed genes and enriched KEGG pathways between the C50336-VS-C50336Δdam and C50336-VS-C50336::dam groups overlapped, which includes multiple signaling pathways related to the inflammasome. C50336Δdam and C50336::dam were both found to be defective in suppressing the expression of several anti-inflammasome factors. Moreover, overexpression of Dam in macrophages by lentiviral infection could specifically enhance the activation of NLRP3 inflammasome independently via promoting the Jnk pathway. Conclusions These data indicated that Dam was essential for modulating inflammasome activation during SE infection, there were complex and dynamic interplays between Dam and the inflammasome under different conditions. New insights were provided about the battle between SE and host innate immunological mechanisms.
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Affiliation(s)
- Yaxin Guo
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Dan Gu
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Tingting Huang
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Liyan Cao
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Xinyu Zhu
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Yi Zhou
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Kangru Wang
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Xilong Kang
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Chuang Meng
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China.,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China.,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China
| | - Xinan Jiao
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China. .,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China. .,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China. .,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China.
| | - Zhiming Pan
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China. .,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China. .,Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of A griculture of China, Yangzhou University, Yangzhou, Jiangsu, China. .,Joint International Research Laboratory of Agriculture and Agri-product Safety of the Ministry of Education, Yangzhou University, Yangzhou, Jiangsu, China.
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9
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Giovagnoni G, Rossi B, Tugnoli B, Ghiselli F, Bonetti A, Piva A, Grilli E. Thymol and Carvacrol Downregulate the Expression of Salmonella typhimurium Virulence Genes during an In Vitro Infection on Caco-2 Cells. Microorganisms 2020; 8:microorganisms8060862. [PMID: 32517327 PMCID: PMC7355688 DOI: 10.3390/microorganisms8060862] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/04/2020] [Accepted: 06/06/2020] [Indexed: 11/16/2022] Open
Abstract
Salmonella typhimurium is one of the major bacteria responsible for gastroenteritis in humans caused by foodborne pathogens. As pork is one of the main routes of transmission, bioactive compounds used as feed additives may be an important strategy to control Salmonella typhimurium. The aim of this study was to assess the antimicrobial activity of several organic acids and nature identical compounds against Salmonella typhimurium ATCC®® 6994™. Moreover, the effect of sub-lethal concentrations of thymol and carvacrol in counteracting a Salmonella typhimurium in vitro infection on Caco-2 cells was evaluated, focusing on the maintenance of the epithelial barrier and the alteration of Salmonella virulence genes. The results showed a protective effect of the compounds on the integrity of the intestinal monolayer, improving transepithelial electrical resistance and bacterial translocation compared to the non-treated cells. A real-time PCR study highlighted a significant downregulation of the main virulence genes of Salmonella (hilA, prgH, invA, sipA, sipC, sipD, sopB, sopE2). These findings indicate that thymol and carvacrol could be good candidates for the control of Salmonella typhimurium in pigs.
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Affiliation(s)
- Giulia Giovagnoni
- DIMEVET, Dipartimento di Scienze Mediche Veterinarie, Università di Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia (BO), Italy; (G.G.); (F.G.); (A.B.); (A.P.)
| | - Barbara Rossi
- Vetagro S.p.A., via Porro 2, 42124 Reggio Emilia, Italy; (B.R.); (B.T.)
| | - Benedetta Tugnoli
- Vetagro S.p.A., via Porro 2, 42124 Reggio Emilia, Italy; (B.R.); (B.T.)
| | - Federico Ghiselli
- DIMEVET, Dipartimento di Scienze Mediche Veterinarie, Università di Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia (BO), Italy; (G.G.); (F.G.); (A.B.); (A.P.)
| | - Andrea Bonetti
- DIMEVET, Dipartimento di Scienze Mediche Veterinarie, Università di Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia (BO), Italy; (G.G.); (F.G.); (A.B.); (A.P.)
| | - Andrea Piva
- DIMEVET, Dipartimento di Scienze Mediche Veterinarie, Università di Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia (BO), Italy; (G.G.); (F.G.); (A.B.); (A.P.)
- Vetagro S.p.A., via Porro 2, 42124 Reggio Emilia, Italy; (B.R.); (B.T.)
| | - Ester Grilli
- DIMEVET, Dipartimento di Scienze Mediche Veterinarie, Università di Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia (BO), Italy; (G.G.); (F.G.); (A.B.); (A.P.)
- Vetagro Inc., 116 W. Jackson Blvd., Suite #320, Chicago, IL 60604, USA
- Correspondence:
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10
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Pfister SP, Schären OP, Beldi L, Printz A, Notter MD, Mukherjee M, Li H, Limenitakis JP, Werren JP, Tandon D, Cuenca M, Hagemann S, Uster SS, Terrazos MA, Gomez de Agüero M, Schürch CM, Coelho FM, Curtiss R, Slack E, Balmer ML, Hapfelmeier S. Uncoupling of invasive bacterial mucosal immunogenicity from pathogenicity. Nat Commun 2020; 11:1978. [PMID: 32332737 PMCID: PMC7181798 DOI: 10.1038/s41467-020-15891-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 03/30/2020] [Indexed: 11/17/2022] Open
Abstract
There is the notion that infection with a virulent intestinal pathogen induces generally stronger mucosal adaptive immunity than the exposure to an avirulent strain. Whether the associated mucosal inflammation is important or redundant for effective induction of immunity is, however, still unclear. Here we use a model of auxotrophic Salmonella infection in germ-free mice to show that live bacterial virulence factor-driven immunogenicity can be uncoupled from inflammatory pathogenicity. Although live auxotrophic Salmonella no longer causes inflammation, its mucosal virulence factors remain the main drivers of protective mucosal immunity; virulence factor-deficient, like killed, bacteria show reduced efficacy. Assessing the involvement of innate pathogen sensing mechanisms, we show MYD88/TRIF, Caspase-1/Caspase-11 inflammasome, and NOD1/NOD2 nodosome signaling to be individually redundant. In colonized animals we show that microbiota metabolite cross-feeding may recover intestinal luminal colonization but not pathogenicity. Consequent immunoglobulin A immunity and microbial niche competition synergistically protect against Salmonella wild-type infection.
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Affiliation(s)
- Simona P Pfister
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Graduate School GCB, University of Bern, Bern, Switzerland
| | - Olivier P Schären
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Graduate School GCB, University of Bern, Bern, Switzerland
| | - Luca Beldi
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Andrea Printz
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Matheus D Notter
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Graduate School GCB, University of Bern, Bern, Switzerland
| | - Mohana Mukherjee
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Graduate School GCB, University of Bern, Bern, Switzerland
| | - Hai Li
- Maurice Müller Laboratories (DBMR), Universitätsklinik für Viszerale Chirurgie und Medizin (UVCM) Inselspital, Bern, Switzerland
| | - Julien P Limenitakis
- Maurice Müller Laboratories (DBMR), Universitätsklinik für Viszerale Chirurgie und Medizin (UVCM) Inselspital, Bern, Switzerland
| | - Joel P Werren
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Graduate School GCB, University of Bern, Bern, Switzerland
| | - Disha Tandon
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
- Graduate School GCB, University of Bern, Bern, Switzerland
| | - Miguelangel Cuenca
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Stefanie Hagemann
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Stephanie S Uster
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Miguel A Terrazos
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Mercedes Gomez de Agüero
- Maurice Müller Laboratories (DBMR), Universitätsklinik für Viszerale Chirurgie und Medizin (UVCM) Inselspital, Bern, Switzerland
| | - Christian M Schürch
- Institute of Pathology, University of Bern, Bern, Switzerland
- Institute of Pathology and Neuropathology and Comprehensive Cancer Center, University Hospital Tübingen, Tübingen, Germany
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Fernanda M Coelho
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Roy Curtiss
- Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Emma Slack
- Institute for Food, Nutrition and Health, D-HEST, ETH Zürich, Switzerland
| | - Maria L Balmer
- Department of Biomedicine, Immunobiology, University of Basel, Basel, Switzerland
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11
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Type three secretion system in Salmonella Typhimurium: the key to infection. Genes Genomics 2020; 42:495-506. [PMID: 32112371 DOI: 10.1007/s13258-020-00918-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 02/12/2020] [Indexed: 11/27/2022]
Abstract
BACKGROUND Type Three Secretion Systems (T3SS) are nanomachine complexes, which display the ability to inject effector proteins directly into host cells. This skill allows for gram-negative bacteria to modulate several host cell responses, such as cytoskeleton rearrangement, signal transduction, and cytokine production, which in turn increase the pathogenicity of these bacteria. The Salmonella enterica subsp. enterica serovar Typhimurium (ST) T3SS has been the most characterized so far. Among gram-negative bacterium, ST is one of enterica groups predicted to have two T3SSs activated during different phases of infection. OBJECTIVE To comprise current information about ST T3SS structure and function as well as an overview of its assembly and hierarchical regulation. METHODS With a brief and straightforward reading, this review summarized aspects of both ST T3SS, such as its structure and function. That was possible due to the development of novel techniques, such as X-ray crystallography, cryoelectron microscopy, and nano-gold labelling, which also elucidated the mechanisms behind T3SS assembly and regulation, which was addressed in this review. CONCLUSION This paper provided fundamental overview of ST T3SS assembly and regulation, besides summarized the structure and function of this complex. Due to T3SS relevance in ST pathogenicity, this complex could become a potential target in therapeutic studies as this nanomachine modulates the infection process.
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12
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High-resolution view of the type III secretion export apparatus in situ reveals membrane remodeling and a secretion pathway. Proc Natl Acad Sci U S A 2019; 116:24786-24795. [PMID: 31744874 DOI: 10.1073/pnas.1916331116] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Type III protein secretion systems are essential virulence factors for many important pathogenic bacteria. The entire protein secretion machine is composed of several substructures that organize into a holostructure or injectisome. The core component of the injectisome is the needle complex, which houses the export apparatus that serves as a gate for the passage of the secreted proteins through the bacterial inner membrane. Here, we describe a high-resolution structure of the export apparatus of the Salmonella type III secretion system in association with the needle complex and the underlying bacterial membrane, both in isolation and in situ. We show the precise location of the core export apparatus components within the injectisome and bacterial envelope and demonstrate that their deployment results in major membrane remodeling and thinning, which may be central for the protein translocation process. We also show that InvA, a critical export apparatus component, forms a multiring cytoplasmic conduit that provides a pathway for the type III secretion substrates to reach the entrance of the export gate. Combined with structure-guided mutagenesis, our studies provide major insight into potential mechanisms of protein translocation and injectisome assembly.
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13
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Singh N, Wagner S. Investigating the assembly of the bacterial type III secretion system injectisome by in vivo photocrosslinking. Int J Med Microbiol 2019; 309:151331. [DOI: 10.1016/j.ijmm.2019.151331] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/09/2019] [Accepted: 07/12/2019] [Indexed: 12/11/2022] Open
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14
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Lou L, Zhang P, Piao R, Wang Y. Salmonella Pathogenicity Island 1 (SPI-1) and Its Complex Regulatory Network. Front Cell Infect Microbiol 2019; 9:270. [PMID: 31428589 PMCID: PMC6689963 DOI: 10.3389/fcimb.2019.00270] [Citation(s) in RCA: 169] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/12/2019] [Indexed: 11/30/2022] Open
Abstract
Salmonella species can infect a diverse range of birds, reptiles, and mammals, including humans. The type III protein secretion system (T3SS) encoded by Salmonella pathogenicity island 1 (SPI-1) delivers effector proteins required for intestinal invasion and the production of enteritis. The T3SS is regarded as the most important virulence factor of Salmonella. SPI-1 encodes transcription factors that regulate the expression of some virulence factors of Salmonella, while other transcription factors encoded outside SPI-1 participate in the expression of SPI-1-encoded genes. SPI-1 genes are responsible for the invasion of host cells, regulation of the host immune response, e.g., the host inflammatory response, immune cell recruitment and apoptosis, and biofilm formation. The regulatory network of SPI-1 is very complex and crucial. Here, we review the function, effectors, and regulation of SPI-1 genes and their contribution to the pathogenicity of Salmonella.
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Affiliation(s)
- Lixin Lou
- Department of Infectious Diseases, First Hospital of Jilin University, Changchun, China
| | - Peng Zhang
- Department of Infectious Diseases, First Hospital of Jilin University, Changchun, China.,Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Rongli Piao
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Gastroenterology, First Hospital of Jilin University, Changchun, China
| | - Yang Wang
- Department of Infectious Diseases, First Hospital of Jilin University, Changchun, China.,Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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15
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Guo EZ, Desrosiers DC, Zalesak J, Tolchard J, Berbon M, Habenstein B, Marlovits T, Loquet A, Galán JE. A polymorphic helix of a Salmonella needle protein relays signals defining distinct steps in type III secretion. PLoS Biol 2019; 17:e3000351. [PMID: 31260457 PMCID: PMC6625726 DOI: 10.1371/journal.pbio.3000351] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 07/12/2019] [Accepted: 06/18/2019] [Indexed: 12/22/2022] Open
Abstract
Type III protein-secretion machines are essential for the interactions of many pathogenic or symbiotic bacterial species with their respective eukaryotic hosts. The core component of these machines is the injectisome, a multiprotein complex that mediates the selection of substrates, their passage through the bacterial envelope, and ultimately their delivery into eukaryotic target cells. The injectisome is composed of a large cytoplasmic complex or sorting platform, a multiring base embedded in the bacterial envelope, and a needle-like filament that protrudes several nanometers from the bacterial surface and is capped at its distal end by the tip complex. A characteristic feature of these machines is that their activity is stimulated by contact with target host cells. The sensing of target cells, thought to be mediated by the distal tip of the needle filament, generates an activating signal that must be transduced to the secretion machine by the needle filament. Here, through a multidisciplinary approach, including solid-state NMR (SSNMR) and cryo electron microscopy (cryo-EM) analyses, we have identified critical residues of the needle filament protein of a Salmonella Typhimurium type III secretion system that are involved in the regulation of the activity of the secretion machine. We found that mutations in the needle filament protein result in various specific phenotypes associated with different steps in the type III secretion process. More specifically, these studies reveal an important role for a polymorphic helix of the needle filament protein and the residues that line the lumen of its central channel in the control of type III secretion.
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Affiliation(s)
- Emily Z. Guo
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Daniel C. Desrosiers
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jan Zalesak
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
| | - James Tolchard
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Mélanie Berbon
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Birgit Habenstein
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Thomas Marlovits
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE) and German Electron Synchrotron Centre (DESY), Hamburg, Germany
| | - Antoine Loquet
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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16
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Torres‐Vargas CE, Kronenberger T, Roos N, Dietsche T, Poso A, Wagner S. The inner rod of virulence‐associated type III secretion systems constitutes a needle adapter of one helical turn that is deeply integrated into the system's export apparatus. Mol Microbiol 2019; 112:918-931. [DOI: 10.1111/mmi.14327] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2019] [Indexed: 12/22/2022]
Affiliation(s)
- Claudia E. Torres‐Vargas
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Elfriede‐Aulhorn‐Str. 6Tübingen 72076Germany
| | - Thales Kronenberger
- Department of Internal Medicine VIII University Hospital Tübingen Otfried‐Müller‐Str. 14Tübingen 72076Germany
- School of Pharmacy University of Eastern Finland P.O. Box 1627Kuopio 70211Finland
| | - Nora Roos
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Elfriede‐Aulhorn‐Str. 6Tübingen 72076Germany
| | - Tobias Dietsche
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Elfriede‐Aulhorn‐Str. 6Tübingen 72076Germany
| | - Antti Poso
- Department of Internal Medicine VIII University Hospital Tübingen Otfried‐Müller‐Str. 14Tübingen 72076Germany
- School of Pharmacy University of Eastern Finland P.O. Box 1627Kuopio 70211Finland
| | - Samuel Wagner
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT) University of Tübingen Elfriede‐Aulhorn‐Str. 6Tübingen 72076Germany
- Partner‐Site Tübingen German Center for Infection Research (DZIF) Elfriede‐Aulhorn‐Str. 6Tübingen 72076Germany
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17
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Takaya A, Takeda H, Tashiro S, Kawashima H, Yamamoto T. Chaperone-mediated secretion switching from early to middle substrates in the type III secretion system encoded by Salmonella pathogenicity island 2. J Biol Chem 2019; 294:3783-3793. [PMID: 30651351 DOI: 10.1074/jbc.ra118.005072] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 01/07/2019] [Indexed: 11/06/2022] Open
Abstract
The bacterial type III secretion system (T3SS) delivers virulence proteins, called effectors, into eukaryotic cells. T3SS comprises a transmembrane secretion apparatus and a complex network of specialized chaperones that target protein substrates to this secretion apparatus. However, the regulation of secretion switching from early (needle and inner rod) to middle (tip/filament and translocators) substrates is incompletely understood. Here, we investigated chaperone-mediated secretion switching from early to middle substrates in the T3SS encoded by Salmonella pathogenicity island 2 (SPI2), essential for systemic infection. Our findings revealed that the protein encoded by ssaH regulates the secretion of an inner rod and early substrate, SsaI. Structural modeling revealed that SsaH is structurally similar to class III chaperones, known to associate with proteins in various pathogenic bacteria. The SPI2 protein SsaE was identified as a class V chaperone homolog and partner of SsaH. A pulldown analysis disclosed that SsaH and SsaE form a heterodimer, which interacted with another early substrate, the needle protein SsaG. Moreover, SsaE also helped stabilize SsaH and a middle substrate, SseB. We also found that SsaE regulates cellular SsaH levels to translocate the early substrates SsaG and SsaI and then promotes the translocation of SseB by stabilizing it. In summary, our results indicate that the class III chaperone SsaH facilitates SsaI secretion, and a heterodimer of SsaH and the type V chaperone SsaE then switches secretion to SsaG. This is the first report of a chaperone system that regulates both early and middle substrates during substrate switching for T3SS assembly.
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Affiliation(s)
- Akiko Takaya
- From the Laboratory of Microbiology and Immunology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan and
| | - Hikari Takeda
- From the Laboratory of Microbiology and Immunology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan and
| | - Shogo Tashiro
- From the Laboratory of Microbiology and Immunology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan and
| | - Hiroto Kawashima
- From the Laboratory of Microbiology and Immunology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan and
| | - Tomoko Yamamoto
- Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
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18
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Diepold A. Assembly and Post-assembly Turnover and Dynamics in the Type III Secretion System. Curr Top Microbiol Immunol 2019; 427:35-66. [PMID: 31218503 DOI: 10.1007/82_2019_164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The type III secretion system (T3SS) is one of the largest transmembrane complexes in bacteria, comprising several intricately linked and embedded substructures. The assembly of this nanomachine is a hierarchical process which is regulated and controlled by internal and external cues at several critical points. Recently, it has become obvious that the assembly of the T3SS is not a unidirectional and deterministic process, but that parts of the T3SS constantly exchange or rearrange. This article aims to give an overview on the assembly and post-assembly dynamics of the T3SS, with a focus on emerging general concepts and adaptations of the general assembly pathway.
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Affiliation(s)
- Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, 35043, Marburg, Germany.
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19
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Habenstein B, El Mammeri N, Tolchard J, Lamon G, Tawani A, Berbon M, Loquet A. Structures of Type III Secretion System Needle Filaments. Curr Top Microbiol Immunol 2019; 427:109-131. [PMID: 31974760 DOI: 10.1007/82_2019_192] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Among the Gram-negative bacterial secretion systems, type III secretion systems (T3SS) possess a unique extracellular molecular apparatus called the needle. This macromolecular protein assembly is a nanometre-size filament formed by the helical arrangement of hundreds of copies of a single, small protein, which is highly conserved between T3SSs from animal to plant bacterial pathogens. The needle filament forms a hollow tube with a channel ~20 Å in diameter that serves as a conduit for proteins secreted into the targeted host cell. In the past ten years, technical breakthroughs in biophysical techniques such as cryo-electron microscopy (cryo-EM) and solid-state NMR (SSNMR) spectroscopy have uncovered atomic resolution details about the T3SS needle assembly. Several high-resolution structures of Salmonella typhimurium and Shigella flexneri T3SS needles have been reported demonstrating a common structural fold. These structural models have been used to explain the active role of the needle in transmitting the host-cell contact signal from the tip to the base of the T3SS through conformational changes as well as during the injection of effector proteins. In this chapter, we summarize the current knowledge about the structure and the role of the T3SS needle during T3SS assembly and effector secretion.
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Affiliation(s)
- Birgit Habenstein
- University of Bordeaux, CNRS, UMR 5248, European Institute of Chemistry and Biology, 2 rue Robert Escarpit, Pessac, 33607, France.
| | - Nadia El Mammeri
- University of Bordeaux, CNRS, UMR 5248, European Institute of Chemistry and Biology, 2 rue Robert Escarpit, Pessac, 33607, France
| | - James Tolchard
- University of Bordeaux, CNRS, UMR 5248, European Institute of Chemistry and Biology, 2 rue Robert Escarpit, Pessac, 33607, France
| | - Gaëlle Lamon
- University of Bordeaux, CNRS, UMR 5248, European Institute of Chemistry and Biology, 2 rue Robert Escarpit, Pessac, 33607, France
| | - Arpita Tawani
- University of Bordeaux, CNRS, UMR 5248, European Institute of Chemistry and Biology, 2 rue Robert Escarpit, Pessac, 33607, France
| | - Mélanie Berbon
- University of Bordeaux, CNRS, UMR 5248, European Institute of Chemistry and Biology, 2 rue Robert Escarpit, Pessac, 33607, France
| | - Antoine Loquet
- University of Bordeaux, CNRS, UMR 5248, European Institute of Chemistry and Biology, 2 rue Robert Escarpit, Pessac, 33607, France.
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20
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Wagner S, Grin I, Malmsheimer S, Singh N, Torres-Vargas CE, Westerhausen S. Bacterial type III secretion systems: a complex device for the delivery of bacterial effector proteins into eukaryotic host cells. FEMS Microbiol Lett 2018; 365:5068689. [PMID: 30107569 PMCID: PMC6140923 DOI: 10.1093/femsle/fny201] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 08/08/2018] [Indexed: 12/21/2022] Open
Abstract
Virulence-associated type III secretion systems (T3SS) serve the injection of bacterial effector proteins into eukaryotic host cells. They are able to secrete a great diversity of substrate proteins in order to modulate host cell function, and have evolved to sense host cell contact and to inject their substrates through a translocon pore in the host cell membrane. T3SS substrates contain an N-terminal signal sequence and often a chaperone-binding domain for cognate T3SS chaperones. These signals guide the substrates to the machine where substrates are unfolded and handed over to the secretion channel formed by the transmembrane domains of the export apparatus components and by the needle filament. Secretion itself is driven by the proton motive force across the bacterial inner membrane. The needle filament measures 20-150 nm in length and is crowned by a needle tip that mediates host-cell sensing. Secretion through T3SS is a highly regulated process with early, intermediate and late substrates. A strict secretion hierarchy is required to build an injectisome capable of reaching, sensing and penetrating the host cell membrane, before host cell-acting effector proteins are deployed. Here, we review the recent progress on elucidating the assembly, structure and function of T3SS injectisomes.
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Affiliation(s)
- Samuel Wagner
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
- German Center for Infection Research (DZIF), partner-site Tübingen, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
| | - Iwan Grin
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
| | - Silke Malmsheimer
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
| | - Nidhi Singh
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
| | - Claudia E Torres-Vargas
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
| | - Sibel Westerhausen
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
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21
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Kato J, Dey S, Soto JE, Butan C, Wilkinson MC, De Guzman RN, Galan JE. A protein secreted by the Salmonella type III secretion system controls needle filament assembly. eLife 2018; 7:e35886. [PMID: 30015613 PMCID: PMC6066329 DOI: 10.7554/elife.35886] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 07/16/2018] [Indexed: 12/14/2022] Open
Abstract
Type III protein secretion systems (T3SS) are encoded by several pathogenic or symbiotic bacteria. The central component of this nanomachine is the needle complex. Here we show in a Salmonella Typhimurium T3SS that assembly of the needle filament of this structure requires OrgC, a protein encoded within the T3SS gene cluster. Absence of OrgC results in significantly reduced number of needle substructures but does not affect needle length. We show that OrgC is secreted by the T3SS and that exogenous addition of OrgC can complement a ∆orgC mutation. We also show that OrgC interacts with the needle filament subunit PrgI and accelerates its polymerization into filaments in vitro. The structure of OrgC shows a novel fold with a shared topology with a domain from flagellar capping proteins. These findings identify a novel component of T3SS and provide new insight into the assembly of the type III secretion machine.
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Affiliation(s)
- Junya Kato
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Supratim Dey
- Department of Molecular BiosciencesUniversity of KansasLawrenceUnited States
| | - Jose E Soto
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Carmen Butan
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Mason C Wilkinson
- Department of Molecular BiosciencesUniversity of KansasLawrenceUnited States
| | - Roberto N De Guzman
- Department of Molecular BiosciencesUniversity of KansasLawrenceUnited States
| | - Jorge E Galan
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
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22
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dos Santos AMP, Ferrari RG, Conte-Junior CA. Virulence Factors in Salmonella Typhimurium: The Sagacity of a Bacterium. Curr Microbiol 2018; 76:762-773. [DOI: 10.1007/s00284-018-1510-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 05/16/2018] [Indexed: 12/20/2022]
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23
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Gurung JM, Amer AAA, Francis MK, Costa TRD, Chen S, Zavialov AV, Francis MS. Heterologous Complementation Studies With the YscX and YscY Protein Families Reveals a Specificity for Yersinia pseudotuberculosis Type III Secretion. Front Cell Infect Microbiol 2018; 8:80. [PMID: 29616194 PMCID: PMC5864894 DOI: 10.3389/fcimb.2018.00080] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Accepted: 02/28/2018] [Indexed: 12/29/2022] Open
Abstract
Type III secretion systems harbored by several Gram-negative bacteria are often used to deliver host-modulating effectors into infected eukaryotic cells. About 20 core proteins are needed for assembly of a secretion apparatus. Several of these proteins are genetically and functionally conserved in type III secretion systems of bacteria associated with invertebrate or vertebrate hosts. In the Ysc family of type III secretion systems are two poorly characterized protein families, the YscX family and the YscY family. In the plasmid-encoded Ysc-Yop type III secretion system of human pathogenic Yersinia species, YscX is a secreted substrate while YscY is its non-secreted cognate chaperone. Critically, neither an yscX nor yscY null mutant of Yersinia is capable of type III secretion. In this study, we show that the genetic equivalents of these proteins produced as components of other type III secretion systems of Pseudomonas aeruginosa (PscX and PscY), Aeromonas species (AscX and AscY), Vibrio species (VscX and VscY), and Photorhabdus luminescens (SctX and SctY) all possess an ability to interact with its native cognate partner and also establish cross-reciprocal binding to non-cognate partners as judged by a yeast two-hybrid assay. Moreover, a yeast three-hybrid assay also revealed that these heterodimeric complexes could maintain an interaction with YscV family members, a core membrane component of all type III secretion systems. Despite maintaining these molecular interactions, only expression of the native yscX in the near full-length yscX deletion and native yscY in the near full-length yscY deletion were able to complement for their general substrate secretion defects. Hence, YscX and YscY must have co-evolved to confer an important function specifically critical for Yersinia type III secretion.
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Affiliation(s)
- Jyoti M Gurung
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Ayad A A Amer
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Monika K Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Tiago R D Costa
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences Wuhan, Wuhan, China
| | | | - Matthew S Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
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The role of EscD in supporting EscC polymerization in the type III secretion system of enteropathogenic Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:384-395. [PMID: 28988128 DOI: 10.1016/j.bbamem.2017.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 10/01/2017] [Accepted: 10/02/2017] [Indexed: 11/23/2022]
Abstract
The type III secretion system (T3SS) is a multi-protein complex that plays a central role in the virulence of many Gram-negative bacterial pathogens. In enteropathogenic Escherichia coli, a prevalent cause of diarrheal diseases, the needle complex base of the T3SS is formed by multi-rings: two concentric inner-membrane rings made by the two oligomerizing proteins (EscD and EscJ), and an outer ring made of a single oligomerizing protein (EscC). Although the oligomerization activity of these proteins is critical for their function and can, therefore, affect the virulence of the pathogen, the mechanisms underlying the oligomerization of these proteins have yet to be identified. In this study, we report that the proteins forming the inner-membrane T3SS rings, EscJ and EscD proteins, are crucial for the oligomerization of EscC. Moreover, we elucidate the oligomerization process of EscD and determine the contribution of individual regions of the protein to its self-oligomerization activity. We show that the oligomerization motif of EscD is located at its N-terminal portion and that its transmembrane domain can self-oligomerize, thus contributing to the self-oligomerization of the full-length EscD.
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InvS Coordinates Expression of PrgH and FimZ and Is Required for Invasion of Epithelial Cells by Salmonella enterica serovar Typhimurium. J Bacteriol 2017; 199:JB.00824-16. [PMID: 28439039 DOI: 10.1128/jb.00824-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 04/20/2017] [Indexed: 11/20/2022] Open
Abstract
Deep sequencing has revolutionized our understanding of the bacterial RNA world and has facilitated the identification of 280 small RNAs (sRNAs) in Salmonella Despite the suspicions that sRNAs may play important roles in Salmonella pathogenesis, the functions of most sRNAs remain unknown. To advance our understanding of RNA biology in Salmonella virulence, we searched for sRNAs required for bacterial invasion into nonphagocytic cells. After screening 75 sRNAs, we discovered that the ablation of InvS caused a significant decrease of Salmonella invasion into epithelial cells. A proteomic analysis showed that InvS modulated the levels of several type III secreted Salmonella proteins. The level of PrgH, a type III secretion apparatus protein, was significantly lower in the absence of InvS, consistent with the known roles of PrgH in effector secretion and bacterial invasion. We discovered that InvS modulates fimZ expression and hence flagellar gene expression and motility. We propose that InvS coordinates the increase of PrgH and decrease in FimZ that promote efficient Salmonella invasion into nonphagocytic cells.IMPORTANCE Salmonellosis continues to be the most common foodborne infection reported by the CDC in the United States. Central to Salmonella pathogenesis is the ability to invade nonphagocytic cells and to replicate inside host cells. Invasion genes are known to be regulated by protein transcriptional networks, but little is known about the role played by small RNAs (sRNAs) in this process. We have identified a novel sRNA, InvS, that is involved in Salmonella invasion. Our result will likely provide an opportunity to better understand the fundamental question of how Salmonella regulates invasion gene expression and may inform strategies for therapeutic intervention.
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Control of type III protein secretion using a minimal genetic system. Nat Commun 2017; 8:14737. [PMID: 28485369 PMCID: PMC5436071 DOI: 10.1038/ncomms14737] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/27/2017] [Indexed: 01/12/2023] Open
Abstract
Gram-negative bacteria secrete proteins using a type III secretion system (T3SS), which functions as a needle-like molecular machine. The many proteins involved in T3SS construction are tightly regulated due to its role in pathogenesis and motility. Here, starting with the 35 kb Salmonella pathogenicity island 1 (SPI-1), we eliminated internal regulation and simplified the genetics by removing or recoding genes, scrambling gene order and replacing all non-coding DNA with synthetic genetic parts. This process results in a 16 kb cluster that shares no sequence identity, regulation or organizational principles with SPI-1. Building this simplified system led to the discovery of essential roles for an internal start site (SpaO) and small RNA (InvR). Further, it can be controlled using synthetic regulatory circuits, including under SPI-1 repressing conditions. This work reveals an incredible post-transcriptional robustness in T3SS assembly and aids its control as a tool in biotechnology.
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Kovac J, Cummings KJ, Rodriguez-Rivera LD, Carroll LM, Thachil A, Wiedmann M. Temporal Genomic Phylogeny Reconstruction Indicates a Geospatial Transmission Path of Salmonella Cerro in the United States and a Clade-Specific Loss of Hydrogen Sulfide Production. Front Microbiol 2017; 8:737. [PMID: 28507536 PMCID: PMC5410586 DOI: 10.3389/fmicb.2017.00737] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 04/10/2017] [Indexed: 12/21/2022] Open
Abstract
Salmonella Cerro has become one of the most prevalent Salmonella serotypes isolated from dairy cattle in several U.S. states, including New York where it represented 36% of all Salmonella isolates of bovine origin in 2015. This serotype is commonly isolated from dairy cattle with clinical signs of salmonellosis, including diarrhea and fever, although it has also been identified in herds without evidence of clinical disease or decreased production. To better understand the transmission patterns and drivers of its geographic spread, we have studied the genomic similarity and microevolution of S. Cerro isolates from the northeast U.S. and Texas. Eighty-three out of 86 isolates were confirmed as multilocus sequence type 367. We identified core genome SNPs in 57 upstate New York (NY), 2 Pennsylvania (PA), and 27 Texas S. Cerro isolates from dairy cattle, farm environments, raw milk, and one human clinical case and used them to construct a tip-dated phylogeny. S. Cerro isolates clustered in three distinct clades, including (i) clade I (n = 3; 2013) comprising isolates from northwest Texas (NTX), (ii) clade II (n = 14; 2009–2011, 2014) comprising isolates from NY, and (iii) clade III comprising isolates from NY, PA, and central Texas (CTX) in subclade IIIa (n = 45; 2008–2014), and only CTX isolates in subclade IIIb (n = 24; 2013). Temporal phylogenetic analysis estimated the divergence of these three clades from the most recent common ancestor in approximately 1980. The CTX clade IIIb was estimated to have evolved and diverged from the NY ancestor around 2004. Furthermore, gradual temporal loss of genes encoding a D-alanine transporter, involved in virulence, was observed. These genes were present in the isolates endemic to NTX clade I and were gradually lost in clades II and III. The virulence gene orgA, which is part of the Salmonella Pathogenicity Island 1, was lost in a subgroup of Texas isolates in clades I and IIIb. All S. Cerro isolates had an additional cytosine inserted in a cytosine-rich region of the virulence gene sopA, resulting in premature termination of translation likely responsible for loss of pathogenic capacity in humans. A group of closely related NY isolates was characterized by the loss of hydrogen sulfide production due to the truncation or complete loss of phsA. Our data suggest the ability of Salmonella to rapidly diverge and adapt to specific niches (e.g., bovine niche), and to modify virulence-related characteristics such as the ability to utilize tetrathionate as an alternative electron acceptor, which is commonly used to detect Salmonella. Overall, our results show that clinical outcome data and genetic data for S. Cerro isolates, such as truncations in virulence genes leading to novel pheno- and pathotypes, should be correlated to allow for accurate risk assessment.
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Affiliation(s)
- Jasna Kovac
- Department of Food Science, Cornell University, IthacaNY, USA
| | - Kevin J Cummings
- Department of Veterinary Integrative Biosciences, Texas A&M University, College StationTX, USA
| | | | - Laura M Carroll
- Department of Food Science, Cornell University, IthacaNY, USA
| | - Anil Thachil
- Department of Population Medicine and Diagnostic Sciences, Cornell University, IthacaNY, USA
| | - Martin Wiedmann
- Department of Food Science, Cornell University, IthacaNY, USA
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Functional Characterization of EscK (Orf4), a Sorting Platform Component of the Enteropathogenic Escherichia coli Injectisome. J Bacteriol 2016; 199:JB.00538-16. [PMID: 27795324 DOI: 10.1128/jb.00538-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/03/2016] [Indexed: 02/07/2023] Open
Abstract
The type III secretion system (T3SS) is a supramolecular machine used by many bacterial pathogens to translocate effector proteins directly into the eukaryotic host cell cytoplasm. Enteropathogenic Escherichia coli (EPEC) is an important cause of infantile diarrheal disease in underdeveloped countries. EPEC virulence relies on a T3SS encoded within a chromosomal pathogenicity island known as the locus of enterocyte effacement (LEE). In this work, we pursued the functional characterization of the LEE-encoded protein EscK (previously known as Orf4). We provide evidence indicating that EscK is crucial for efficient T3S and belongs to the SctK (OrgA/YscK/MxiK) protein family, whose members have been implicated in the formation of a sorting platform for secretion of T3S substrates. Bacterial fractionation studies showed that EscK localizes to the inner membrane independently of the presence of any other T3SS component. Combining yeast two-hybrid screening and pulldown assays, we identified an interaction between EscK and the C-ring/sorting platform component EscQ. Site-directed mutagenesis of conserved residues revealed amino acids that are critical for EscK function and for its interaction with EscQ. In addition, we found that T3S substrate overproduction is capable of compensating for the absence of EscK. Overall, our data suggest that EscK is a structural component of the EPEC T3SS sorting platform, playing a central role in the recruitment of T3S substrates for boosting the efficiency of the protein translocation process. IMPORTANCE The type III secretion system (T3SS) is an essential virulence determinant for enteropathogenic Escherichia coli (EPEC) colonization of intestinal epithelial cells. Multiple EPEC effector proteins are injected via the T3SS into enterocyte cells, leading to diarrheal disease. The T3SS is encoded within a genomic pathogenicity island termed the locus of enterocyte effacement (LEE). Here we unravel the function of EscK, a previously uncharacterized LEE-encoded protein. We show that EscK is central for T3SS biogenesis and function. EscK forms a protein complex with EscQ, the main component of the cytoplasmic sorting platform, serving as a docking site for T3S substrates. Our results provide a comprehensive functional analysis of an understudied component of T3SSs.
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Burgess JL, Burgess RA, Morales Y, Bouvang JM, Johnson SJ, Dickenson NE. Structural and Biochemical Characterization of Spa47 Provides Mechanistic Insight into Type III Secretion System ATPase Activation and Shigella Virulence Regulation. J Biol Chem 2016; 291:25837-25852. [PMID: 27770024 DOI: 10.1074/jbc.m116.755256] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 10/21/2016] [Indexed: 11/06/2022] Open
Abstract
Like many Gram-negative pathogens, Shigella rely on a complex type III secretion system (T3SS) to inject effector proteins into host cells, take over host functions, and ultimately establish infection. Despite these critical roles, the energetics and regulatory mechanisms controlling the T3SS and pathogen virulence remain largely unclear. In this study, we present a series of high resolution crystal structures of Spa47 and use the structures to model an activated Spa47 oligomer, finding that ATP hydrolysis may be supported by specific side chain contributions from adjacent protomers within the complex. Follow-up mutagenesis experiments targeting the predicted active site residues validate the oligomeric model and determined that each of the tested residues are essential for Spa47 ATPase activity, although they are not directly responsible for stable oligomer formation. Although N-terminal domain truncation was necessary for crystal formation, it resulted in strictly monomeric Spa47 that is unable to hydrolyze ATP, despite maintaining the canonical ATPase core structure and active site residues. Coupled with studies of ATPase inactive full-length Spa47 point mutants, we find that Spa47 oligomerization and ATP hydrolysis are needed for complete T3SS apparatus formation, a proper translocator secretion profile, and Shigella virulence. This work represents the first structure-function characterization of Spa47, uniquely complementing the multitude of included Shigella T3SS phenotype assays and providing a more complete understanding of T3SS ATPase-mediated pathogen virulence. Additionally, these findings provide a strong platform for follow-up studies evaluating regulation of Spa47 oligomerization in vivo as a much needed means of treating and perhaps preventing shigellosis.
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Affiliation(s)
- Jamie L Burgess
- From the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - R Alan Burgess
- From the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Yalemi Morales
- From the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Jenna M Bouvang
- From the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Sean J Johnson
- From the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Nicholas E Dickenson
- From the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
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Gaytán MO, Martínez-Santos VI, Soto E, González-Pedrajo B. Type Three Secretion System in Attaching and Effacing Pathogens. Front Cell Infect Microbiol 2016; 6:129. [PMID: 27818950 PMCID: PMC5073101 DOI: 10.3389/fcimb.2016.00129] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/27/2016] [Indexed: 02/06/2023] Open
Abstract
Enteropathogenic Escherichia coli and enterohemorrhagic E. coli are diarrheagenic bacterial human pathogens that cause severe gastroenteritis. These enteric pathotypes, together with the mouse pathogen Citrobacter rodentium, belong to the family of attaching and effacing pathogens that form a distinctive histological lesion in the intestinal epithelium. The virulence of these bacteria depends on a type III secretion system (T3SS), which mediates the translocation of effector proteins from the bacterial cytosol into the infected cells. The core architecture of the T3SS consists of a multi-ring basal body embedded in the bacterial membranes, a periplasmic inner rod, a transmembrane export apparatus in the inner membrane, and cytosolic components including an ATPase complex and the C-ring. In addition, two distinct hollow appendages are assembled on the extracellular face of the basal body creating a channel for protein secretion: an approximately 23 nm needle, and a filament that extends up to 600 nm. This filamentous structure allows these pathogens to get through the host cells mucus barrier. Upon contact with the target cell, a translocation pore is assembled in the host membrane through which the effector proteins are injected. Assembly of the T3SS is strictly regulated to ensure proper timing of substrate secretion. The different type III substrates coexist in the bacterial cytoplasm, and their hierarchical secretion is determined by specialized chaperones in coordination with two molecular switches and the so-called sorting platform. In this review, we present recent advances in the understanding of the T3SS in attaching and effacing pathogens.
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Affiliation(s)
- Meztlli O Gaytán
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Verónica I Martínez-Santos
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Eduardo Soto
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Bertha González-Pedrajo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
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New Insights into the Formation of Viable but Nonculturable Escherichia coli O157:H7 Induced by High-Pressure CO2. mBio 2016; 7:mBio.00961-16. [PMID: 27578754 PMCID: PMC4999544 DOI: 10.1128/mbio.00961-16] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The formation of viable but nonculturable (VBNC) Escherichia coli O157:H7 induced by high-pressure CO2 (HPCD) was investigated using RNA sequencing (RNA-Seq) transcriptomics and isobaric tag for relative and absolute quantitation (iTRAQ) proteomic methods. The analyses revealed that 97 genes and 56 proteins were significantly changed upon VBNC state entry. Genes and proteins related to membrane transport, central metabolisms, DNA replication, and cell division were mainly downregulated in the VBNC cells. This caused low metabolic activity concurrently with a division arrest in cells, which may be related to VBNC state formation. Cell division repression and outer membrane overexpression were confirmed to be involved in VBNC state formation by homologous expression of z2046 coding for transcriptional repressor and ompF encoding outer membrane protein F. Upon VBNC state entry, pyruvate catabolism in the cells shifted from the tricarboxylic acid (TCA) cycle toward the fermentative route; this led to a low level of ATP. Combating the low energy supply, ATP production in the VBNC cells was compensated by the degradation of l-serine and l-threonine, the increased AMP generation, and the enhanced electron transfer. Furthermore, tolerance of the cells with respect to HPCD-induced acid, oxidation, and high CO2 stresses was enhanced by promoting the production of ammonia and NADPH and by reducing CO2 production during VBNC state formation. Most genes and proteins related to pathogenicity were downregulated in the VBNC cells. This would decrease the cell pathogenicity, which was confirmed by adhesion assays. In conclusion, the decreased metabolic activity, repressed cell division, and enhanced survival ability in E. coli O157:H7 might cause HPCD-induced VBNC state formation. Escherichia coli O157:H7 has been implicated in large foodborne outbreaks worldwide. It has been reported that the presence of as few as 10 cells in food could cause illness. However, the presence of only 0.73 to 1.5 culturable E. coli O157:H7 cells in salted salmon roe caused infection in Japan. Investigators found that E. coli O157:H7 in the viable but nonculturable (VBNC) state was the source of the outbreak. So far, formation mechanisms of VBNC state are not well known. In a previous study, we demonstrated that high-pressure CO2 (HPCD) could induce the transition of E. coli O157:H7 into the VBNC state. In this study, we used RNA-Seq transcriptomic analysis combined with the iTRAQ proteomic method to investigate the formation of VBNC E. coli O157:H7 induced by HPCD treatment. Finally, we proposed a putative formation mechanism of the VBNC cells induced by HPCD, which may provide a theoretical foundation for controlling the VBNC state entry induced by HPCD treatment.
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Tsou LK, Lara-Tejero M, RoseFigura J, Zhang ZJ, Wang YC, Yount JS, Lefebre M, Dossa PD, Kato J, Guan F, Lam W, Cheng YC, Galán JE, Hang HC. Antibacterial Flavonoids from Medicinal Plants Covalently Inactivate Type III Protein Secretion Substrates. J Am Chem Soc 2016; 138:2209-18. [PMID: 26847396 DOI: 10.1021/jacs.5b11575] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Traditional Chinese Medicines (TCMs) have been historically used to treat bacterial infections. However, the molecules responsible for these anti-infective properties and their potential mechanisms of action have remained elusive. Using a high-throughput assay for type III protein secretion in Salmonella enterica serovar Typhimurium, we discovered that several TCMs can attenuate this key virulence pathway without affecting bacterial growth. Among the active TCMs, we discovered that baicalein, a specific flavonoid from Scutellaria baicalensis, targets S. Typhimurium pathogenicity island-1 (SPI-1) type III secretion system (T3SS) effectors and translocases to inhibit bacterial invasion of epithelial cells. Structurally related flavonoids present in other TCMs, such as quercetin, also inactivated the SPI-1 T3SS and attenuated S. Typhimurium invasion. Our results demonstrate that specific plant metabolites from TCMs can directly interfere with key bacterial virulence pathways and reveal a previously unappreciated mechanism of action for anti-infective medicinal plants.
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Affiliation(s)
- Lun K Tsou
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States.,Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes , Zhunan Town, Miaoli County 35053, Taiwan, R.O.C
| | - María Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Jordan RoseFigura
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Zhenrun J Zhang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Yen-Chih Wang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Jacob S Yount
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Matthew Lefebre
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Paul D Dossa
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Junya Kato
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Fulan Guan
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Wing Lam
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Yung-Chi Cheng
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Howard C Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
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Portaliou AG, Tsolis KC, Loos MS, Zorzini V, Economou A. Type III Secretion: Building and Operating a Remarkable Nanomachine. Trends Biochem Sci 2016; 41:175-189. [DOI: 10.1016/j.tibs.2015.09.005] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 09/16/2015] [Accepted: 09/18/2015] [Indexed: 12/21/2022]
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McShan AC, De Guzman RN. The bacterial type III secretion system as a target for developing new antibiotics. Chem Biol Drug Des 2015; 85:30-42. [PMID: 25521643 DOI: 10.1111/cbdd.12422] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 01/14/2023]
Abstract
Antibiotic resistance in pathogens requires new targets for developing novel antibacterials. The bacterial type III secretion system (T3SS) is an attractive target for developing antibacterials as it is essential in the pathogenesis of many Gram-negative bacteria. The T3SS consists of structural proteins, effectors, and chaperones. Over 20 different structural proteins assemble into a complex nanoinjector that punctures a hole on the eukaryotic cell membrane to allow the delivery of effectors directly into the host cell cytoplasm. Defects in the assembly and function of the T3SS render bacteria non-infective. Two major classes of small molecules, salicylidene acylhydrazides and thiazolidinones, have been shown to inhibit multiple genera of bacteria through the T3SS. Many additional chemically and structurally diverse classes of small molecule inhibitors of the T3SS have been identified as well. While specific targets within the T3SS of a few inhibitors have been suggested, the vast majority of specific protein targets within the T3SS remain to be identified or characterized. Other T3SS inhibitors include polymers, proteins, and polypeptides mimics. In addition, T3SS activity is regulated by its interaction with biologically relevant molecules, such as bile salts and sterols, which could serve as scaffolds for drug design.
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Affiliation(s)
- Andrew C McShan
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, USA
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Monlezun L, Liebl D, Fenel D, Grandjean T, Berry A, Schoehn G, Dessein R, Faudry E, Attree I. PscI is a type III secretion needle anchoring protein within vitropolymerization capacities. Mol Microbiol 2015; 96:419-36. [DOI: 10.1111/mmi.12947] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Laura Monlezun
- INSERM; UMR-S 1036; Biology of Cancer and Infection; Grenoble France
- CNRS; Bacterial Pathogenesis and Cellular Responses; ERL 5261 Grenoble France
- Université Grenoble Alpes; F-38041 Grenoble France
- CEA; DSV/iRTSV; F-38054 Grenoble France
| | - David Liebl
- INSERM; UMR-S 1036; Biology of Cancer and Infection; Grenoble France
- CNRS; Bacterial Pathogenesis and Cellular Responses; ERL 5261 Grenoble France
- Université Grenoble Alpes; F-38041 Grenoble France
- CEA; DSV/iRTSV; F-38054 Grenoble France
| | - Daphna Fenel
- Université Grenoble Alpes; Institut de Biologie Structurale (IBS); 71 avenue des Martyrs 38044 Grenoble France
- CNRS; IBS; F-38044 Grenoble France
- CEA; IBS; F-38044 Grenoble France
| | - Teddy Grandjean
- Groupe de Recherche Translationnelle de la Relation Hôte-Pathogène; Faculté de Médecine de l'Université de Lille; 59000 Lille France
| | - Alice Berry
- INSERM; UMR-S 1036; Biology of Cancer and Infection; Grenoble France
- CNRS; Bacterial Pathogenesis and Cellular Responses; ERL 5261 Grenoble France
- Université Grenoble Alpes; F-38041 Grenoble France
- CEA; DSV/iRTSV; F-38054 Grenoble France
| | - Guy Schoehn
- Université Grenoble Alpes; Institut de Biologie Structurale (IBS); 71 avenue des Martyrs 38044 Grenoble France
- CNRS; IBS; F-38044 Grenoble France
- CEA; IBS; F-38044 Grenoble France
- Unit for Virus Host Cell Interactions UMI 3265 (UJF-EMBL-CNRS); 38027 Grenoble France
| | - Rodrigue Dessein
- Groupe de Recherche Translationnelle de la Relation Hôte-Pathogène; Faculté de Médecine de l'Université de Lille; 59000 Lille France
| | - Eric Faudry
- INSERM; UMR-S 1036; Biology of Cancer and Infection; Grenoble France
- CNRS; Bacterial Pathogenesis and Cellular Responses; ERL 5261 Grenoble France
- Université Grenoble Alpes; F-38041 Grenoble France
- CEA; DSV/iRTSV; F-38054 Grenoble France
| | - Ina Attree
- INSERM; UMR-S 1036; Biology of Cancer and Infection; Grenoble France
- CNRS; Bacterial Pathogenesis and Cellular Responses; ERL 5261 Grenoble France
- Université Grenoble Alpes; F-38041 Grenoble France
- CEA; DSV/iRTSV; F-38054 Grenoble France
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Zhou X, Hu X, Li J, Wang N. A Novel Periplasmic Protein, VrpA, Contributes to Efficient Protein Secretion by the Type III Secretion System in Xanthomonas spp. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:143-153. [PMID: 25338144 DOI: 10.1094/mpmi-10-14-0309-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Efficient secretion of type III effector proteins from the bacterial cytoplasm to host cell cytosol via a type III secretion system (T3SS) is crucial for virulence of plant-pathogenic bacterium. Our previous study revealed a conserved hypothetical protein, virulence-related periplasm protein A (VrpA), which was identified as a critical virulence factor for Xanthomonas citri subsp. citri. In this study, we demonstrate that mutation of vrpA compromises X. citri subsp. citri virulence and hypersensitive response induction. This deficiency is also observed in the X. campestris pv. campestris strain, suggesting a functional conservation of VrpA in Xanthomonas spp. Our study indicates that VrpA is required for efficient protein secretion via T3SS, which is supported by multiple lines of evidence. A CyaA reporter assay shows that VrpA is involved in type III effector secretion; quantitative reverse-transcription polymerase chain reaction analysis suggests that the vrpA mutant fails to activate citrus-canker-susceptible gene CsLOB1, which is transcriptionally activated by transcription activator-like effector PthA4; in vitro secretion study reveals that VrpA plays an important role in secretion of T3SS pilus, translocon, and effector proteins. Our data also indicate that VrpA in X. citri subsp. citri localizes to bacterial periplasmic space and the periplasmic localization is required for full function of VrpA and X. citri subsp. citri virulence. Protein-protein interaction studies show that VrpA physically interacts with periplasmic T3SS components HrcJ and HrcC. However, the mutation of VrpA does not affect T3SS gene expression. Additionally, VrpA is involved in X. citri subsp. citri tolerance of oxidative stress. Our data contribute to the mechanical understanding of an important periplasmic protein VrpA in Xanthomonas spp.
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Carden S, Okoro C, Dougan G, Monack D. Non-typhoidal Salmonella Typhimurium ST313 isolates that cause bacteremia in humans stimulate less inflammasome activation than ST19 isolates associated with gastroenteritis. Pathog Dis 2014; 73:ftu023. [PMID: 25808600 PMCID: PMC4399442 DOI: 10.1093/femspd/ftu023] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2014] [Indexed: 02/07/2023] Open
Abstract
Salmonella is an enteric pathogen that causes a range of diseases in humans. Non-typhoidal Salmonella (NTS) serovars such as Salmonella enterica serovar Typhimurium generally cause a self-limiting gastroenteritis whereas typhoidal serovars cause a systemic disease, typhoid fever. However, S. Typhimurium isolates within the multi-locus sequence type ST313 have emerged in sub-Saharan Africa as a major cause of bacteremia in humans. The S. Typhimurium ST313 lineage is phylogenetically distinct from classical S. Typhimurium lineages, such as ST19, that cause zoonotic gastroenteritis worldwide. Previous studies have shown that the ST313 lineage has undergone genome degradation when compared to the ST19 lineage, similar to that observed for typhoidal serovars. Currently, little is known about phenotypic differences between ST313 isolates and other NTS isolates. We find that representative ST313 isolates invade non-phagocytic cells less efficiently than the classical ST19 isolates that are more commonly associated with gastroenteritis. In addition, ST313 isolates induce less Caspase-1-dependent macrophage death and IL-1β release than ST19 isolates. ST313 isolates also express relatively lower levels of mRNA of the genes encoding the SPI-1 effector sopE2 and the flagellin, fliC, providing possible explanations for the decrease in invasion and inflammasome activation. The ST313 isolates have invasion and inflammatory phenotypes that are intermediate; more invasive and inflammatory than Salmonella enterica serovar Typhi and less than ST19 isolates associated with gastroenteritis. This suggests that both phenotypically and at the genomic level ST313 isolates are evolving signatures that facilitate a systemic lifestyle in humans.
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Affiliation(s)
- Sarah Carden
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Chinyere Okoro
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Denise Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Galán JE, Lara-Tejero M, Marlovits TC, Wagner S. Bacterial type III secretion systems: specialized nanomachines for protein delivery into target cells. Annu Rev Microbiol 2014; 68:415-38. [PMID: 25002086 DOI: 10.1146/annurev-micro-092412-155725] [Citation(s) in RCA: 367] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
One of the most exciting developments in the field of bacterial pathogenesis in recent years is the discovery that many pathogens utilize complex nanomachines to deliver bacterially encoded effector proteins into target eukaryotic cells. These effector proteins modulate a variety of cellular functions for the pathogen's benefit. One of these protein-delivery machines is the type III secretion system (T3SS). T3SSs are widespread in nature and are encoded not only by bacteria pathogenic to vertebrates or plants but also by bacteria that are symbiotic to plants or insects. A central component of T3SSs is the needle complex, a supramolecular structure that mediates the passage of the secreted proteins across the bacterial envelope. Working in conjunction with several cytoplasmic components, the needle complex engages specific substrates in sequential order, moves them across the bacterial envelope, and ultimately delivers them into eukaryotic cells. The central role of T3SSs in pathogenesis makes them great targets for novel antimicrobial strategies.
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Affiliation(s)
- Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut 06536;
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Diepold A, Wagner S. Assembly of the bacterial type III secretion machinery. FEMS Microbiol Rev 2014; 38:802-22. [PMID: 24484471 DOI: 10.1111/1574-6976.12061] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 01/02/2014] [Accepted: 01/13/2014] [Indexed: 11/29/2022] Open
Abstract
Many bacteria that live in contact with eukaryotic hosts, whether as symbionts or as pathogens, have evolved mechanisms that manipulate host cell behaviour to their benefit. One such mechanism, the type III secretion system, is employed by Gram-negative bacterial species to inject effector proteins into host cells. This function is reflected by the overall shape of the machinery, which resembles a molecular syringe. Despite the simplicity of the concept, the type III secretion system is one of the most complex known bacterial nanomachines, incorporating one to more than hundred copies of up to twenty different proteins into a multi-MDa transmembrane complex. The structural core of the system is the so-called needle complex that spans the bacterial cell envelope as a tripartite ring system and culminates in a needle protruding from the bacterial cell surface. Substrate targeting and translocation are accomplished by an export machinery consisting of various inner membrane embedded and cytoplasmic components. The formation of such a multimembrane-spanning machinery is an intricate task that requires precise orchestration. This review gives an overview of recent findings on the assembly of type III secretion machines, discusses quality control and recycling of the system and proposes an integrated assembly model.
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Affiliation(s)
- Andreas Diepold
- Department of Biochemistry, University of Oxford, Oxford, UK
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Burkinshaw BJ, Strynadka NCJ. Assembly and structure of the T3SS. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1649-63. [PMID: 24512838 DOI: 10.1016/j.bbamcr.2014.01.035] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/27/2014] [Accepted: 01/29/2014] [Indexed: 02/06/2023]
Abstract
The Type III Secretion System (T3SS) is a multi-mega Dalton apparatus assembled from more than twenty components and is found in many species of animal and plant bacterial pathogens. The T3SS creates a contiguous channel through the bacterial and host membranes, allowing injection of specialized bacterial effector proteins directly to the host cell. In this review, we discuss our current understanding of T3SS assembly and structure, as well as highlight structurally characterized Salmonella effectors. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Brianne J Burkinshaw
- Department of Biochemistry and Molecular Biology, Center for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology, Center for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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The inner rod protein controls substrate switching and needle length in a Salmonella type III secretion system. Proc Natl Acad Sci U S A 2013; 111:817-22. [PMID: 24379359 DOI: 10.1073/pnas.1319698111] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Type III secretion machines are essential for the biology of many bacteria that are pathogenic or symbiotic for animals, plants, or insects. They exert their function by delivering bacterial effector proteins into target eukaryotic cells. The core component of these machines is the needle complex, a multiprotein structure that spans the bacterial envelope and serves as a conduit for proteins that transit this secretion pathway. The needle complex is composed of a multiring base embedded in the bacterial envelope and a filament-like structure, the needle, that projects from the bacterial surface and is linked to the base by the inner rod. Assembly of the needle complex proceeds in a step-wise fashion that is initiated by the assembly of the base and is followed by the export of the building subunits for the needle and inner rod substructures. Once assembled, the needle complex reprograms its specificity and becomes competent for the secretion of effector proteins. Here through genetic, biochemical, and electron microscopy analyses of the Salmonella inner rod protein subunit PrgJ we present evidence that the assembly of the inner rod dictates the timing of substrate switching and needle length. Furthermore, the identification of mutations in PrgJ that specifically alter the hierarchy of protein secretion provides additional support for a complex role of the inner rod substructure in type III secretion.
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Structure of a pathogenic type 3 secretion system in action. Nat Struct Mol Biol 2013; 21:82-7. [PMID: 24317488 DOI: 10.1038/nsmb.2722] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 10/22/2013] [Indexed: 12/20/2022]
Abstract
Type 3 secretion systems use 3.5-megadalton syringe-like, membrane-embedded 'injectisomes', each containing an ~800-Å-long needle complex to connect intracellular compartments of infectious bacteria and hosts. Here we identify requirements for substrate association with, transport through and exit from the injectisome of Salmonella enterica serovar Typhimurium. This guided the design of substrates that become trapped within the secretion path and enabled visualization of injectisomes in action in situ. We used cryo-EM to define the secretion path, providing a structural explanation as to why effector proteins must be unfolded during transport. Furthermore, trapping of a heterologous substrate in the needle prevents secretion of natural bacterial effectors. Together, the data reveal the path of protein secretion across multiple membranes and show that mechanisms rejecting unacceptable substrates can be undermined, and transport of bacterial effectors across an already assembled type 3 secretion system can be inhibited.
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Sarkar MK, Husnain SI, Jakubowski SJ, Christie PJ. Isolation of bacterial type IV machine subassemblies. Methods Mol Biol 2013; 966:187-204. [PMID: 23299736 DOI: 10.1007/978-1-62703-245-2_12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The bacterial type IV secretion systems (T4SSs) deliver DNA and protein substrates to bacterial and eukaryotic target cells generally by a mechanism requiring direct contact between donor and target cells. Recent advances in defining the architectures of T4SSs have been made through isolation of machine subassemblies for further biochemical and ultrastructural analysis. Here, we describe a protocol for isolation and characterization of VirB protein complexes from the paradigmatic VirB/VirD4 T4SS of Agrobacterium tumefaciens. This protocol can be adapted for isolation of T4SS subassemblies from other gram-negative bacteria as well as gram-positive bacteria. The biological importance of isolated T4SS subcomplexes can be assessed by assaying for copurification of trapped or cross-linked substrates. This can be achieved with a modified form of the chromatin immunoprecipitation (ChIP) assay termed transfer DNA immunoprecipitation (TrIP). Here, a TrIP protocol is described for recovery of formaldehyde-cross-linked DNA substrate-channel subunit complexes from cells employing T4SSs for conjugative DNA transfer.
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Affiliation(s)
- Mayukh K Sarkar
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX, USA
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Deletions in the pyruvate pathway of Salmonella Typhimurium alter SPI1-mediated gene expression and infectivity. J Anim Sci Biotechnol 2013; 4:5. [PMID: 23442379 PMCID: PMC3608087 DOI: 10.1186/2049-1891-4-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 02/20/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Salmonella enterica serovar Typhimurium is a major foodborne pathogen worldwide. S. Typhimurium encodes type III secretion systems via Salmonella pathogenicity islands (SPI), producing the major effector proteins of virulence. Previously, we identified two genes of Salmonella pyruvate metabolism that were up-regulated during chicken cell infection: pyruvate formate lyase I (pflB) and bifunctional acetaldehyde-CoA/alcohol dehydrogenase (adhE). We were therefore interested in examining the role these genes may play in the transmission of Salmonella to humans. METHODS Mutant strains of Salmonella with single gene deletions for pflB and adhE were created. Invasion and growth in human HCT-8 intestinal epithelial cells and THP-1 macrophages was examined. Quantitative PCR was performed on 19 SPI-1 genes. RESULTS In HCT-8 cells, both mutant strains had significantly higher intracellular counts than the wild-type from 4 to 48 h post-infection. Various SPI-1 genes in the mutants were up-regulated over the wild-type as early as 1 h and lasting until 24 h post-infection. In THP-1 cells, no significant difference in internal Salmonella counts was observed; however, SPI-1 genes were largely down-regulated in the mutants during the time-course of infection. We also found five SPI-1 genes - hilA, hilC hilD, sicP and rtsA - which were up-regulated in at least one of the mutant strains in log-phase broth cultures alone. We have therefore identified a set of SPI-1 virulence genes whose regulation is effected by the central metabolism of Salmonella.
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Identification of novel type III secretion chaperone-substrate complexes of Chlamydia trachomatis. PLoS One 2013; 8:e56292. [PMID: 23431368 PMCID: PMC3576375 DOI: 10.1371/journal.pone.0056292] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/07/2013] [Indexed: 12/17/2022] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterial pathogen of humans that uses a type III secretion (T3S) system to manipulate host cells through the delivery of effector proteins into their cytosol and membranes. The function of T3S systems depends on small bacterial cytosolic chaperone-like proteins, which bind T3S substrates and ensure their appropriate secretion. To find novel T3S chaperone-substrate complexes of C. trachomatis we first searched its genome for genes encoding proteins with features of T3S chaperones. We then systematically tested for interactions between candidate chaperones and chlamydial T3S substrates by bacterial two-hybrid. This revealed interactions between Slc1 (a known T3S chaperone) or CT584 and several T3S substrates. Co-immunoprecipation after protein expression in Yersinia enterocolitica and protein overlay binding assays indicated that Slc1 interacted with the N-terminal region of the known T3S substrates Tarp (a previously described substrate of Slc1), CT694, and CT695, and that CT584 interacted with a central region of CT082, which we identified as a C. trachomatis T3S substrate using Y. enterocolitica as a heterologous system. Further T3S assays in Yersinia indicated that Slc1 or CT584 increased the amount of secreted Tarp, CT694, and CT695, or CT082, respectively. Expression of CT584 increased the intra-bacterial stability of CT082, while Slc1 did not affect the stability of its substrates. Overall, this indicated that in C. trachomatis Slc1 is a chaperone of multiple T3S substrates and that CT584 is a chaperone of the newly identified T3S substrate CT082.
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Dehghani B, Rasooli I, Gargari SLM, Nadooshan MRJ, Owlia P, Nazarian S. Immunogenicity of Salmonella enterica serovar Enteritidis virulence protein, InvH, and cross-reactivity of its antisera with Salmonella strains. Microbiol Res 2013; 168:84-90. [PMID: 23141708 DOI: 10.1016/j.micres.2012.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 09/03/2012] [Accepted: 09/09/2012] [Indexed: 11/19/2022]
Affiliation(s)
- Behzad Dehghani
- Department of Biology, Shahed University, Tehran-Qom Express Way, Opposite Imam Khomeini's Shrine, Tehran 3319118651, Iran
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Flores-Kim J, Darwin AJ. Links between type III secretion and extracytoplasmic stress responses in Yersinia. Front Cell Infect Microbiol 2012; 2:125. [PMID: 23087910 PMCID: PMC3467454 DOI: 10.3389/fcimb.2012.00125] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 09/24/2012] [Indexed: 11/13/2022] Open
Abstract
The cell envelope of pathogenic bacteria is a barrier against host environmental conditions and immunity molecules, as well as the site where many virulence factors are assembled. Extracytoplasmic stress responses (ESRs) have evolved to help maintain its integrity in conditions where it might be compromised. These ESRs also have important links to the production of envelope-associated virulence systems by the bacteria themselves. One such virulence factor is the type III secretion system (T3SS), the first example of which was provided by the pathogenic Yersinia. This article reviews the reported links between four different ESRs and T3SS function in Yersinia. Components of three of these ESRs affect the function and/or regulation of two different T3SSs. The response regulator of the Rcs ESR is involved in positive regulation of the Ysa-Ysp T3SS found in the highly pathogenic 1B biogroup of Y. enterocolitica. Conversely, the response regulator of the Y. pseudotuberculosis Cpx ESR can down-regulate production of the Ysc-Yop T3SS, and at least one other envelope virulence factor (invasin), by direct repression. Also in Y. pseudotuberculosis, there is some evidence suggesting that an intact RpoE ESR might be important for normal Yersinia outer proteins (Yop) production and secretion. Besides these regulatory links between ESRs and T3SSs, perhaps the most striking connection between T3SS function and an ESR is that between the phage shock protein (Psp) and Ysc-Yop systems of Y. enterocolitica. The Psp response does not affect the regulation or function of the Ysc-Yop system. Instead, Ysc-Yop T3SS production induces the Psp system, which then mitigates T3SS-induced envelope stress. Consequently, the Y. enterocolitica Psp system is essential when the Ysc-Yop T3SS is produced.
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Affiliation(s)
- Josué Flores-Kim
- Department of Microbiology, New York University School of Medicine New York, NY, USA
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Protein export according to schedule: architecture, assembly, and regulation of type III secretion systems from plant- and animal-pathogenic bacteria. Microbiol Mol Biol Rev 2012; 76:262-310. [PMID: 22688814 DOI: 10.1128/mmbr.05017-11] [Citation(s) in RCA: 304] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Flagellar and translocation-associated type III secretion (T3S) systems are present in most gram-negative plant- and animal-pathogenic bacteria and are often essential for bacterial motility or pathogenicity. The architectures of the complex membrane-spanning secretion apparatuses of both systems are similar, but they are associated with different extracellular appendages, including the flagellar hook and filament or the needle/pilus structures of translocation-associated T3S systems. The needle/pilus is connected to a bacterial translocon that is inserted into the host plasma membrane and mediates the transkingdom transport of bacterial effector proteins into eukaryotic cells. During the last 3 to 5 years, significant progress has been made in the characterization of membrane-associated core components and extracellular structures of T3S systems. Furthermore, transcriptional and posttranscriptional regulators that control T3S gene expression and substrate specificity have been described. Given the architecture of the T3S system, it is assumed that extracellular components of the secretion apparatus are secreted prior to effector proteins, suggesting that there is a hierarchy in T3S. The aim of this review is to summarize our current knowledge of T3S system components and associated control proteins from both plant- and animal-pathogenic bacteria.
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Abby SS, Rocha EPC. The non-flagellar type III secretion system evolved from the bacterial flagellum and diversified into host-cell adapted systems. PLoS Genet 2012; 8:e1002983. [PMID: 23028376 PMCID: PMC3459982 DOI: 10.1371/journal.pgen.1002983] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 08/09/2012] [Indexed: 12/20/2022] Open
Abstract
Type 3 secretion systems (T3SSs) are essential components of two complex bacterial machineries: the flagellum, which drives cell motility, and the non-flagellar T3SS (NF-T3SS), which delivers effectors into eukaryotic cells. Yet the origin, specialization, and diversification of these machineries remained unclear. We developed computational tools to identify homologous components of the two systems and to discriminate between them. Our analysis of >1,000 genomes identified 921 T3SSs, including 222 NF-T3SSs. Phylogenomic and comparative analyses of these systems argue that the NF-T3SS arose from an exaptation of the flagellum, i.e. the recruitment of part of the flagellum structure for the evolution of the new protein delivery function. This reconstructed chronology of the exaptation process proceeded in at least two steps. An intermediate ancestral form of NF-T3SS, whose descendants still exist in Myxococcales, lacked elements that are essential for motility and included a subset of NF-T3SS features. We argue that this ancestral version was involved in protein translocation. A second major step in the evolution of NF-T3SSs occurred via recruitment of secretins to the NF-T3SS, an event that occurred at least three times from different systems. In rhizobiales, a partial homologous gene replacement of the secretin resulted in two genes of complementary function. Acquisition of a secretin was followed by the rapid adaptation of the resulting NF-T3SSs to multiple, distinct eukaryotic cell envelopes where they became key in parasitic and mutualistic associations between prokaryotes and eukaryotes. Our work elucidates major steps of the evolutionary scenario leading to extant NF-T3SSs. It demonstrates how molecular evolution can convert one complex molecular machine into a second, equally complex machine by successive deletions, innovations, and recruitment from other molecular systems.
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Affiliation(s)
- Sophie S Abby
- Département Génomes et Génétique, Institut Pasteur, Microbial Evolutionary Genomics, Paris, France.
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