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Göser V, Sander N, Schulte M, Scharte F, Franzkoch R, Liss V, Psathaki OE, Hensel M. Single molecule analyses reveal dynamics of Salmonella translocated effector proteins in host cell endomembranes. Nat Commun 2023; 14:1240. [PMID: 36870997 PMCID: PMC9985595 DOI: 10.1038/s41467-023-36758-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 02/16/2023] [Indexed: 03/06/2023] Open
Abstract
The facultative intracellular pathogen Salmonella enterica remodels the host endosomal system for survival and proliferation inside host cells. Salmonella resides within the Salmonella-containing vacuole (SCV) and by Salmonella-induced fusions of host endomembranes, the SCV is connected with extensive tubular structures termed Salmonella-induced filaments (SIF). The intracellular lifestyle of Salmonella critically depends on effector proteins translocated into host cells. A subset of effectors is associated with, or integral in SCV and SIF membranes. How effectors reach their subcellular destination, and how they interact with endomembranes remodeled by Salmonella remains to be determined. We deployed self-labeling enzyme tags to label translocated effectors in living host cells, and analyzed their single molecule dynamics. Translocated effectors diffuse in membranes of SIF with mobility comparable to membrane-integral host proteins in endomembranes. Dynamics differ between various effectors investigated and is dependent on membrane architecture of SIF. In the early infection, host endosomal vesicles are associated with Salmonella effectors. Effector-positive vesicles continuously fuse with SCV and SIF membranes, providing a route of effector delivery by translocation, interaction with endosomal vesicles, and ultimately fusion with the continuum of SCV/SIF membranes. This mechanism controls membrane deformation and vesicular fusion to generate the specific intracellular niche for bacterial survival and proliferation.
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Affiliation(s)
- Vera Göser
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Nathalie Sander
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Marc Schulte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Felix Scharte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Rico Franzkoch
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.,iBiOs - Integrated Bioimaging Facility Osnabrück, Osnabrück, Germany
| | - Viktoria Liss
- iBiOs - Integrated Bioimaging Facility Osnabrück, Osnabrück, Germany
| | - Olympia E Psathaki
- iBiOs - Integrated Bioimaging Facility Osnabrück, Osnabrück, Germany.,CellNanOs - Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany. .,CellNanOs - Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany.
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2
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Barmherzig DA, Sun J. Towards practical holographic coherent diffraction imaging via maximum likelihood estimation. OPTICS EXPRESS 2022; 30:6886-6906. [PMID: 35299464 DOI: 10.1364/oe.445015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
A new algorithmic framework is developed for holographic coherent diffraction imaging (HCDI) based on maximum likelihood estimation (MLE). This method provides superior image reconstruction results for various practical HCDI settings, such as when data is highly corrupted by Poisson shot noise and when low-frequency data is missing due to occlusion from a beamstop apparatus. This method is also highly robust in that it can be implemented using a variety of standard numerical optimization algorithms, and requires fewer constraints on the physical HCDI setup compared to current algorithms. The mathematical framework developed using MLE is also applicable beyond HCDI to any holographic imaging setup where data is corrupted by Poisson shot noise.
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3
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Fang Z, Méresse S. Endomembrane remodeling and dynamics in Salmonella infection. MICROBIAL CELL (GRAZ, AUSTRIA) 2022; 9:24-41. [PMID: 35127930 PMCID: PMC8796136 DOI: 10.15698/mic2022.02.769] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 11/13/2022]
Abstract
Salmonellae are bacteria that cause moderate to severe infections in humans, depending on the strain and the immune status of the infected host. These pathogens have the particularity of residing in the cells of the infected host. They are usually found in a vacuolar compartment that the bacteria shape with the help of effector proteins. Following invasion of a eukaryotic cell, the bacterial vacuole undergoes maturation characterized by changes in localization, composition and morphology. In particular, membrane tubules stretching over the microtubule cytoskeleton are formed from the bacterial vacuole. Although these tubules do not occur in all infected cells, they are functionally important and promote intracellular replication. This review focuses on the role and significance of membrane compartment remodeling observed in infected cells and the bacterial and host cell pathways involved.
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Affiliation(s)
- Ziyan Fang
- Aix Marseille University, CNRS, INSERM, CIML, Marseille, France
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4
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Quantitative proteomic screen identifies annexin A2 as a host target for Salmonella pathogenicity island-2 effectors SopD2 and PipB2. Sci Rep 2021; 11:23630. [PMID: 34880286 PMCID: PMC8655068 DOI: 10.1038/s41598-021-02795-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 11/17/2021] [Indexed: 11/18/2022] Open
Abstract
Intracellular pathogens need to establish an intracellular replicative niche to promote survival and replication within the hostile environment inside the host cell. Salmonella enterica serovar Typhimurium (S. Typhimurium) initiates formation of the unique Salmonella-containing vacuole and an extensive network of Salmonella-induced tubules in order to survive and thrive within host cells. At least six effectors secreted by the type III secretion system encoded within Salmonella pathogenicity island-2 (SPI-2), namely SifA, SopD2, PipB2, SteA, SseJ, and SseF, purportedly manipulate host cell intracellular trafficking and establish the intracellular replicative niche for S. Typhimurium. The phenotypes of these effectors are both subtle and complex, complicating elucidation of the mechanism underpinning host cell manipulation by S. Typhimurium. In this work we used stable isotope labeling of amino acids in cell culture (SILAC) and a S. Typhimurium mutant that secretes increased amounts of effectors to identify cognate effector binding partners during infection. Using this method, we identified the host protein annexin A2 (AnxA2) as a binding partner for both SopD2 and PipB2 and were able to confirm its binding to SopD2 and PipB2 by reciprocal pull down, although there was a low level of non-specific binding of SopD2-2HA and PipB2-2HA to the Ni-Sepharose beads present. We further showed that knockdown of AnxA2 altered the intracellular positioning of the Salmonella containing vacuole (SCV). This suggests that AnxA2 plays a role in the subcellular positioning of the SCV which could potentially be mediated through protein–protein interactions with either SopD2 or PipB2. This demonstrates the value of studying effector interactions using proteomic techniques and natural effector delivery during infection rather than transfection.
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Reuter T, Scharte F, Franzkoch R, Liss V, Hensel M. Single cell analyses reveal distinct adaptation of typhoidal and non-typhoidal Salmonella enterica serovars to intracellular lifestyle. PLoS Pathog 2021; 17:e1009319. [PMID: 34143852 PMCID: PMC8244875 DOI: 10.1371/journal.ppat.1009319] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/30/2021] [Accepted: 05/14/2021] [Indexed: 01/06/2023] Open
Abstract
Salmonella enterica is a common foodborne, facultative intracellular enteropathogen. Human-restricted typhoidal S. enterica serovars Typhi (STY) or Paratyphi A (SPA) cause severe typhoid or paratyphoid fever, while many S. enterica serovar Typhimurium (STM) strains have a broad host range and in human hosts usually lead to a self-limiting gastroenteritis. Due to restriction of STY and SPA to primate hosts, experimental systems for studying the pathogenesis of typhoid and paratyphoid fever are limited. Therefore, STM infection of susceptible mice is commonly considered as model system for studying these diseases. The type III secretion system encoded by Salmonella pathogenicity island 2 (SPI2-T3SS) is a key factor for intracellular survival of Salmonella. Inside host cells, the pathogen resides within the Salmonella-containing vacuole (SCV) and induces tubular structures extending from the SCV, termed Salmonella-induced filaments (SIF). This study applies single cell analyses approaches, which are flow cytometry of Salmonella harboring dual fluorescent protein reporters, effector translocation, and correlative light and electron microscopy to investigate the fate and activities of intracellular STY and SPA. The SPI2-T3SS of STY and SPA is functional in translocation of effector proteins, SCV and SIF formation. However, only a low proportion of intracellular STY and SPA are actively deploying SPI2-T3SS and STY and SPA exhibited a rapid decline of protein biosynthesis upon experimental induction. A role of SPI2-T3SS for proliferation of STY and SPA in epithelial cells was observed, but not for survival or proliferation in phagocytic host cells. Our results indicate that reduced intracellular activities are factors of the stealth strategy of STY and SPA and facilitate systemic spread and persistence of the typhoidal Salmonella. Typhoidal Salmonella enterica serovars Typhi (STY) and Paratyphi A (SPA) cause a major disease burden to the human population. The restriction of these pathogens to human hosts limits experimental analyses of molecular mechanisms of diseases. S. enterica serovar Typhimurium is commonly used as surrogate model for typhoidal Salmonella (TS), and allowed the identification of virulence factors for intracellular lifestyle of S. enterica in mammalian host cells. If virulence factors, such as the Salmonella Pathogenicity Island 2-encoded type III secretion system (SPI2-T3SS) have similar roles for intracellular lifestyle of TS is largely unknown. We analyzed, on single cell level, the intracellular activities of STY and SPA in comparison to STM. STY and SPA deploy SPI2-T3SS to actively manipulate their host cells, but with far lower frequency than STM. Our work supports a model of TS as stealth pathogens that persist in host cells.
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Affiliation(s)
- Tatjana Reuter
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Felix Scharte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Rico Franzkoch
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- iBiOs–integrated Bioimaging Facility Osnabrück, Universität Osnabrück, Osnabrück, Germany
| | - Viktoria Liss
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- iBiOs–integrated Bioimaging Facility Osnabrück, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs–Center of Cellular Nanoanalytics Osnabrück, Universität Osnabrück, Osnabrück, Germany
- * E-mail:
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6
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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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7
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Sachdeva K, Sundaramurthy V. The Interplay of Host Lysosomes and Intracellular Pathogens. Front Cell Infect Microbiol 2020; 10:595502. [PMID: 33330138 PMCID: PMC7714789 DOI: 10.3389/fcimb.2020.595502] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/22/2020] [Indexed: 12/20/2022] Open
Abstract
Lysosomes are an integral part of the intracellular defense system against microbes. Lysosomal homeostasis in the host is adaptable and responds to conditions such as infection or nutritional deprivation. Pathogens such as Mycobacterium tuberculosis (Mtb) and Salmonella avoid lysosomal targeting by actively manipulating the host vesicular trafficking and reside in a vacuole altered from the default lysosomal trafficking. In this review, the mechanisms by which the respective pathogen containing vacuoles (PCVs) intersect with lysosomal trafficking pathways and maintain their distinctness are discussed. Despite such active inhibition of lysosomal targeting, emerging literature shows that different pathogens or pathogen derived products exhibit a global influence on the host lysosomal system. Pathogen mediated lysosomal enrichment promotes the trafficking of a sub-set of pathogens to lysosomes, indicating heterogeneity in the host-pathogen encounter. This review integrates recent advancements on the global lysosomal alterations upon infections and the host protective role of the lysosomes against these pathogens. The review also briefly discusses the heterogeneity in the lysosomal targeting of these pathogens and the possible mechanisms and consequences.
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8
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Knuff-Janzen K, Tupin A, Yurist-Doutsch S, Rowland JL, Finlay BB. Multiple Salmonella-pathogenicity island 2 effectors are required to facilitate bacterial establishment of its intracellular niche and virulence. PLoS One 2020; 15:e0235020. [PMID: 32584855 PMCID: PMC7316343 DOI: 10.1371/journal.pone.0235020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/05/2020] [Indexed: 12/31/2022] Open
Abstract
The pathogenesis of Salmonella Typhimurium depends on the
bacterium’s ability to survive and replicate within host cells. The formation
and maintenance of a unique membrane-bound compartment, termed the
Salmonella-containing vacuole (SCV), is essential for
S. Typhimurium pathogenesis. SCV-bound S.
Typhimurium induces formation of filamentous tubules that radiate outwards from
the SCV, termed Salmonella-induced filaments (SIFs). SIF
formation is concomitant with the onset of replication within host epithelial
cells. SIF biogenesis, formation and maintenance of the SCV, and the
intracellular positioning of the SCV within the host cell requires translocation
of bacterial proteins (effectors) into the host cell. Effectors secreted by the
type III secretion system encoded on Salmonella pathogenicity
island 2 (T3SS2) function to interfere with host cellular processes and promote
both intracellular survival and replication of S. Typhimurium.
Seven T3SS2-secreted effectors, SifA, SopD2, PipB2, SteA, SseJ, SseF, and SseG
have previously been implicated to play complementary, redundant, and/or
antagonistic roles with respect to SIF biogenesis, intracellular positioning of
the SCV, and SCV membrane dynamics modulation during infection. We undertook a
systematic study to delineate the contribution of each effector to these
processes by (i) deleting all seven of these effectors in a single
S. Typhimurium strain; and (ii) deleting combinations of
multiple effectors based on putative effector function. Using this deletion
mutant library, we show that each of SIF biogenesis, intracellular SCV
localization, intramacrophage replication, colonization, and virulence depends
on the activities of multiple effectors. Together, our data demonstrates the
complex interplay between these seven effectors and highlights the necessity to
study T3SS2-secreted effectors as groups, rather than studies of individual
effectors.
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Affiliation(s)
- Katelyn Knuff-Janzen
- Michael Smith Laboratories, University of British Columbia, Vancouver,
British Columbia, Canada
- Department of Microbiology & Immunology, University of British
Columbia, Vancouver, British Columbia, Canada
| | - Audrey Tupin
- Michael Smith Laboratories, University of British Columbia, Vancouver,
British Columbia, Canada
- Department of Microbiology & Immunology, University of British
Columbia, Vancouver, British Columbia, Canada
| | - Sophie Yurist-Doutsch
- Michael Smith Laboratories, University of British Columbia, Vancouver,
British Columbia, Canada
- Department of Microbiology & Immunology, University of British
Columbia, Vancouver, British Columbia, Canada
| | - Jennifer L. Rowland
- Michael Smith Laboratories, University of British Columbia, Vancouver,
British Columbia, Canada
- Department of Microbiology & Immunology, University of British
Columbia, Vancouver, British Columbia, Canada
| | - B. Brett Finlay
- Michael Smith Laboratories, University of British Columbia, Vancouver,
British Columbia, Canada
- Department of Microbiology & Immunology, University of British
Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, University of British
Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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9
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Varela-Chavez C, Blondel A, Popoff MR. Bacterial intracellularly active toxins: Membrane localisation of the active domain. Cell Microbiol 2020; 22:e13213. [PMID: 32353188 DOI: 10.1111/cmi.13213] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 04/06/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022]
Abstract
Numerous bacterial toxins exert their activity by inactivating or modulating a specific intracellular host target. For this purpose, these toxins have developed efficient strategies to overcome the different host cell defences including specific binding to cell surface, internalisation, passage through the endosome or plasma membrane, exploiting intracellular trafficking and addressing to intracellular targets. Several intracellularly active toxins deliver an active domain into the cytosol that interacts with a target localised to the inner face of the plasma membrane. Thus, the large clostridial glucosylating toxins (LCGTs) target Rho/Ras-GTPases, certain virulence factors of Gram negative bacteria, Rho-GTPases, while Pasteurella multocida toxin (PMT) targets trimeric G-proteins. Others such as botulinum neurotoxins and tetanus neurotoxin have their substrate on synaptic vesicle membrane. LCGTs, PMT, and certain virulence factors from Vibrio sp. show a particular structure constituted of a four-helix bundle membrane (4HBM) protruding from the catalytic site that specifically binds to the membrane phospholipids and then trap the catalytic domain at the proximity of the membrane anchored substrate. Structural and functional analysis indicate that the 4HBM tip of the Clostridium sordellii lethal toxin (TcsL) from the LCGT family contain two loops forming a cavity that mediates the binding to phospholipids and more specifically to phosphatidylserine.
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Affiliation(s)
| | - Arnaud Blondel
- Unité de Bio-Informatique Structurale, Institut Pasteur, Paris, France
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10
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Berglund J, Gjondrekaj R, Verney E, Maupin-Furlow JA, Edelmann MJ. Modification of the host ubiquitome by bacterial enzymes. Microbiol Res 2020; 235:126429. [PMID: 32109687 PMCID: PMC7369425 DOI: 10.1016/j.micres.2020.126429] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 02/03/2020] [Accepted: 02/09/2020] [Indexed: 12/14/2022]
Abstract
Attachment of ubiquitin molecules to protein substrates is a reversible post-translational modification (PTM), which occurs ubiquitously in eukaryotic cells and controls most cellular processes. As a consequence, ubiquitination is an attractive target of pathogen-encoded virulence factors. Pathogenic bacteria have evolved multiple mechanisms to hijack the host's ubiquitin system to their advantage. In this review, we discuss the bacteria-encoded E3 ligases and deubiquitinases translocated to the host for an addition or removal of eukaryotic ubiquitin modification, effectively hijacking the host's ubiquitination processes. We review bacterial enzymes homologous to host proteins in sequence and functions, as well as enzymes with novel mechanisms in ubiquitination, which have significant structural differences in comparison to the mammalian E3 ligases. Finally, we will also discuss examples of molecular "counter-weapons" - eukaryotic proteins, which counteract pathogen-encoded E3 ligases. The many examples of the pathogen effector molecules that catalyze eukaryotic ubiquitin modification bring to light the intricate pathways involved in the pathogenesis of some of the most virulent bacterial infections with human pathogens. The role of these effector molecules remains an essential determinant of bacterial virulence in terms of infection, invasion, and replication. A comprehensive understanding of the mechanisms dictating the mimicry employed by bacterial pathogens is of vital importance in developing new strategies for therapeutic approaches.
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Affiliation(s)
- Jennifer Berglund
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 1355 Museum Drive, Gainesville, 32611-0700, FL USA
| | - Rafaela Gjondrekaj
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 1355 Museum Drive, Gainesville, 32611-0700, FL USA
| | - Ellen Verney
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 1355 Museum Drive, Gainesville, 32611-0700, FL USA
| | - Julie A Maupin-Furlow
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 1355 Museum Drive, Gainesville, 32611-0700, FL USA
| | - Mariola J Edelmann
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, 1355 Museum Drive, Gainesville, 32611-0700, FL USA.
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11
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Wang M, Qazi IH, Wang L, Zhou G, Han H. Salmonella Virulence and Immune Escape. Microorganisms 2020; 8:microorganisms8030407. [PMID: 32183199 PMCID: PMC7143636 DOI: 10.3390/microorganisms8030407] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/02/2020] [Accepted: 03/10/2020] [Indexed: 02/07/2023] Open
Abstract
Salmonella genus represents the most common foodborne pathogens causing morbidity, mortality, and burden of disease in all regions of the world. The introduction of antimicrobial agents and Salmonella-specific phages has been considered as an effective intervention strategy to reduce Salmonella contamination. However, data from the United States, European countries, and low- and middle-income countries indicate that Salmonella cases are still a commonly encountered cause of bacterial foodborne diseases globally. The control programs have not been successful and even led to the emergence of some multidrug-resistant Salmonella strains. It is known that the host immune system is able to effectively prevent microbial invasion and eliminate microorganisms. However, Salmonella has evolved mechanisms of resisting host physical barriers and inhibiting subsequent activation of immune response through their virulence factors. There has been a high interest in understanding how Salmonella interacts with the host. Therefore, in the present review, we characterize the functions of Salmonella virulence genes and particularly focus on the mechanisms of immune escape in light of evidence from the emerging mainstream literature.
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Affiliation(s)
- Mengyao Wang
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Izhar Hyder Qazi
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China;
- Department of Veterinary Anatomy and Histology, Shaheed Benazir Bhutto University of Veterinary and Animal Sciences, Sakrand 67210, Pakistan
| | - Linli Wang
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Guangbin Zhou
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China;
- Correspondence: (H.H.); (G.Z.)
| | - Hongbing Han
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- Correspondence: (H.H.); (G.Z.)
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12
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The vacuole guard hypothesis: how intravacuolar pathogens fight to maintain the integrity of their beloved home. Curr Opin Microbiol 2020; 54:51-58. [PMID: 32044688 DOI: 10.1016/j.mib.2020.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 01/09/2020] [Indexed: 12/16/2022]
Abstract
Intravacuolar bacterial pathogens establish intracellular niches by constructing membrane-encompassed compartments. The vacuoles surrounding the bacteria are remarkably stable, facilitating microbial replication and preventing exposure to host cytoplasmically localized innate immune sensing mechanisms. To maintain integrity of the membrane compartment, the pathogen is armed with defensive weapons that prevent loss of vacuole integrity and potential exposure to host innate signaling. In some cases, the microbial components that maintain vacuolar integrity have been identified, but the basis for why the compartment degrades in their absence is unclear. In this review, we point out that lessons from the microbial-programmed degradation of the vacuole by the cytoplasmically localized Shigella flexneri provide crucial insights into how degradation of pathogen vacuoles occurs. We propose that in the absence of bacterial-encoded guard proteins, aberrant trafficking of host membrane-associated components results in a dysfunctional pathogen compartment. As a consequence, the vacuole is poisoned and replication is terminated.
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13
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Alghoribi MF, Doumith M, Alrodayyan M, Al Zayer M, Köster WL, Muhanna A, Aljohani SM, Balkhy HH, Desin TS. S. Enteritidis and S. Typhimurium Harboring SPI-1 and SPI-2 Are the Predominant Serotypes Associated With Human Salmonellosis in Saudi Arabia. Front Cell Infect Microbiol 2019; 9:187. [PMID: 31214517 PMCID: PMC6554431 DOI: 10.3389/fcimb.2019.00187] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 05/15/2019] [Indexed: 12/25/2022] Open
Abstract
Non-typhoidal Salmonella (NTS) strains are Gram negative bacterial pathogens that are associated with foodborne illness worldwide. During the process of infection, Salmonella uses two molecular injectisomes known as Type 3 Secretion Systems (T3SS) to secrete virulence factors that are encoded by Salmonella Pathogenicity Island-1 (SPI-1) and SPI-2 into host cells. These secretion systems play a major role in virulence, as shown in various animal models, but little is known about their role in human infections. In Saudi Arabia, NTS strains frequently cause human infections but data regarding these pathogenic strains is fairly limited. The aim of this study was to characterize Salmonella human clinical isolates in Riyadh, Saudi Arabia, by determining their serotype, testing for the presence of SPI-1 and SPI-2 genes and to determine the antibiotic resistance profiles of these strains. Using the rapid Check and Trace Salmonella™ (CTS) system our results demonstrate that S. Enteritidis and S. Typhimurium were the predominant serovars, followed by S. Livingstone, S. Kentucky and S. Poona among a list of 36 serovars reported for the first time in the country. In addition, SPI-1 genes were detected in 99% of the isolates, while the sifA gene (SPI-2) was not detected in 13.5% of the isolates. These results suggest that both the SPI-1 and SPI-2 virulence determinants are important for human infection. Moreover, we report the presence of a Multi-Drug (MDR) carbapenem resistant S. Kentucky isolate harboring the blaOXA−48 gene not reported previously in Saudi Arabia.
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Affiliation(s)
- Majed F Alghoribi
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Michel Doumith
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Maha Alrodayyan
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Maha Al Zayer
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Wolfgang L Köster
- Vaccine and Infectious Disease Organization-International Vaccine Center, University of Saskatchewan, Saskatoon, SK, Canada
| | - Abdulhai Muhanna
- John H. Stroger Junior Hospital of Cook County, Chicago, IL, United States
| | - Sameera M Aljohani
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia.,Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia
| | - Hanan H Balkhy
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia.,Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia
| | - Taseen S Desin
- King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
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14
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Masud S, Prajsnar TK, Torraca V, Lamers GE, Benning M, Van Der Vaart M, Meijer AH. Macrophages target Salmonella by Lc3-associated phagocytosis in a systemic infection model. Autophagy 2019; 15:796-812. [PMID: 30676840 PMCID: PMC6526873 DOI: 10.1080/15548627.2019.1569297] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/03/2019] [Accepted: 01/08/2019] [Indexed: 11/08/2022] Open
Abstract
Innate immune defense against intracellular pathogens, like Salmonella, relies heavily on the autophagy machinery of the host. This response is studied intensively in epithelial cells, the target of Salmonella during gastrointestinal infections. However, little is known of the role that autophagy plays in macrophages, the predominant carriers of this pathogen during systemic disease. Here we utilize a zebrafish embryo model to study the interaction of S. enterica serovar Typhimurium with the macroautophagy/autophagy machinery of macrophages in vivo. We show that phagocytosis of live but not heat-killed Salmonella triggers recruitment of the autophagy marker GFP-Lc3 in a variety of patterns labeling tight or spacious bacteria-containing compartments, also revealed by electron microscopy. Neutrophils display similar GFP-Lc3 associations, but genetic modulation of the neutrophil/macrophage balance and ablation experiments show that macrophages are critical for the defense response. Deficiency of atg5 reduces GFP-Lc3 recruitment and impairs host resistance, in contrast to atg13 deficiency, indicating that Lc3-Salmonella association at this stage is independent of the autophagy preinitiation complex and that macrophages target Salmonella by Lc3-associated phagocytosis (LAP). In agreement, GFP-Lc3 recruitment and host resistance are impaired by deficiency of Rubcn/Rubicon, known as a negative regulator of canonical autophagy and an inducer of LAP. We also found strict dependency on NADPH oxidase, another essential factor for LAP. Both Rubcn and NADPH oxidase are required to activate a Salmonella biosensor for reactive oxygen species inside infected macrophages. These results identify LAP as the major host protective autophagy-related pathway responsible for macrophage defense against Salmonella during systemic infection. Abbreviations: ATG: autophagy related gene; BECN1: Beclin 1; CFU: colony forming units; CYBA/P22PHOX: cytochrome b-245, alpha chain; CYBB/NOX2: cytochrome b-245 beta chain; dpf: days post fertilization; EGFP: enhanced green fluorescent protein; GFP: green fluorescent protein; hfp: hours post fertilization; hpi: hours post infection; IRF8: interferon regulatory factor 8; Lcp1/L-plastin: lymphocyte cytosolic protein 1; LAP: LC3-associated phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1A/1B-light chain 3; mCherry: red fluorescent protein; mpeg1: macrophage expressed gene 1; mpx: myeloid specific peroxidase; NADPH oxidase: nicotinamide adenine dinucleotide phosphate oxidase; NCF4/P40PHOX: neutrophil cytosolic factor 4; NTR-mCherry: nitroreductase-mCherry fusion; PTU: phenylthiourea; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; RB1CC1/FIP200: RB-1 inducible coiled coin 1; ROS: reactive oxygen species; RT-PCR: reverse transcriptase polymerase chain reaction; RUBCN/RUBICON: RUN and cysteine rich domain containing BECN1-interacting protein; SCV: Salmonella-containing vacuole; S. Typhimurium/S.T: Salmonella enterica serovar Typhimurium; TEM: transmission electron microscopy; Tg: transgenic; TSA: tyramide signal amplification; ULK1/2: unc-51-like autophagy activating kinase 1/2; UVRAG: UVRAG: UV radiation resistance associated; wt: wild type.
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Affiliation(s)
- Samrah Masud
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | | | - Vincenzo Torraca
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Gerda E.M. Lamers
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Marianne Benning
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
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15
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van Elsland D, Neefjes J. Bacterial infections and cancer. EMBO Rep 2018; 19:embr.201846632. [PMID: 30348892 PMCID: PMC6216254 DOI: 10.15252/embr.201846632] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 08/10/2018] [Accepted: 09/24/2018] [Indexed: 12/30/2022] Open
Abstract
Infections are estimated to contribute to 20% of all human tumours. These are mainly caused by viruses, which explains why a direct bacterial contribution to cancer formation has been largely ignored. While epidemiological data link bacterial infections to particular cancers, tumour formation is generally assumed to be solely caused by the ensuing inflammation responses. Yet, many bacteria directly manipulate their host cell in various phases of their infection cycle. Such manipulations can affect host cell integrity and can contribute to cancer formation. We here describe how bacterial surface moieties, bacterial protein toxins and bacterial effector proteins can induce host cell DNA damage, and thereby can interfere with essential host cell signalling pathways involved in cell proliferation, apoptosis, differentiation and immune signalling.
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Affiliation(s)
- Daphne van Elsland
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center LUMC, Leiden, The Netherlands
| | - Jacques Neefjes
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center LUMC, Leiden, The Netherlands
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16
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Nguyen SV, Harhay DM, Bono JL, Smith TPL, Fields PI, Dinsmore BA, Santovenia M, Wang R, Bosilevac JM, Harhay GP. Comparative genomics of Salmonella enterica serovar Montevideo reveals lineage-specific gene differences that may influence ecological niche association. Microb Genom 2018; 4:e000202. [PMID: 30052174 PMCID: PMC6159554 DOI: 10.1099/mgen.0.000202] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/05/2018] [Indexed: 01/01/2023] Open
Abstract
Salmonella enterica serovar Montevideo has been linked to recent foodborne illness outbreaks resulting from contamination of products such as fruits, vegetables, seeds and spices. Studies have shown that Montevideo also is frequently associated with healthy cattle and can be isolated from ground beef, yet human salmonellosis outbreaks of Montevideo associated with ground beef contamination are rare. This disparity fuelled our interest in characterizing the genomic differences between Montevideo strains isolated from healthy cattle and beef products, and those isolated from human patients and outbreak sources. To that end, we sequenced 13 Montevideo strains to completion, producing high-quality genome assemblies of isolates from human patients (n=8) or from healthy cattle at slaughter (n=5). Comparative analysis of sequence data from this study and publicly available sequences (n=72) shows that Montevideo falls into four previously established clades, differentially occupied by cattle and human strains. The results of these analyses reveal differences in metabolic islands, environmental adhesion determinants and virulence factors within each clade, and suggest explanations for the infrequent association between bovine isolates and human illnesses.
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Affiliation(s)
- Scott V. Nguyen
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland
| | - Dayna M. Harhay
- USDA-ARS-US Meat Animal Research Center, Clay Center, NE 68933, USA
| | - James L. Bono
- USDA-ARS-US Meat Animal Research Center, Clay Center, NE 68933, USA
| | | | - Patricia I. Fields
- Enteric Disease Laboratory Branch, Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Blake A. Dinsmore
- Enteric Disease Laboratory Branch, Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Monica Santovenia
- Enteric Disease Laboratory Branch, Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Rong Wang
- USDA-ARS-US Meat Animal Research Center, Clay Center, NE 68933, USA
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17
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Gao Y, Spahn C, Heilemann M, Kenney LJ. The Pearling Transition Provides Evidence of Force-Driven Endosomal Tubulation during Salmonella Infection. mBio 2018; 9:e01083-18. [PMID: 29921673 PMCID: PMC6016247 DOI: 10.1128/mbio.01083-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/13/2023] Open
Abstract
Bacterial pathogens exploit eukaryotic pathways for their own end. Upon ingestion, Salmonella enterica serovar Typhimurium passes through the stomach and then catalyzes its uptake across the intestinal epithelium. It survives and replicates in an acidic vacuole through the action of virulence factors secreted by a type three secretion system located on Salmonella pathogenicity island 2 (SPI-2). Two secreted effectors, SifA and SseJ, are sufficient for endosomal tubule formation, which modifies the vacuole and enables Salmonella to replicate within it. Two-color, superresolution imaging of the secreted virulence factor SseJ and tubulin revealed that SseJ formed clusters of conserved size at regular, periodic intervals in the host cytoplasm. Analysis of SseJ clustering indicated the presence of a pearling effect, which is a force-driven, osmotically sensitive process. The pearling transition is an instability driven by membranes under tension; it is induced by hypotonic or hypertonic buffer exchange and leads to the formation of beadlike structures of similar size and regular spacing. Reducing the osmolality of the fixation conditions using glutaraldehyde enabled visualization of continuous and intact tubules. Correlation analysis revealed that SseJ was colocalized with the motor protein kinesin. Tubulation of the endoplasmic reticulum is driven by microtubule motors, and in the present work, we describe how Salmonella has coopted the microtubule motor kinesin to drive the force-dependent process of endosomal tubulation. Thus, endosomal tubule formation is a force-driven process catalyzed by Salmonella virulence factors secreted into the host cytoplasm during infection.IMPORTANCE This study represents the first example of using two-color, superresolution imaging to analyze the secretion of Salmonella virulence factors as they are secreted from the SPI-2 type three secretion system. Previous studies imaged effectors that were overexpressed in the host cytoplasm. The present work reveals an unusual force-driven process, the pearling transition, which indicates that Salmonella-induced filaments are under force through the interactions of effector molecules with the motor protein kinesin. This work provides a caution by highlighting how fixation conditions can influence the images observed.
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Affiliation(s)
- Yunfeng Gao
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Christoph Spahn
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany
| | - Linda J Kenney
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
- Jesse Brown VA Medical Center, Chicago, Illinois, USA
- Department of Microbiology and Immunology, University of Illinois-Chicago, Chicago, Illinois, USA
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18
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Ingram JP, Tursi S, Zhang T, Guo W, Yin C, A Wynosky-Dolfi M, van der Heijden J, Cai KQ, Yamamoto M, Finlay BB, Brodsky IE, Grivennikov SI, Tükel Ç, Balachandran S. A Nonpyroptotic IFN-γ-Triggered Cell Death Mechanism in Nonphagocytic Cells Promotes Salmonella Clearance In Vivo. THE JOURNAL OF IMMUNOLOGY 2018; 200:3626-3634. [PMID: 29654208 DOI: 10.4049/jimmunol.1701386] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 03/21/2018] [Indexed: 01/14/2023]
Abstract
The cytokine IFN-γ has well-established antibacterial properties against the bacterium Salmonella enterica in phagocytes, but less is known about the effects of IFN-γ on Salmonella-infected nonphagocytic cells, such as intestinal epithelial cells (IECs) and fibroblasts. In this article, we show that exposing human and murine IECs and fibroblasts to IFN-γ following infection with Salmonella triggers a novel form of cell death that is neither pyroptosis nor any of the major known forms of programmed cell death. Cell death required IFN-γ-signaling via STAT1-IRF1-mediated induction of guanylate binding proteins and the presence of live Salmonella in the cytosol. In vivo, ablating IFN-γ signaling selectively in murine IECs led to higher bacterial burden in colon contents and increased inflammation in the intestine of infected mice. Together, these results demonstrate that IFN-γ signaling triggers release of Salmonella from the Salmonella-containing vacuole into the cytosol of infected nonphagocytic cells, resulting in a form of nonpyroptotic cell death that prevents bacterial spread in the gut.
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Affiliation(s)
- Justin P Ingram
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - Sarah Tursi
- Department of Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140
| | - Ting Zhang
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - Wei Guo
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA 19111.,Department of General Surgery, Qilu Hospital of Shandong University, Jinan 250012, China
| | - Chaoran Yin
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - Meghan A Wynosky-Dolfi
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104
| | - Joris van der Heijden
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T1Z4, Canada
| | - Kathy Q Cai
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA 19111; and
| | - Masahiro Yamamoto
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University Suita, Osaka 565-0871, Japan
| | - B Brett Finlay
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T1Z4, Canada
| | - Igor E Brodsky
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104
| | - Sergei I Grivennikov
- Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - Çagla Tükel
- Department of Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140
| | - Siddharth Balachandran
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111;
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19
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Salmonella exploits the host endolysosomal tethering factor HOPS complex to promote its intravacuolar replication. PLoS Pathog 2017; 13:e1006700. [PMID: 29084291 PMCID: PMC5679646 DOI: 10.1371/journal.ppat.1006700] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 11/09/2017] [Accepted: 10/18/2017] [Indexed: 12/22/2022] Open
Abstract
Salmonella enterica serovar typhimurium extensively remodels the host late endocytic compartments to establish its vacuolar niche within the host cells conducive for its replication, also known as the Salmonella-containing vacuole (SCV). By maintaining a prolonged interaction with late endosomes and lysosomes of the host cells in the form of interconnected network of tubules (Salmonella-induced filaments or SIFs), Salmonella gains access to both membrane and fluid-phase cargo from these compartments. This is essential for maintaining SCV membrane integrity and for bacterial intravacuolar nutrition. Here, we have identified the multisubunit lysosomal tethering factor—HOPS (HOmotypic fusion and Protein Sorting) complex as a crucial host factor facilitating delivery of late endosomal and lysosomal content to SCVs, providing membrane for SIF formation, and nutrients for intravacuolar bacterial replication. Accordingly, depletion of HOPS subunits significantly reduced the bacterial load in non-phagocytic and phagocytic cells as well as in a mouse model of Salmonella infection. We found that Salmonella effector SifA in complex with its binding partner; SKIP, interacts with HOPS subunit Vps39 and mediates recruitment of this tethering factor to SCV compartments. The lysosomal small GTPase Arl8b that binds to, and promotes membrane localization of Vps41 (and other HOPS subunits) was also required for HOPS recruitment to SCVs and SIFs. Our findings suggest that Salmonella recruits the host late endosomal and lysosomal membrane fusion machinery to its vacuolar niche for access to host membrane and nutrients, ensuring its intracellular survival and replication. Intracellular pathogens have devised various strategies to subvert the host membrane trafficking pathways for their growth and survival inside the host cells. Salmonella is one such successful intracellular pathogen that redirects membrane and nutrients from the host endocytic compartments to its replicative niche known as the Salmonella-containing vacuole (SCV) via establishing an interconnected network of tubules (Salmonella-induced filaments or SIFs) that form a continuum with the SCVs. How Salmonella ensures a constant supply of endocytic cargo required for its survival and growth remained unexplored. Our work uncovers a strategy evolved by Salmonella wherein it secretes a bacterial effector into the host cytosol that recruits component of host vesicle fusion machinery-HOPS complex to SCVs and SIFs. HOPS complex promotes docking of the late endocytic compartments at the SCV membrane, prior to their fusion. Thus, depletion of HOPS subunits both in cultured cell lines as well as a mouse model inhibits Salmonella replication, likely due to reduced access to host membranes and nutrients by the vacuolar bacteria. These findings provide mechanistic insights into how this pathogen reroutes the host’s endocytic transport towards its vacuole, ensuring its own intracellular survival and replication.
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20
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Namakchian M, Kassler K, Sticht H, Hensel M, Deiwick J. Structure-based functional analysis of effector protein SifA in living cells reveals motifs important for Salmonella intracellular proliferation. Int J Med Microbiol 2017; 308:84-96. [PMID: 28939436 DOI: 10.1016/j.ijmm.2017.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 09/02/2017] [Accepted: 09/04/2017] [Indexed: 02/01/2023] Open
Abstract
The facultative intracellular pathogen Salmonella enterica survives and replicates inside the Salmonella-containing vacuole (SCV) of mammalian host cells. SifA is a key effector protein translocated by a type III secretion system and involved in formation of Salmonella-induced filaments (SIF), extensive tubular endosomal compartments. Recruitment of LAMP1 (lysosomal-associated membrane protein 1)-positive membranes to SIF ensures integrity and dynamics of the membrane network. The binding of SifA to the host protein SKIP (SifA and kinesin interacting protein) was proposed as crucial for this function. Due to structural mimicry SifA has further been proposed to interact with G-proteins. We conducted a mutational study of SifA to identify domains and amino acid residues specifically relevant for intracellular replication and SIF formation. Mutations were designed based on the available structural data of SifA and its interface with SKIP, or modeled for SifA as putative guanine nucleotide exchange factor. We developed a live cell imaging-based approach for volume quantification of the SIF network that allowed determination of subtle changes in SIF network and performed a comprehensive analysis of mutant forms of SifA by this approach. We found that the SifA catalytic loop of WxxxE effectors is as important for SIF formation and intracellular proliferation as the SKIP interaction motif, or the CAAX motif for membrane anchoring of SifA.
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Affiliation(s)
| | - Kristin Kassler
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Heinrich Sticht
- Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
| | - Jörg Deiwick
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
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21
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Young AM, Minson M, McQuate SE, Palmer AE. Optimized Fluorescence Complementation Platform for Visualizing Salmonella Effector Proteins Reveals Distinctly Different Intracellular Niches in Different Cell Types. ACS Infect Dis 2017; 3:575-584. [PMID: 28551989 PMCID: PMC5720895 DOI: 10.1021/acsinfecdis.7b00052] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The bacterial pathogen Salmonella uses sophisticated type III secretion systems (T3SS) to translocate and deliver bacterial effector proteins into host cells to establish infection. Monitoring these important virulence determinants in the context of live infections is a key step in defining the dynamic interface between the host and pathogen. Here, we provide a modular labeling platform based on fluorescence complementation with split-GFP that permits facile tagging of new Salmonella effector proteins. We demonstrate enhancement of split-GFP complementation signals by manipulating the promoter or by multimerizing the fluorescent tag and visualize three effector proteins, SseF, SseG, and SlrP, that have never before been visualized over time during infection of live cells. Using this platform, we developed a methodology for visualizing effector proteins in primary macrophage cells for the first time and reveal distinct differences in the effector-defined intracellular niche between primary macrophage and commonly used HeLa and RAW cell lines.
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Affiliation(s)
- Alexandra M. Young
- Department of Chemistry and Biochemistry, BioFrontiers Institute, UCB 596, 3415 Colorado Ave, University of Colorado, Boulder, CO 80303
| | - Michael Minson
- Department of Chemistry and Biochemistry, BioFrontiers Institute, UCB 596, 3415 Colorado Ave, University of Colorado, Boulder, CO 80303
| | - Sarah E. McQuate
- Department of Chemistry and Biochemistry, BioFrontiers Institute, UCB 596, 3415 Colorado Ave, University of Colorado, Boulder, CO 80303
| | - Amy E. Palmer
- Department of Chemistry and Biochemistry, BioFrontiers Institute, UCB 596, 3415 Colorado Ave, University of Colorado, Boulder, CO 80303
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22
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Young AM, Palmer AE. Methods to Illuminate the Role of Salmonella Effector Proteins during Infection: A Review. Front Cell Infect Microbiol 2017; 7:363. [PMID: 28848721 PMCID: PMC5554337 DOI: 10.3389/fcimb.2017.00363] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 07/27/2017] [Indexed: 12/19/2022] Open
Abstract
Intracellular bacterial pathogens like Salmonella enterica use secretion systems, such as the Type III Secretion System, to deliver virulence factors into host cells in order to invade and colonize these cells. Salmonella virulence factors include a suite of effector proteins that remodel the host cell to facilitate bacterial internalization, replication, and evasion of host immune surveillance. A number of diverse and innovative approaches have been used to identify and characterize the role of effector proteins during infection. Recent techniques for studying infection using single cell and animal models have illuminated the contribution of individual effector proteins in infection. This review will highlight the techniques applied to study Salmonella effector proteins during infection. It will describe how different approaches have revealed mechanistic details for effectors in manipulating host cellular processes including: the dynamics of effector translocation into host cells, cytoskeleton reorganization, membrane trafficking, gene regulation, and autophagy.
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Affiliation(s)
- Alexandra M Young
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado BoulderBoulder, CO, United States
| | - Amy E Palmer
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado BoulderBoulder, CO, United States
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23
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Knuff K, Finlay BB. What the SIF Is Happening-The Role of Intracellular Salmonella-Induced Filaments. Front Cell Infect Microbiol 2017; 7:335. [PMID: 28791257 PMCID: PMC5524675 DOI: 10.3389/fcimb.2017.00335] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/10/2017] [Indexed: 11/29/2022] Open
Abstract
A common strategy among intracellular bacterial pathogens is to enter into a vacuolar environment upon host cell invasion. One such pathogen, Salmonella enterica, resides within the Salmonella-containing vacuole (SCV) inside epithelial cells and macrophages. Salmonella hijacks the host endosomal system to establish this unique intracellular replicative niche, forming a highly complex and dynamic network of Salmonella-induced filaments (SIFs). SIFs radiate outwards from the SCV upon onset of bacterial replication. SIF biogenesis is dependent on the activity of bacterial effector proteins secreted by the Salmonella-pathogenicity island-2 (SPI-2) encoded type III secretion system. While the presence of SIFs has been known for almost 25 years, their precise role during infection remains elusive. This review summarizes our current knowledge of SCV maturation and SIF biogenesis, and recent advances in our understanding of the role of SIFs inside cells.
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Affiliation(s)
- Katelyn Knuff
- Michael Smith Laboratories, University of British ColumbiaVancouver, BC, Canada.,Department of Microbiology and Immunology, University of British ColumbiaVancouver, BC, Canada
| | - B Brett Finlay
- Michael Smith Laboratories, University of British ColumbiaVancouver, BC, Canada.,Department of Microbiology and Immunology, University of British ColumbiaVancouver, BC, Canada.,Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
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Liss V, Swart AL, Kehl A, Hermanns N, Zhang Y, Chikkaballi D, Böhles N, Deiwick J, Hensel M. Salmonella enterica Remodels the Host Cell Endosomal System for Efficient Intravacuolar Nutrition. Cell Host Microbe 2017; 21:390-402. [DOI: 10.1016/j.chom.2017.02.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/04/2016] [Accepted: 02/02/2017] [Indexed: 01/09/2023]
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López-Montero N, Ramos-Marquès E, Risco C, García-Del Portillo F. Intracellular Salmonella induces aggrephagy of host endomembranes in persistent infections. Autophagy 2016; 12:1886-1901. [PMID: 27485662 DOI: 10.1080/15548627.2016.1208888] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Xenophagy has been studied in epithelial cells infected with Salmonella enterica serovar Typhimurium (S. Typhimurium). Distinct autophagy receptors target this pathogen to degradation after interacting with ubiquitin on the surface of cytosolic bacteria, and the phagophore- and autophagosome-associated protein MAP1LC3/LC3. Glycans exposed in damaged phagosomal membranes and diacylglycerol accumulation in the phagosomal membrane also trigger S. Typhimurium xenophagy. How these responses control intraphagosomal and cytosolic bacteria remains poorly understood. Here, we examined S. Typhimurium interaction with autophagy in fibroblasts, in which the pathogen displays limited growth and does not escape into the cytosol. Live-cell imaging microscopy revealed that S. Typhimurium recruits late endosomal or lysosomal compartments that evolve into a membranous aggregate connected to the phagosome. Active dynamics and integrity of the phagosomal membrane are requisite to induce such aggregates. This membranous structure increases over time to become an aggresome that engages autophagy machinery at late infection times (> 6 h postentry). The newly formed autophagosome harbors LC3 and the autophagy receptor SQSTM1/p62 but is devoid of ubiquitin and the receptor CALCOCO2/NDP52. Live-cell imaging showed that this autophagosome captures and digests within the same vacuole the aggresome and some apposed intraphagosomal bacteria. Other phagosomes move away from the aggresome and avoid destruction. Thus, host endomembrane accumulation resulting from activity of intracellular S. Typhimurium stimulates a novel type of aggrephagy that acts independently of ubiquitin and CALCOCO2, and destroys only a few bacteria. Such selective degradation might allow the pathogen to reduce its progeny and, as a consequence, to establish persistent infections.
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Affiliation(s)
- Noelia López-Montero
- a Laboratory of Intracellular Bacterial Pathogens, Department of Microbial Biotechnology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC) , Madrid , Spain
| | - Estel Ramos-Marquès
- a Laboratory of Intracellular Bacterial Pathogens, Department of Microbial Biotechnology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC) , Madrid , Spain
| | - Cristina Risco
- b Cell Structure Laboratory, Department of Macromolecular Structures, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC) , Madrid , Spain
| | - Francisco García-Del Portillo
- a Laboratory of Intracellular Bacterial Pathogens, Department of Microbial Biotechnology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC) , Madrid , Spain
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McQuate SE, Young AM, Silva-Herzog E, Bunker E, Hernandez M, de Chaumont F, Liu X, Detweiler CS, Palmer AE. Long-term live-cell imaging reveals new roles for Salmonella effector proteins SseG and SteA. Cell Microbiol 2016; 19. [PMID: 27376507 DOI: 10.1111/cmi.12641] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 06/08/2016] [Accepted: 06/28/2016] [Indexed: 01/18/2023]
Abstract
Salmonella Typhimurium is an intracellular bacterial pathogen that infects both epithelial cells and macrophages. Salmonella effector proteins, which are translocated into the host cell and manipulate host cell components, control the ability to replicate and/or survive in host cells. Due to the complexity and heterogeneity of Salmonella infections, there is growing recognition of the need for single-cell and live-cell imaging approaches to identify and characterize the diversity of cellular phenotypes and how they evolve over time. Here, we establish a pipeline for long-term (17 h) live-cell imaging of infected cells and subsequent image analysis methods. We apply this pipeline to track bacterial replication within the Salmonella-containing vacuole in epithelial cells, quantify vacuolar replication versus survival in macrophages and investigate the role of individual effector proteins in mediating these parameters. This approach revealed that dispersed bacteria can coalesce at later stages of infection, that the effector protein SseG influences the propensity for cytosolic hyper-replication in epithelial cells, and that while SteA only has a subtle effect on vacuolar replication in epithelial cells, it has a profound impact on infection parameters in immunocompetent macrophages, suggesting differential roles for effector proteins in different infection models.
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Affiliation(s)
- Sarah E McQuate
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Alexandra M Young
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Eugenia Silva-Herzog
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Eric Bunker
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Mateo Hernandez
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | | | - Xuedong Liu
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Corrella S Detweiler
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Amy E Palmer
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
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27
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Liss V, Hensel M. Take the tube: remodelling of the endosomal system by intracellularSalmonella enterica. Cell Microbiol 2015; 17:639-47. [DOI: 10.1111/cmi.12441] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/10/2015] [Accepted: 03/19/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Viktoria Liss
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie; Universität Osnabrück; Barbarastr. 11 Osnabrück 49076 Germany
| | - Michael Hensel
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie; Universität Osnabrück; Barbarastr. 11 Osnabrück 49076 Germany
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28
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Reorganization of the endosomal system in Salmonella-infected cells: the ultrastructure of Salmonella-induced tubular compartments. PLoS Pathog 2014; 10:e1004374. [PMID: 25254663 PMCID: PMC4177991 DOI: 10.1371/journal.ppat.1004374] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 08/03/2014] [Indexed: 12/03/2022] Open
Abstract
During the intracellular life of Salmonella enterica, a unique membrane-bound compartment termed Salmonella-containing vacuole, or SCV, is formed. By means of translocated effector proteins, intracellular Salmonella also induce the formation of extensive, highly dynamic membrane tubules termed Salmonella-induced filaments or SIF. Here we report the first detailed ultrastructural analyses of the SCV and SIF by electron microscopy (EM), EM tomography and live cell correlative light and electron microscopy (CLEM). We found that a subset of SIF is composed of double membranes that enclose portions of host cell cytosol and cytoskeletal filaments within its inner lumen. Despite some morphological similarities, we found that the formation of SIF double membranes is independent from autophagy and requires the function of the effector proteins SseF and SseG. The lumen of SIF network is accessible to various types of endocytosed material and our CLEM analysis of double membrane SIF demonstrated that fluid phase markers accumulate only between the inner and outer membrane of these structures, a space continual with endosomal lumen. Our work reveals how manipulation of the endosomal membrane system by an intracellular pathogen results in a unique tubular membrane compartmentalization of the host cell, generating a shielded niche permissive for intracellular proliferation of Salmonella. Salmonella enterica is an invasive, facultative intracellular bacterial pathogen. Within mammalian host cells, Salmonella inhabits a specialized membrane-bound compartment, the Salmonella-containing vacuole (SCV), redirects host cell vesicular transport and massively remodels the endosomal system. These activities depend on the function of a type III secretion system and its translocated effector proteins. Intracellular Salmonella induces several types of tubular compartments termed Salmonella-induced tubules (SIT), but the biogenesis and biological function of SIT is only partially understood. Our work combines live cell imaging with correlative light and electron microscopy to provide ultrastructural insight into SIT. We report that SIT emerge as single membrane tubules that convert into double membrane tubules entrapping cytosol and cytoskeletal filaments. Labeling of the endosomal compartment and cytochemistry demonstrate that the space between inner and outer SIT membrane is composed of internalized material and connected to Salmonella within the SCV. The effector proteins SseF and SseG translocated by intracellular Salmonella are essential for the conversion of single to double membrane SIT. These findings challenge current models for the intracellular lifestyle of Salmonella and the composition of its intracellular habitat.
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