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Yang W, Feng Y, Yan J, Kang C, Yao T, Sun H, Cheng Z. Phosphate (Pi) Transporter PIT1 Induces Pi Starvation in Salmonella-Containing Vacuole in HeLa Cells. Int J Mol Sci 2023; 24:17216. [PMID: 38139044 PMCID: PMC10743064 DOI: 10.3390/ijms242417216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/04/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium), an important foodborne pathogen, causes diarrheal illness and gastrointestinal diseases. S. Typhimurium survives and replicates in phagocytic and non-phagocytic cells for acute or chronic infections. In these cells, S. Typhimurium resides within Salmonella-containing vacuoles (SCVs), in which the phosphate (Pi) concentration is low. S. Typhimurium senses low Pi and expresses virulence factors to modify host cells. However, the mechanism by which host cells reduce the Pi concentration in SCVs is not clear. In this study, we show that through the TLR4-MyD88-NF-κB signaling pathway, S. Typhimurium upregulates PIT1, which in turn transports Pi from SCVs into the cytosol and results in Pi starvation in SCVs. Immunofluorescence and western blotting analysis reveal that after the internalization of S. Typhimurium, PIT1 is located on SCV membranes. Silencing or overexpressing PIT1 inhibits or promotes Pi starvation, Salmonella pathogenicity island-2 (SPI-2) gene expression, and replication in SCVs. The S. Typhimurium ΔmsbB mutant or silenced TLR4-MyD88-NF-κB pathway suppresses the expression of the SPI-2 genes and promotes the fusion of SCVs with lysosomes. Our results illustrate that S. Typhimurium exploits the host innate immune responses as signals to promote intracellular replication, and they provide new insights for the development of broad-spectrum therapeutics to combat bacterial infections.
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Affiliation(s)
- Wen Yang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China; (W.Y.); (Y.F.); (J.Y.); (C.K.); (T.Y.); (H.S.)
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin 300457, China
| | - Yingxing Feng
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China; (W.Y.); (Y.F.); (J.Y.); (C.K.); (T.Y.); (H.S.)
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Jun Yan
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China; (W.Y.); (Y.F.); (J.Y.); (C.K.); (T.Y.); (H.S.)
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin 300457, China
| | - Chenbo Kang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China; (W.Y.); (Y.F.); (J.Y.); (C.K.); (T.Y.); (H.S.)
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin 300457, China
| | - Ting Yao
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China; (W.Y.); (Y.F.); (J.Y.); (C.K.); (T.Y.); (H.S.)
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin 300457, China
| | - Hongmin Sun
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China; (W.Y.); (Y.F.); (J.Y.); (C.K.); (T.Y.); (H.S.)
- TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin 300457, China
| | - Zhihui Cheng
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin 300071, China; (W.Y.); (Y.F.); (J.Y.); (C.K.); (T.Y.); (H.S.)
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
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2
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Su Y, Sun T, Gao J, Zhang C, Liu X, Bi C, Wang J, Shan A. Anti-Proteolytic Peptide R7I Protects the Intestinal Barrier and Alleviates Fatty Acid Malabsorption in Salmonella typhimurium-Infected Mice. Int J Mol Sci 2023; 24:16409. [PMID: 38003599 PMCID: PMC10670956 DOI: 10.3390/ijms242216409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 10/26/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
With a wide range of hosts, environmental adaptation, and antibiotic resistance, Salmonella typhimurium is one of the most common causes of food poisoning in the world. Infection with Salmonella typhimurium not only results in intestinal inflammation but also damages the intestinal barrier and interferes with the host's ability to absorb nutrients. It is imperative to find alternatives to antibiotics for eradicating bacteria, reducing intestinal damage, and reestablishing nutrient absorption, especially given that antibiotics are currently prohibited. This research aims to understand the protective role of anti-proteolytic peptide R7I on the gut in the setting of Salmonella typhimurium infection and its impact on nutritional absorption, maybe offering an alternative to antibiotics for bacterial killing. The findings demonstrated that R7I reduced the production of inflammatory factors, including IL-6, TNF-α, and L-1β in the jejunum and decreased the expression of genes like TLR4 and NF-κB in the jejunum (p < 0.05). R7I enhanced antioxidant capacity and preserved the antioxidant/pro-oxidant balance in the jejunum (p < 0.05). R7I also normalized intestinal shape and restored tight junction protein expression. Fatty acid binding protein 2 (FABP2) and fatty acid transport protein 4 (FATP4) expression in the jejunum was restored by R7I. In addition, serum-free fatty acids and lipid metabolites were significantly higher in the R7I group than in the control group (p < 0.05). Overall, the anti-enzyme peptide R7I maintained the healthy state of the intestine and alleviated the abnormal fatty acid absorption caused by bacterial infection.
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Affiliation(s)
| | | | | | | | | | | | - Jiajun Wang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (Y.S.); (T.S.); (J.G.); (C.Z.); (X.L.); (C.B.)
| | - Anshan Shan
- College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China; (Y.S.); (T.S.); (J.G.); (C.Z.); (X.L.); (C.B.)
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3
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Chandrasekhar H, Mohapatra G, Kajal K, Singh M, Walia K, Rana S, Kaur N, Sharma S, Tuli A, Das P, Srikanth CV. SifA SUMOylation governs Salmonella Typhimurium intracellular survival via modulation of lysosomal function. PLoS Pathog 2023; 19:e1011686. [PMID: 37773952 PMCID: PMC10566704 DOI: 10.1371/journal.ppat.1011686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 10/11/2023] [Accepted: 09/14/2023] [Indexed: 10/01/2023] Open
Abstract
One of the mechanisms shaping the pathophysiology during the infection of enteric pathogen Salmonella Typhimurium is host PTM machinery utilization by the pathogen encoded effectors. Salmonella Typhimurium (S. Tm) during infection in host cells thrives in a vacuolated compartment, Salmonella containing vacuole (SCV), which sequentially acquires host endosomal and lysosomal markers. Long tubular structures, called as Salmonella induced filaments (SIFs), are further generated by S. Tm, which are known to be required for SCV's nutrient acquisition, membrane maintenance and stability. A tightly coordinated interaction involving prominent effector SifA and various host adapters PLEKHM1, PLEKHM2 and Rab GTPases govern SCV integrity and SIF formation. Here, we report for the first time that the functional regulation of SifA is modulated by PTM SUMOylation at its 11th lysine. S. Tm expressing SUMOylation deficient lysine 11 mutants of SifA (SifAK11R) is defective in intracellular proliferation due to compromised SIF formation and enhanced lysosomal acidification. Furthermore, murine competitive index experiments reveal defective in vivo proliferation and weakened virulence of SifAK11R mutant. Concisely, our data reveal that SifAK11R mutant nearly behaves like a SifA knockout strain which impacts Rab9-MPR mediated lysosomal acidification pathway, the outcome of which culminates in reduced bacterial load in in vitro and in vivo infection model systems. Our results bring forth a novel pathogen-host crosstalk mechanism where the SUMOylation of effector SifA regulated S. Tm intracellular survival.
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Affiliation(s)
| | - Gayatree Mohapatra
- Systems Immunology Department, Weizmann Institute of Science, Rehovot, Israel
| | - Kirti Kajal
- Regional Centre for Biotechnology, Faridabad, India
| | - Mukesh Singh
- All India Institute of Medical Sciences (AIIMS), New Delhi, India
| | - Kshitiz Walia
- Institute of Microbial Technology, Chandigarh, India
| | - Sarika Rana
- Laboratory of Immunobiology, Universite´ Libre de Bruxelles, Gosselies, Belgium
| | - Navneet Kaur
- Department of Laboratory Medicine, Yale University, New Haven, Connecticut, United States of America
| | | | - Amit Tuli
- Institute of Microbial Technology, Chandigarh, India
| | - Prasenjit Das
- All India Institute of Medical Sciences (AIIMS), New Delhi, India
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4
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Chatterjee R, Chowdhury AR, Mukherjee D, Chakravortty D. From Eberthella typhi to Salmonella Typhi: The Fascinating Journey of the Virulence and Pathogenicity of Salmonella Typhi. ACS OMEGA 2023; 8:25674-25697. [PMID: 37521659 PMCID: PMC10373206 DOI: 10.1021/acsomega.3c02386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 06/30/2023] [Indexed: 08/01/2023]
Abstract
Salmonella Typhi (S. Typhi), the invasive typhoidal serovar of Salmonella enterica that causes typhoid fever in humans, is a severe threat to global health. It is one of the major causes of high morbidity and mortality in developing countries. According to recent WHO estimates, approximately 11-21 million typhoid fever illnesses occur annually worldwide, accounting for 0.12-0.16 million deaths. Salmonella infection can spread to healthy individuals by the consumption of contaminated food and water. Typhoid fever in humans sometimes is accompanied by several other critical extraintestinal complications related to the central nervous system, cardiovascular system, pulmonary system, and hepatobiliary system. Salmonella Pathogenicity Island-1 and Salmonella Pathogenicity Island-2 are the two genomic segments containing genes encoding virulent factors that regulate its invasion and systemic pathogenesis. This Review aims to shed light on a comparative analysis of the virulence and pathogenesis of the typhoidal and nontyphoidal serovars of S. enterica.
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Affiliation(s)
- Ritika Chatterjee
- Department
of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Atish Roy Chowdhury
- Department
of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Debapriya Mukherjee
- Department
of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Dipshikha Chakravortty
- Department
of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, Karnataka 560012, India
- Centre
for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, Karnataka 560012, India
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5
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Achi SC, Karimilangi S, Lie D, Sayed IM, Das S. The WxxxE proteins in microbial pathogenesis. Crit Rev Microbiol 2023; 49:197-213. [PMID: 35287539 PMCID: PMC9737147 DOI: 10.1080/1040841x.2022.2046546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 02/10/2022] [Accepted: 02/19/2022] [Indexed: 12/14/2022]
Abstract
Effector proteins secreted by pathogens modulate various host cellular processes and help in bacterial pathogenesis. Some of these proteins, injected by enteric pathogens via Type Three Secretion System (T3SS) were grouped together based on a conserved signature motif (WxxxE) present in them. The presence of WxxxE motif is not limited to effectors released by enteric pathogens or the T3SS but has been detected in non-enteric pathogens, plant pathogens and in association with Type II and Type IV secretion systems. WxxxE effectors are involved in actin organization, inflammation regulation, vacuole or tubule formation, endolysosomal signalling regulation, tight junction disruption, and apoptosis. The WxxxE sequence has also been identified in TIR [Toll/interleukin-1 (IL-1) receptor] domains of bacteria and host. In the present review, we have focussed on the established and predicted functions of WxxxE effectors secreted by several pathogens, including enteric, non-enteric, and plant pathogens.
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Affiliation(s)
| | - Sareh Karimilangi
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Dominique Lie
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Ibrahim M. Sayed
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Soumita Das
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
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6
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Takahashi Y, Abe H, Koayama K, Koseki S. Modeling the invasion of human small intestinal epithelial-like cells by Salmonella enterica Typhimurium and Listeria monocytogenes using Bayesian inference. Lett Appl Microbiol 2022; 75:388-395. [PMID: 35575530 DOI: 10.1111/lam.13738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/05/2022] [Accepted: 05/10/2022] [Indexed: 11/29/2022]
Abstract
In order to develop a mechanistic bacterial dose-response model, based on the concept of Key Events Dose-Response Framework (KEDRF), this study aimed to investigate the invasion of intestinal model cells (Caco-2) by Salmonella Typhimurium and Listeria monocytogenes and described the behavior of both pathogens as a mathematical model using Bayesian inference. Monolayer-cultured Caco-2 cells (approximately 105 cells) were co-cultured with various concentrations (103 - 107 CFU·ml-1 ) of S. Typhimurium and L. monocytogenes for up to 9 h to investigate the invasion of the pathogens into the Caco-2 cells. While an exposure of ≥ 103 CFU·ml-1 of S. Typhimurium initiated the invasion of Caco-2 cells within 3 h, much less exposure (102 CFU·ml-1 ) of L. monocytogenes was sufficient for invasion within the same period. Furthermore, while the maximum number of invading S. Typhimurium cells reached by approximately 103 CFU·cm-2 for 6 h exposure , the invading maximum numbers of L. monocytogenes cells increased by approximately 106 CFU·cm-2 for the same exposure period. The invasion kinetics of both the pathogens was successfully described as an asymptotic exponential mathematical model using Bayesian inference. The developed pathogen invasion model allowed the estimation of probability of S. Typhimurium and L. monocytogenes infection, based on the physiological natures of digestion process, which was comparable to the published dose-response relationship. The invasion models developed in the present study will play a key role in the development of an alternative pathogen dose-response models based on KEDRF concept.
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Affiliation(s)
- Yumeka Takahashi
- Graduate School of Agricultural Science, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan
| | - Hiroki Abe
- Graduate School of Agricultural Science, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan
| | - Kento Koayama
- Graduate School of Agricultural Science, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan
| | - Shigenobu Koseki
- Graduate School of Agricultural Science, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan
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7
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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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8
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Molecular determinants of peaceful coexistence versus invasiveness of non-Typhoidal Salmonella: Implications in long-term side-effects. Mol Aspects Med 2021; 81:100997. [PMID: 34311996 DOI: 10.1016/j.mam.2021.100997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 07/02/2021] [Accepted: 07/16/2021] [Indexed: 01/28/2023]
Abstract
The genus Salmonella represents a wide range of strains including Typhoidal and Non-Typhoidal Salmonella (NTS) isolates that exhibit illnesses of varied pathophysiologies. The more frequent NTS ensues a self-limiting enterocolitis with rare occasions of bacteremia or systemic infections. These self-limiting Salmonella strains are capable of subverting and dampening the host immune system to achieve a more prolonged survival inside the host system thus leading to chronic manifestations. Notably, emergence of new invasive NTS isolates known as invasive Non-Typhoidal Salmonella (iNTS) have worsened the disease burden significantly in some parts of the world. NTS strains adapt to attain persister phenotype intracellularly and cause relapsing infections. These chronic infections, in susceptible hosts, are also capable of causing diseases like IBS, IBD, reactive arthritis, gallbladder cancer and colorectal cancer. The present understanding of molecular mechanism of how these chronic infections are manifested is quite limited. The current work is an effort to review the prevailing knowledge emanating from a large volume of research focusing on various forms of NTS infections including those that cause localized, systemic and persistent disease. The review will further dwell into the understanding of how this pathogen contributes to the associated long term sequelae.
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9
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Röder J, Felgner P, Hensel M. Single-cell analyses reveal phosphate availability as critical factor for nutrition of Salmonella enterica within mammalian host cells. Cell Microbiol 2021; 23:e13374. [PMID: 34160116 DOI: 10.1111/cmi.13374] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 06/06/2021] [Accepted: 06/18/2021] [Indexed: 01/23/2023]
Abstract
Salmonella enterica serovar Typhimurium (STM) is an invasive, facultative intracellular pathogen and acquisition of nutrients from host cells is essential for survival and proliferation of intracellular STM. The nutritional environment of intracellular STM is only partially understood. We deploy bacteria harbouring reporter plasmids to interrogate the environmental cues acting on intracellular STM, and flow cytometry allows analyses on level of single STM. Phosphorus is a macro-element for cellular life, and in STM inorganic phosphate (Pi ), homeostasis is mediated by the two-component regulatory system PhoBR, resulting in expression of the high affinity phosphate transporter pstSCAB-phoU. Using fluorescent protein reporters, we investigated Pi availability for intracellular STM at single-cell level over time. We observed that Pi concentration in the Salmonella-containing vacuole (SCV) is limiting and activates the promoter of pstSCAB-phoU encoding a high affinity phosphate uptake system. Correlation between reporter activation by STM in defined media and in host cells indicates Pi concentration less 10 μM within the SCV. STM proliferating within the SCV experience increasing Pi limitations. Activity of the Salmonella pathogenicity island 2 (SPI2)-encoded type III secretion system (T3SS) is crucial for efficient intracellular proliferation, and SPI2-T3SS-mediated endosomal remodelling also reliefs Pi limitation. STM that are released from SCV to enter the cytosol of epithelial cells did not indicate Pi limitations. Addition of Pi to culture media of infected cells partially relieved Pi limitations in the SCV, as did inhibition of intracellular proliferation. We conclude that availability of Pi is critical for intracellular lifestyle of STM, and Pi acquisition is maintained by multiple mechanisms. Our work demonstrates the use of bacterial pathogens as sensitive single-cell reporters for their environment in host cell or host organisms. TAKE AWAY: Salmonella strains were engineered to report their intracellular niche and the availability of inorganic phosphate (Pi ) on level of single intracellular bacteria Within the Salmonella-containing vacuole (SCV), Pi is limited and limitation increases with bacterial proliferation Salmonella located in host cell cytosol are not limited in Pi availability Remodelling of the host cell endosomal system mediated by T3SS-2 reliefs Pi limitation in the SCV.
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Affiliation(s)
- Jennifer Röder
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Pascal Felgner
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.,CellNanOs-Center of Cellular Nanoanalytics, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
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10
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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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11
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Röder J, Felgner P, Hensel M. Comprehensive Single Cell Analyses of the Nutritional Environment of Intracellular Salmonella enterica. Front Cell Infect Microbiol 2021; 11:624650. [PMID: 33834004 PMCID: PMC8021861 DOI: 10.3389/fcimb.2021.624650] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/25/2021] [Indexed: 12/11/2022] Open
Abstract
The facultative intracellular pathogen Salmonella enterica Typhimurium (STM) resides in a specific membrane-bound compartment termed the Salmonella-containing vacuole (SCV). STM is able to obtain all nutrients required for rapid proliferation, although being separated from direct access to host cell metabolites. The formation of specific tubular membrane compartments, called Salmonella-induced filaments (SIFs) are known to provides bacterial nutrition by giving STM access to endocytosed material and enabling proliferation. Additionally, STM expresses a range of nutrient uptake system for growth in nutrient limited environments to overcome the nutrition depletion inside the host. By utilizing dual fluorescence reporters, we shed light on the nutritional environment of intracellular STM in various host cells and distinct intracellular niches. We showed that STM uses nutrients of the host cell and adapts uniquely to the different nutrient conditions. In addition, we provide further evidence for improved nutrient supply by SIF formation or presence in the cytosol of epithelial cells, and the correlation of nutrient supply to bacterial proliferation.
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Affiliation(s)
- Jennifer Röder
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Pascal Felgner
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs – Center of Cellular Nanoanalytics, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
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12
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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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13
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Kehl A, Göser V, Reuter T, Liss V, Franke M, John C, Richter CP, Deiwick J, Hensel M. A trafficome-wide RNAi screen reveals deployment of early and late secretory host proteins and the entire late endo-/lysosomal vesicle fusion machinery by intracellular Salmonella. PLoS Pathog 2020; 16:e1008220. [PMID: 32658937 PMCID: PMC7377517 DOI: 10.1371/journal.ppat.1008220] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 07/23/2020] [Accepted: 05/19/2020] [Indexed: 12/17/2022] Open
Abstract
The intracellular lifestyle of Salmonella enterica is characterized by the formation of a replication-permissive membrane-bound niche, the Salmonella-containing vacuole (SCV). As a further consequence of the massive remodeling of the host cell endosomal system, intracellular Salmonella establish a unique network of various Salmonella-induced tubules (SIT). The bacterial repertoire of effector proteins required for the establishment for one type of these SIT, the Salmonella-induced filaments (SIF), is rather well-defined. However, the corresponding host cell proteins are still poorly understood. To identify host factors required for the formation of SIF, we performed a sub-genomic RNAi screen. The analyses comprised high-resolution live cell imaging to score effects on SIF induction, dynamics and morphology. The hits of our functional RNAi screen comprise: i) The late endo-/lysosomal SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex, consisting of STX7, STX8, VTI1B, and VAMP7 or VAMP8, which is, in conjunction with RAB7 and the homotypic fusion and protein sorting (HOPS) tethering complex, a complete vesicle fusion machinery. ii) Novel interactions with the early secretory GTPases RAB1A and RAB1B, providing a potential link to coat protein complex I (COPI) vesicles and reinforcing recently identified ties to the endoplasmic reticulum. iii) New connections to the late secretory pathway and/or the recycling endosome via the GTPases RAB3A, RAB8A, and RAB8B and the SNAREs VAMP2, VAMP3, and VAMP4. iv) An unprecedented involvement of clathrin-coated structures. The resulting set of hits allowed us to characterize completely new host factor interactions, and to strengthen observations from several previous studies. The facultative intracellular pathogen Salmonella enterica serovar Typhimurium induces the reorganization of the endosomal system of mammalian host cells. This activity is dependent on translocated effector proteins of the pathogen. The host cell factors required for endosomal remodeling are only partially known. To identify such factors for the formation and dynamics of endosomal compartments in Salmonella-infected cells, we performed a live cell imaging-based RNAi screen to investigate the role of 496 mammalian proteins involved in cellular logistics. We identified that endosomal remodeling by intracellular Salmonella is dependent on host factors in the following functional classes: i) the late endo-/lysosomal SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex, ii) the early secretory pathway, represented by regulator GTPases RAB1A and RAB1B, iii) the late secretory pathway and/or recycling endosomes represented by GTPases RAB3A, RAB8A, RAB8B, and the SNAREs VAMP2, VAMP3, and VAMP4, and iv) clathrin-coated structures. The identification of these new host factors provides further evidence for the complex manipulation of host cell transport functions by intracellular Salmonella and should enable detailed follow-up studies on the mechanisms involved.
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Affiliation(s)
- Alexander Kehl
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
- Division of Biophysics, University of Osnabrück, Osnabrück, Germany
- * E-mail: (AK); (MH)
| | - Vera Göser
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Tatjana Reuter
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Viktoria Liss
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Maximilian Franke
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Christopher John
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
| | | | - Jörg Deiwick
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Division of Microbiology, University of Osnabrück, Osnabrück, Germany
- CellNanOs–Center for Cellular Nanoanalytics, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
- * E-mail: (AK); (MH)
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14
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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: 8] [Impact Index Per Article: 2.0] [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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15
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Reuter T, Vorwerk S, Liss V, Chao TC, Hensel M, Hansmeier N. Proteomic Analysis of Salmonella-modified Membranes Reveals Adaptations to Macrophage Hosts. Mol Cell Proteomics 2020; 19:900-912. [PMID: 32102972 PMCID: PMC7196581 DOI: 10.1074/mcp.ra119.001841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/24/2020] [Indexed: 01/19/2023] Open
Abstract
Systemic infection and proliferation of intracellular pathogens require the biogenesis of a growth-stimulating compartment. The gastrointestinal pathogen Salmonella enterica commonly forms highly dynamic and extensive tubular membrane compartments built from Salmonella-modified membranes (SMMs) in diverse host cells. Although the general mechanism involved in the formation of replication-permissive compartments of S. enterica is well researched, much less is known regarding specific adaptations to different host cell types. Using an affinity-based proteome approach, we explored the composition of SMMs in murine macrophages. The systematic characterization provides a broader landscape of host players to the maturation of Salmonella-containing compartments and reveals core host elements targeted by Salmonella in macrophages as well as epithelial cells. However, we also identified subtle host specific adaptations. Some of these observations, such as the differential involvement of the COPII system, Rab GTPases 2A, 8B, 11 and ER transport proteins Sec61 and Sec22B may explain cell line-dependent variations in the pathophysiology of Salmonella infections. In summary, our system-wide approach demonstrates a hitherto underappreciated impact of the host cell type in the formation of intracellular compartments by Salmonella.
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Affiliation(s)
- Tatjana Reuter
- CellNanOs - Center for Cellular Nanoanalytics Osnabrück, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Stephanie Vorwerk
- CellNanOs - Center for Cellular Nanoanalytics Osnabrück, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Viktoria Liss
- Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Tzu-Chiao Chao
- Institute of Environmental Change and Society, Department of Biology, University of Regina, Regina, Canada
| | - Michael Hensel
- Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany; CellNanOs - Center for Cellular Nanoanalytics Osnabrück, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.
| | - Nicole Hansmeier
- Department of Biology, Faculty of Science, Luther College at University of Regina, Regina, Canada.
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16
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Gulati A, Shukla R, Mukhopadhaya A. Salmonella Effector SteA Suppresses Proinflammatory Responses of the Host by Interfering With IκB Degradation. Front Immunol 2019; 10:2822. [PMID: 31921113 PMCID: PMC6914705 DOI: 10.3389/fimmu.2019.02822] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 11/15/2019] [Indexed: 11/17/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is known to cause its virulence by secreting various effector proteins directly into the host cytoplasm via two distinct type III secretion systems (T3SS-1 and T3SS-2). Generally, T3SS-1-delivered effectors help Salmonella Typhimurium in the early phases of infection including invasion and immune modulation of the host cells, whereas T3SS-2 effectors mainly help in the survival of Salmonella Typhimurium within the host cells including maintenance of Salmonella-containing vacuole, replication of the bacteria, and dissemination. Some of the effectors are secreted via both T3SS-1 and T3SS-2, suggesting their role in distinct phases of infection of host cells. SteA is such an effector that is secreted by both T3SS-1 and T3SS-2. It has been shown to control the membrane dynamics of the Salmonella-containing vacuole within the host cells in the late phases of infection. In this manuscript, toward characterizing the T3SS-1 function of SteA, we found that SteA suppresses inflammatory responses of the host by interfering with the nuclear factor kappa B pathway. Our initial observation showed that the mice infected with steA-deleted Salmonella Typhimurium (ΔsteA) died earlier compared to the wild-type bacteria due to heightened immune responses, which indicated that SteA might suppress immune responses. Furthermore, our study revealed that SteA suppresses immune responses in macrophages by interfering with the degradation of IκB, the inhibitor of nuclear factor kappa B. SteA suppresses the ubiquitination and hence degradation of IκB by acting on Cullin-1 of the Skp-1, Cullin-1, F-box (SCF)-E3 ligase complex. Our study revealed that SteA suppresses a key step necessary for E3 ligase activation, i.e., neddylation of Cullin-1 by interfering with dissociation of its inhibitor Cand-1.
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Affiliation(s)
- Aakanksha Gulati
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sahibzada Ajit Singh Nagar, India
| | - Rhythm Shukla
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sahibzada Ajit Singh Nagar, India
| | - Arunika Mukhopadhaya
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sahibzada Ajit Singh Nagar, India
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17
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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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18
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Castanheira S, García-Del Portillo F. Salmonella Populations inside Host Cells. Front Cell Infect Microbiol 2017; 7:432. [PMID: 29046870 PMCID: PMC5632677 DOI: 10.3389/fcimb.2017.00432] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 09/20/2017] [Indexed: 11/13/2022] Open
Abstract
Bacteria of the Salmonella genus cause diseases ranging from gastroenteritis to life-threatening typhoid fever and are among the most successful intracellular pathogens known. After the invasion of the eukaryotic cell, Salmonella exhibits contrasting lifestyles with different replication rates and subcellular locations. Although Salmonella hyper-replicates in the cytosol of certain host cell types, most invading bacteria remain within vacuoles in which the pathogen proliferates at moderate rates or persists in a dormant-like state. Remarkably, these cytosolic and intra-vacuolar intracellular lifestyles are not mutually exclusive and can co-exist in the same infected host cell. The mechanisms that direct the invading bacterium to follow the cytosolic or intra-vacuolar “pathway” remain poorly understood. In vitro studies show predominance of either the cytosolic or the intra-vacuolar population depending on the host cell type invaded by the pathogen. The host and pathogen factors controlling phagosomal membrane integrity and, as consequence, the egress into the cytosol, are intensively investigated. Other aspects of major interest are the host defenses that may affect differentially the cytosolic and intra-vacuolar populations and the strategies used by the pathogen to circumvent these attacks. Here, we summarize current knowledge about these Salmonella intracellular subpopulations and discuss how they emerge during the interaction of this pathogen with the eukaryotic cell.
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Affiliation(s)
- Sónia Castanheira
- Laboratory of Intracellular Bacterial Pathogens, Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Francisco García-Del Portillo
- Laboratory of Intracellular Bacterial Pathogens, Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
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19
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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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20
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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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21
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Raines SA, Hodgkinson MR, Dowle AA, Pryor PR. The Salmonella effector SseJ disrupts microtubule dynamics when ectopically expressed in normal rat kidney cells. PLoS One 2017; 12:e0172588. [PMID: 28235057 PMCID: PMC5325298 DOI: 10.1371/journal.pone.0172588] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 02/07/2017] [Indexed: 11/18/2022] Open
Abstract
Salmonella effector protein SseJ is secreted by Salmonella into the host cell cytoplasm where it can then modify host cell processes. Whilst host cell small GTPase RhoA has previously been shown to activate the acyl-transferase activity of SseJ we show here an un-described effect of SseJ protein production upon microtubule dynamism. SseJ prevents microtubule collapse and this is independent of SseJ's acyl-transferase activity. We speculate that the effects of SseJ on microtubules would be mediated via its known interactions with the small GTPases of the Rho family.
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Affiliation(s)
- Sally A. Raines
- Department of Biology, Wentworth Way, University of York, York, United Kingdom
| | | | - Adam A. Dowle
- Technology Facility, Department of Biology, Wentworth Way, University of York, York, United Kingdom
| | - Paul R. Pryor
- Department of Biology, Wentworth Way, University of York, York, United Kingdom
- Hull York Medical School, University of York, York, United Kingdom
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22
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Fozo EM, Rucks EA. The Making and Taking of Lipids: The Role of Bacterial Lipid Synthesis and the Harnessing of Host Lipids in Bacterial Pathogenesis. Adv Microb Physiol 2016; 69:51-155. [PMID: 27720012 DOI: 10.1016/bs.ampbs.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In order to survive environmental stressors, including those induced by growth in the human host, bacterial pathogens will adjust their membrane physiology accordingly. These physiological changes also include the use of host-derived lipids to alter their own membranes and feed central metabolic pathways. Within the host, the pathogen is exposed to many stressful stimuli. A resulting adaptation is for pathogens to scavenge the host environment for readily available lipid sources. The pathogen takes advantage of these host-derived lipids to increase or decrease the rigidity of their own membranes, to provide themselves with valuable precursors to feed central metabolic pathways, or to impact host signalling and processes. Within, we review the diverse mechanisms that both extracellular and intracellular pathogens employ to alter their own membranes as well as their use of host-derived lipids in membrane synthesis and modification, in order to increase survival and perpetuate disease within the human host. Furthermore, we discuss how pathogen employed mechanistic utilization of host-derived lipids allows for their persistence, survival and potentiation of disease. A more thorough understanding of all of these mechanisms will have direct consequences for the development of new therapeutics, and specifically, therapeutics that target pathogens, while preserving normal flora.
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Affiliation(s)
- E M Fozo
- University of Tennessee, Knoxville, TN, United States.
| | - E A Rucks
- Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States.
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23
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Salmonella Effectors SseF and SseG Interact with Mammalian Protein ACBD3 (GCP60) To Anchor Salmonella-Containing Vacuoles at the Golgi Network. mBio 2016; 7:mBio.00474-16. [PMID: 27406559 PMCID: PMC4958240 DOI: 10.1128/mbio.00474-16] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Following infection of mammalian cells, Salmonella enterica serovar Typhimurium (S. Typhimurium) replicates within membrane-bound compartments known as Salmonella-containing vacuoles (SCVs). The Salmonella pathogenicity island 2 type III secretion system (SPI-2 T3SS) translocates approximately 30 different effectors across the vacuolar membrane. SseF and SseG are two such effectors that are required for SCVs to localize close to the Golgi network in infected epithelial cells. In a yeast two-hybrid assay, SseG and an N-terminal variant of SseF interacted directly with mammalian ACBD3, a multifunctional cytosolic Golgi network-associated protein. Knockdown of ACBD3 by small interfering RNA (siRNA) reduced epithelial cell Golgi network association of wild-type bacteria, phenocopying the effect of null mutations of sseG or sseF. Binding of SseF to ACBD3 in infected cells required the presence of SseG. A single-amino-acid mutant of SseG and a double-amino-acid mutant of SseF were obtained that did not interact with ACBD3 in Saccharomyces cerevisiae. When either of these was produced together with the corresponding wild-type effector by Salmonella in infected cells, they enabled SCV-Golgi network association and interacted with ACBD3. However, these properties were lost and bacteria displayed an intracellular replication defect when cells were infected with Salmonella carrying both mutant genes. Knockdown of ACBD3 resulted in a replication defect of wild-type bacteria but did not further attenuate the growth defect of a ΔsseFG mutant strain. We propose a model in which interaction between SseF and SseG enables both proteins to bind ACBD3, thereby anchoring SCVs at the Golgi network and facilitating bacterial replication. Upon invasion of epithelial cells, the majority of vacuoles containing Salmonella enterica migrate to the perinuclear region-located Golgi network and remain in this region of the cell during the first few rounds of bacterial replication, forming a clustered microcolony of vacuoles. This process requires the action of SseF and SseG, two effector proteins that are translocated by the Salmonella SPI-2 type III secretion system. However, little is known about how they function. Here, we show that both proteins interact with the mammalian Golgi network-associated protein ACBD3. To our knowledge, the SseF-SseG-ACBD3 interaction is the first example of a tethering complex between a pathogen-containing vacuole and a host cell organelle.
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24
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Afonso-Grunz F. Putative alternative polyadenylation (APA) events in the early interaction of Salmonella enterica Typhimurium and human host cells. GENOMICS DATA 2015; 6:222-7. [PMID: 26697380 PMCID: PMC4664775 DOI: 10.1016/j.gdata.2015.10.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 10/01/2015] [Accepted: 10/02/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Fabian Afonso-Grunz
- Goethe University Frankfurt am Main, Institute for Molecular BioSciences, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.Goethe University Frankfurt am MainInstitute for Molecular BioSciencesMax-von-Laue-Str. 9Frankfurt am Main60438Germany.
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25
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Santos JC, Duchateau M, Fredlund J, Weiner A, Mallet A, Schmitt C, Matondo M, Hourdel V, Chamot-Rooke J, Enninga J. The COPII complex and lysosomal VAMP7 determine intracellular Salmonella localization and growth. Cell Microbiol 2015; 17:1699-720. [PMID: 26084942 DOI: 10.1111/cmi.12475] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/22/2015] [Accepted: 06/12/2015] [Indexed: 12/18/2022]
Abstract
Salmonella invades epithelial cells and survives within a membrane-bound compartment, the Salmonella-containing vacuole (SCV). We isolated and determined the host protein composition of the SCV at 30 min and 3 h of infection to identify and characterize novel regulators of intracellular bacterial localization and growth. Quantitation of the SCV protein content revealed 392 host proteins specifically enriched at SCVs, out of which 173 associated exclusively with early SCVs, 124 with maturing SCV and 95 proteins during both time-points. Vacuole interactions with endoplasmic reticulum-derived coat protein complex II vesicles modulate early steps of SCV maturation, promoting SCV rupture and bacterial hyper-replication within the host cytosol. On the other hand, SCV interactions with VAMP7-positive lysosome-like vesicles promote Salmonella-induced filament formation and bacterial growth within the late SCV. Our results reveal that the dynamic communication between the SCV and distinct host organelles affects both intracellular Salmonella localization and growth at successive steps of host cell invasion.
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Affiliation(s)
- José Carlos Santos
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France.,Graduate Program in Areas of Basic and Applied Biology (GABBA), University of Porto, Porto, Portugal
| | - Magalie Duchateau
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France
| | - Jennifer Fredlund
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
| | - Allon Weiner
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
| | - Adeline Mallet
- Plate-forme Microscopie Ultrastructurale, Institut Pasteur, Paris, France
| | - Christine Schmitt
- Plate-forme Microscopie Ultrastructurale, Institut Pasteur, Paris, France
| | - Mariette Matondo
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France
| | - Véronique Hourdel
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France
| | - Julia Chamot-Rooke
- Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, Paris, France.,CNRS UMR3528, Paris, France
| | - Jost Enninga
- Unit of Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
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26
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Abstract
Salmonellae invasion and intracellular replication within host cells result in a range of diseases, including gastroenteritis, bacteraemia, enteric fever and focal infections. In recent years, considerable progress has been made in our understanding of the molecular mechanisms that salmonellae use to alter host cell physiology; through the delivery of effector proteins with specific activities and through the modulation of defence and stress response pathways. In this Review, we summarize our current knowledge of the complex interplay between bacterial and host factors that leads to inflammation, disease and, in most cases, control of the infection by its animal hosts, with a particular focus on Salmonella enterica subsp. enterica serovar Typhimurium. We also highlight gaps in our knowledge of the contributions of salmonellae and the host to disease pathogenesis, and we suggest future avenues for further study.
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Affiliation(s)
- Doris L. LaRock
- Department of Microbiology, University of Washington, Seattle, WA 98195
| | - Anu Chaudhary
- Department of Microbiology, University of Washington, Seattle, WA 98195
| | - Samuel I. Miller
- Department of Microbiology, University of Washington, Seattle, WA 98195
- Department of Genome Sciences, University of Washington, Seattle, WA 98195
- Department of Immunology, University of Washington, Seattle, WA 98195
- Department of Medicine, University of Washington, Seattle, WA 98195
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Kolodziejek AM, Miller SI. Salmonella modulation of the phagosome membrane, role of SseJ. Cell Microbiol 2015; 17:333-41. [PMID: 25620407 DOI: 10.1111/cmi.12420] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 12/15/2022]
Abstract
Salmonellae have the ability to invade, persist and replicate within an intracellular phagosome termed the Salmonella-containing vacuole (SCV). Salmonellae alter lipid and protein content of the SCV membrane and manipulate cytoskeletal elements in contact with the SCV using the Salmonella pathogenicity island 1 (SPI-2) type III secretion system effectors. These modifications result in microtubular-based movement and morphological changes, which include endosomal tubulation of the SCV membrane. SseJ is a SPI-2 effector that localizes to the cytoplasmic face of the SCV and esterifies cholesterol through its glycerophospholipid : cholesterol acyltransferase activity. SseJ enzymatic activity as well as localization to the SCV are determined by binding to the small mammalian GTPase, RhoA. This review will focus on current knowledge about the role of SseJ in SCV membrane modification and will discuss how the hypothesis that a major role of SPI-2 effectors is to modify SCV protein and lipid content to promote bacterial intracellular survival.
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Vorwerk S, Krieger V, Deiwick J, Hensel M, Hansmeier N. Proteomes of host cell membranes modified by intracellular activities of Salmonella enterica. Mol Cell Proteomics 2014; 14:81-92. [PMID: 25348832 DOI: 10.1074/mcp.m114.041145] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Intracellular pathogens need to establish a growth-stimulating host niche for survival and replication. A unique feature of the gastrointestinal pathogen Salmonella enterica serovar Typhimurium is the creation of extensive membrane networks within its host. An understanding of the origin and function of these membranes is crucial for the development of new treatment strategies. However, the characterization of this compartment is very challenging, and only fragmentary knowledge of its composition and biogenesis exists. Here, we describe a new proteome-based approach to enrich and characterize Salmonella-modified membranes. Using a Salmonella mutant strain that does not form this unique membrane network as a reference, we identified a high-confidence set of host proteins associated with Salmonella-modified membranes. This comprehensive analysis allowed us to reconstruct the interactions of Salmonella with host membranes. For example, we noted that Salmonella redirects endoplasmic reticulum (ER) membrane trafficking to its intracellular niche, a finding that has not been described for Salmonella previously. Our system-wide approach therefore has the potential to rapidly close gaps in our knowledge of the infection process of intracellular pathogens and demonstrates a hitherto unrecognized complexity in the formation of Salmonella host niches.
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Affiliation(s)
- Stephanie Vorwerk
- From the ‡Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Viktoria Krieger
- From the ‡Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Jörg Deiwick
- From the ‡Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Michael Hensel
- From the ‡Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Nicole Hansmeier
- From the ‡Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
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Pareja MEM, Colombo MI. Autophagic clearance of bacterial pathogens: molecular recognition of intracellular microorganisms. Front Cell Infect Microbiol 2013; 3:54. [PMID: 24137567 PMCID: PMC3786225 DOI: 10.3389/fcimb.2013.00054] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/02/2013] [Indexed: 01/01/2023] Open
Abstract
Autophagy is involved in several physiological and pathological processes. One of the key roles of the autophagic pathway is to participate in the first line of defense against the invasion of pathogens, as part of the innate immune response. Targeting of intracellular bacteria by the autophagic machinery, either in the cytoplasm or within vacuolar compartments, helps to control bacterial proliferation in the host cell, controlling also the spreading of the infection. In this review we will describe the means used by diverse bacterial pathogens to survive intracellularly and how they are recognized by the autophagic molecular machinery, as well as the mechanisms used to avoid autophagic clearance.
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Affiliation(s)
- Maria Eugenia Mansilla Pareja
- Laboratorio de Biología Celular y Molecular, Facultad de Ciencias Médicas, Instituto de Histología y Embriología-CONICET, Universidad Nacional de Cuyo Mendoza, Argentina
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Kidwai AS, Mushamiri I, Niemann GS, Brown RN, Adkins JN, Heffron F. Diverse secreted effectors are required for Salmonella persistence in a mouse infection model. PLoS One 2013; 8:e70753. [PMID: 23950998 PMCID: PMC3741292 DOI: 10.1371/journal.pone.0070753] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 06/26/2013] [Indexed: 01/08/2023] Open
Abstract
Salmonella enterica serovar Typhimurium causes typhoid-like disease in mice and is a model of typhoid fever in humans. One of the hallmarks of typhoid is persistence, the ability of the bacteria to survive in the host weeks after infection. Virulence factors called effectors facilitate this process by direct transfer to the cytoplasm of infected cells thereby subverting cellular processes. Secretion of effectors to the cell cytoplasm takes place through multiple routes, including two separate type III secretion (T3SS) apparati as well as outer membrane vesicles. The two T3SS are encoded on separate pathogenicity islands, SPI-1 and -2, with SPI-1 more strongly associated with the intestinal phase of infection, and SPI-2 with the systemic phase. Both T3SS are required for persistence, but the effectors required have not been systematically evaluated. In this study, mutations in 48 described effectors were tested for persistence. We replaced each effector with a specific DNA barcode sequence by allelic exchange and co-infected with a wild-type reference to calculate the ratio of wild-type parent to mutant at different times after infection. The competitive index (CI) was determined by quantitative PCR in which primers that correspond to the barcode were used for amplification. Mutations in all but seven effectors reduced persistence demonstrating that most effectors were required. One exception was CigR, a recently discovered effector that is widely conserved throughout enteric bacteria. Deletion of cigR increased lethality, suggesting that it may be an anti-virulence factor. The fact that almost all Salmonella effectors are required for persistence argues against redundant functions. This is different from effector repertoires in other intracellular pathogens such as Legionella.
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Affiliation(s)
- Afshan S. Kidwai
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Ivy Mushamiri
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - George S. Niemann
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Roslyn N. Brown
- Center for Bioproducts and Bioenergy, Washington State University, Richland, Washington, United States of America
| | - Joshua N. Adkins
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Fred Heffron
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
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The bimodal lifestyle of intracellular Salmonella in epithelial cells: replication in the cytosol obscures defects in vacuolar replication. PLoS One 2012; 7:e38732. [PMID: 22719929 PMCID: PMC3374820 DOI: 10.1371/journal.pone.0038732] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 05/10/2012] [Indexed: 11/29/2022] Open
Abstract
Salmonella enterica serovar Typhimurium invades and proliferates within epithelial cells. Intracellular bacteria replicate within a membrane bound vacuole known as the Salmonella containing vacuole. However, this bacterium can also replicate efficiently in the cytosol of epithelial cells and net intracellular growth is a product of both vacuolar and cytosolic replication. Here we have used semi-quantitative single-cell analyses to investigate the contribution of each of these replicative niches to intracellular proliferation in cultured epithelial cells. We show that cytosolic replication can account for the majority of net replication even though it occurs in less than 20% of infected cells. Consequently, assays for net growth in a population of infected cells, for example by recovery of colony forming units, are not good indicators of vacuolar proliferation. We also show that the Salmonella Type III Secretion System 2, which is required for SCV biogenesis, is not required for cytosolic replication. Altogether this study illustrates the value of single cell analyses when studying intracellular pathogens.
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van der Heijden J, Finlay BB. Type III effector-mediated processes in Salmonella infection. Future Microbiol 2012; 7:685-703. [DOI: 10.2217/fmb.12.49] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Salmonella is one of the most successful bacterial pathogens that infect humans in both developed and developing countries. In order to cause infection, Salmonella uses type III secretion systems to inject bacterial effector proteins into host cells. In the age of antibiotic resistance, researchers have been looking for new strategies to reduce Salmonella infection. To understand infection and to analyze type III secretion as a potential therapeutic target, research has focused on identification of effectors, characterization of effector functions and how they contribute to disease. Many effector-mediated processes have been identified that contribute to infection but thus far no specific treatment has been found. In this perspective we discuss our current understanding of effector-mediated processes and discuss new techniques and approaches that may help us to find a solution to this worldwide problem.
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Affiliation(s)
- Joris van der Heijden
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, Canada
| | - B Brett Finlay
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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Kaniuk NA, Canadien V, Bagshaw RD, Bakowski M, Braun V, Landekic M, Mitra S, Huang J, Heo WD, Meyer T, Pelletier L, Andrews-Polymenis H, McClelland M, Pawson T, Grinstein S, Brumell JH. Salmonella exploits Arl8B-directed kinesin activity to promote endosome tubulation and cell-to-cell transfer. Cell Microbiol 2011; 13:1812-23. [PMID: 21824248 DOI: 10.1111/j.1462-5822.2011.01663.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The facultative intracellular pathogen Salmonella enterica serovar Typhimurium establishes a replicative niche, the Salmonella-containing vacuole (SCV), in host cells. Here we demonstrate that these bacteria exploit the function of Arl8B, an Arf family GTPase, during infection. Following infection, Arl8B localized to SCVs and to tubulated endosomes that extended along microtubules in the host cell cytoplasm. Arl8B(+) tubules partially colocalized with LAMP1 and SCAMP3. Formation of LAMP1(+) tubules (the Salmonella-induced filaments phenotype; SIFs) required Arl8B expression. SIFs formation is known to require the activity of kinesin-1. Here we find that Arl8B is required for kinesin-1 recruitment to SCVs. We have previously shown that SCVs undergo centrifugal movement to the cell periphery at 24 h post infection and undergo cell-to-cell transfer to infect neighbouring cells, and that both phenotypes require kinesin-1 activity. Here we demonstrate that Arl8B is required for migration of the SCV to the cell periphery 24 h after infection and for cell-to-cell transfer of bacteria to neighbouring cells. These results reveal a novel host factor co-opted by S. Typhimurium to manipulate the host endocytic pathway and to promote the spread of infection within a host.
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Affiliation(s)
- Natalia A Kaniuk
- Cell Biology Program, Hospital for Sick Children, Toronto, ON, Canada
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da Silva CV, Cruz L, Araújo NDS, Angeloni MB, Fonseca BB, Gomes ADO, Carvalho FDR, Gonçalves ALR, Barbosa BDF. A glance at Listeria and Salmonella cell invasion: different strategies to promote host actin polymerization. Int J Med Microbiol 2011; 302:19-32. [PMID: 21783413 DOI: 10.1016/j.ijmm.2011.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 05/12/2011] [Accepted: 05/16/2011] [Indexed: 12/18/2022] Open
Abstract
The facultative intracellular bacterial pathogens Listeria monocytogenes and Salmonella enterica have evolved multiple strategies to invade a large panel of mammalian cells. These pathogens use the host cell actin system for invasion and became a paradigm for the study of host-pathogen interactions and bacterial adaptation to mammalian hosts. The key signaling component that these pathogens use to orchestrate actin remodeling is the Arp2/3 complex, which is related to polymerization of actin filaments. These bacterial pathogens are able to trigger distinct invasion mechanisms. On the one hand, L. monocytogenes invade a host cell in a way dependent on the specific interactions between bacterial and host cell proteins, which in turn activate the host cell actin polymerizing machinery that culminates with bacterial internalization. Also, Listeria escapes from the newly formed parasitophorous vacuole and moves among adjacent cells by triggering actin polymerization. On the other hand, Salmonella invades a host cell by delivering into the cytoplasm virulence factors which directly interact with host regulators of actin polymerization which leads to bacterial uptake. Moreover, Salmonella avoids vacuole lyses and modulates the early and late endosomal markers presented in the vacuole membrane. This mini-review focuses on the different pathways that L. monocytogenes and S. enterica activate to modulate the actin cytoskeleton in order to invade, to form the parasitophorous vacuole, and to migrate inside host cells.
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Affiliation(s)
- Claudio Vieira da Silva
- Programa de Pós-Graduação em Imunologia e Parasitologia Aplicadas, Universidade Federal de Uberlândia, Minas Gerais, Brazil.
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Abstract
Bacterial pathogens interact with host membranes to trigger a wide range of cellular processes during the course of infection. These processes include alterations to the dynamics between the plasma membrane and the actin cytoskeleton, and subversion of the membrane-associated pathways involved in vesicle trafficking. Such changes facilitate the entry and replication of the pathogen, and prevent its phagocytosis and degradation. In this Review, we describe the manipulation of host membranes by numerous bacterial effectors that target phosphoinositide metabolism, GTPase signalling and autophagy.
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Hallstrom K, McCormick BA. Salmonella Interaction with and Passage through the Intestinal Mucosa: Through the Lens of the Organism. Front Microbiol 2011; 2:88. [PMID: 21747800 PMCID: PMC3128981 DOI: 10.3389/fmicb.2011.00088] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 04/13/2011] [Indexed: 01/13/2023] Open
Abstract
Salmonella enterica serotypes are invasive enteric pathogens spread through fecal contamination of food and water sources, and represent a constant public health threat around the world. The symptoms associated with salmonellosis and typhoid disease are largely due to the host response to invading Salmonella, and to the mechanisms these bacteria employ to survive in the presence of, and invade through the intestinal mucosal epithelia. Surmounting this barrier is required for survival within the host, as well as for further dissemination throughout the body, and subsequent systemic disease. In this review, we highlight some of the major hurdles Salmonella must overcome upon encountering the intestinal mucosal epithelial barrier, and examine how these bacteria surmount and exploit host defense mechanisms.
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Affiliation(s)
- Kelly Hallstrom
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School Worcester, MA, USA
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Salmonella-induced tubular networks. Trends Microbiol 2011; 19:268-77. [PMID: 21353564 DOI: 10.1016/j.tim.2011.01.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 01/12/2011] [Accepted: 01/20/2011] [Indexed: 12/26/2022]
Abstract
Salmonella virulence relies on its capacity to replicate inside various cell types in a membrane-bound compartment, the Salmonella-containing vacuole (SCV). A unique feature of Salmonella-infected cells is the presence of tubular structures originating from and connected to the SCV, which often extend throughout the cell cytoplasm. These tubules include the well-studied Salmonella-induced filaments (SIFs), enriched in lysosomal membrane proteins. However, recent studies revealed that the Salmonella-induced tubular network is more extensive than previously thought and includes three types of tubules distinct from SIFs: sorting nexin tubules, Salmonella-induced secretory carrier membrane protein 3 (SCAMP3) tubules and lysosome-associated membrane protein 1 (LAMP1)-negative tubules. In this review, we examine the molecular mechanisms involved in the formation of Salmonella-induced tubular networks and discuss the importance of the tubules for Salmonella virulence and establishment of a Salmonella intracellular replicative niche.
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Trombert AN, Berrocal L, Fuentes JA, Mora GC. S. Typhimurium sseJ gene decreases the S. Typhi cytotoxicity toward cultured epithelial cells. BMC Microbiol 2010; 10:312. [PMID: 21138562 PMCID: PMC3004891 DOI: 10.1186/1471-2180-10-312] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 12/07/2010] [Indexed: 11/25/2022] Open
Abstract
Background Salmonella enterica serovar Typhi and Typhimurium are closely related serovars as indicated by >96% DNA sequence identity between shared genes. Nevertheless, S. Typhi is a strictly human-specific pathogen causing a systemic disease, typhoid fever. In contrast, S. Typhimurium is a broad host range pathogen causing only a self-limited gastroenteritis in immunocompetent humans. We hypothesize that these differences have arisen because some genes are unique to each serovar either gained by horizontal gene transfer or by the loss of gene activity due to mutation, such as pseudogenes. S. Typhi has 5% of genes as pseudogenes, much more than S. Typhimurium which contains 1%. As a consequence, S. Typhi lacks several protein effectors implicated in invasion, proliferation and/or translocation by the type III secretion system that are fully functional proteins in S. Typhimurium. SseJ, one of these effectors, corresponds to an acyltransferase/lipase that participates in SCV biogenesis in human epithelial cell lines and is needed for full virulence of S. Typhimurium. In S. Typhi, sseJ is a pseudogene. Therefore, we suggest that sseJ inactivation in S. Typhi has an important role in the development of the systemic infection. Results We investigated whether the S. Typhi trans-complemented with the functional sseJ gene from S. Typhimurium (STM) affects the cytotoxicity toward cultured cell lines. It was found that S. Typhi harbouring sseJSTM presents a similar cytotoxicity level and intracellular retention/proliferation of cultured epithelial cells (HT-29 or HEp-2) as wild type S. Typhimurium. These phenotypes are significantly different from wild type S. Typhi Conclusions Based on our results we conclude that the mutation that inactivate the sseJ gene in S. Typhi resulted in evident changes in the behaviour of bacteria in contact with eukaryotic cells, plausibly contributing to the S. Typhi adaptation to the systemic infection in humans.
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Affiliation(s)
- A Nicole Trombert
- Laboratorio de Microbiologia, Facultad de Ciencias Biologicas y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
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Bobard A, Mellouk N, Enninga J. Spotting the right location- imaging approaches to resolve the intracellular localization of invasive pathogens. Biochim Biophys Acta Gen Subj 2010; 1810:297-307. [PMID: 21029766 DOI: 10.1016/j.bbagen.2010.10.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 10/16/2010] [Accepted: 10/18/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND A common strategy of microbial pathogens is to invade host cells during infection. The invading microbes explore different intracellular compartments to find their preferred niche. SCOPE OF REVIEW Imaging has been instrumental to unravel paradigms of pathogen entry, to identify their exact intracellular location, and to understand the underlying mechanisms for the formation of pathogen-containing niches. Here, we provide an overview of imaging techniques that have been applied to monitor the intracellular lifestyle of pathogens, focusing mainly on bacteria that either remain in vacuolar-bound compartments or rupture the endocytic vacuole to escape into the host's cellular cytoplasm. MAJOR CONCLUSIONS We will depict common molecular and cellular paradigms that are preferentially exploited by pathogens. A combination of electron microscopy, fluorescence microscopy, and time-lapse microscopy has been the driving force to reveal underlying cell biological processes. Furthermore, the development of highly sensitive and specific fluorescent sensor molecules has allowed for the identification of functional aspects of niche formation by intracellular pathogens. GENERAL SIGNIFICANCE Currently, we are beginning to understand the sophistication of the invasion strategies used by bacterial pathogens during the infection process- innovative imaging has been a key ingredient for this. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine.
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Affiliation(s)
- Alexandre Bobard
- Institut Pasteur, Groupe "Dynamique des Interactions Hôte-Pathogène, Paris, France
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Bakowski MA, Braun V, Lam GY, Yeung T, Heo WD, Meyer T, Finlay BB, Grinstein S, Brumell JH. The phosphoinositide phosphatase SopB manipulates membrane surface charge and trafficking of the Salmonella-containing vacuole. Cell Host Microbe 2010; 7:453-62. [PMID: 20542249 DOI: 10.1016/j.chom.2010.05.011] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 03/23/2010] [Accepted: 04/26/2010] [Indexed: 11/17/2022]
Abstract
Shifts in electrostatic surface charge of membranes have recently been highlighted as a significant factor contributing to protein targeting to the plasma membrane and nascent phagosomes. Intracellular, vacuole-adapted pathogens may also regulate surface charge of their vacuoles to establish a replicative niche. Since Salmonella enterica serovar Typhimurium controls trafficking of the Salmonella-containing vacuole (SCV) and inhibits its fusion with lysosomes, we investigated the contribution of surface charge to this process. Using recently developed fluorescent biosensors, we show that the bacterial phosphoinositide phosphatase SopB controls membrane surface charge of nascent SCVs by reducing levels of negatively charged lipids phosphatidylinositol-4,5-bisphosphate and phosphatidylserine. This SopB activity results in dissociation of a number of host-cell endocytic trafficking proteins from this compartment and inhibits SCV-lysosome fusion. Moreover, inducible reduction of negative charge rescues DeltasopB bacteria-containing SCVs from fusion with lysosomes. These results reveal a membrane-charge-based mechanism used by S. Typhimurium to control SCV maturation.
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Affiliation(s)
- Malina A Bakowski
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
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Schroeder N, Henry T, de Chastellier C, Zhao W, Guilhon AA, Gorvel JP, Méresse S. The virulence protein SopD2 regulates membrane dynamics of Salmonella-containing vacuoles. PLoS Pathog 2010; 6:e1001002. [PMID: 20664790 PMCID: PMC2904799 DOI: 10.1371/journal.ppat.1001002] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 06/16/2010] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is a Gram-negative bacterial pathogen causing gastroenteritis in humans and a systemic typhoid-like illness in mice. The capacity of Salmonella to cause diseases relies on the establishment of its intracellular replication niche, a membrane-bound compartment named the Salmonella-containing vacuole (SCV). This requires the translocation of bacterial effector proteins into the host cell by type three secretion systems. Among these effectors, SifA is required for the SCV stability, the formation of Salmonella-induced filaments (SIFs) and plays an important role in the virulence of Salmonella. Here we show that the effector SopD2 is responsible for the SCV instability that triggers the cytoplasmic release of a sifA− mutant. Deletion of sopD2 also rescued intra-macrophagic replication and increased virulence of sifA− mutants in mice. Membrane tubular structures that extend from the SCV are the hallmark of Salmonella-infected cells. Until now, these unique structures have not been observed in the absence of SifA. The deletion of sopD2 in a sifA− mutant strain re-established membrane trafficking from the SCV and led to the formation of new membrane tubular structures, the formation of which is dependent on other Salmonella effector(s). Taken together, our data demonstrate that SopD2 inhibits the vesicular transport and the formation of tubules that extend outward from the SCV and thereby contributes to the sifA− associated phenotypes. These results also highlight the antagonistic roles played by SopD2 and SifA in the membrane dynamics of the vacuole, and the complex actions of SopD2, SifA, PipB2 and other unidentified effector(s) in the biogenesis and maintenance of the Salmonella replicative niche. Salmonella typhimurium is a bacterial pathogen that causes diseases ranging from gastroenteritis to typhoid fever. This bacterium survives inside eukaryotic cells within a membrane-bound compartment, namely the Salmonella-containing vacuole. Salmonella injects proteins, named effectors, into the infected cell. These effectors change the biology of the infected cell and collectively support Salmonella replication and virulence. The effector SifA plays a key role in the bacterial vacuole stability and in the formation of membrane tubules that extend from the vacuole. Absence of SifA leads to the disruption of the vacuolar membrane and, therefore to the release of bacteria in the cytosolic compartment. Consequently, this mutant presents significant replication and virulence defects. Here, we show that an additional Salmonella effector, SopD2, is responsible for the membrane instability of the sifA− vacuole. In addition, we demonstrate that SopD2 acts as an inhibitor of vesicle transport from the vacuole and that it down-modulates the formation of tubular structures. These findings describe a role for SopD2 as an antagonist of SifA in terms of vacuolar membrane dynamics.
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Affiliation(s)
- Nina Schroeder
- Centre d'Immunologie de Marseille-Luminy, CNRS UMR 6102, INSERM U631, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
| | - Thomas Henry
- Centre d'Immunologie de Marseille-Luminy, CNRS UMR 6102, INSERM U631, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
| | - Chantal de Chastellier
- Centre d'Immunologie de Marseille-Luminy, CNRS UMR 6102, INSERM U631, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
| | - Weidong Zhao
- Centre d'Immunologie de Marseille-Luminy, CNRS UMR 6102, INSERM U631, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
| | - Aude-Agnès Guilhon
- Centre d'Immunologie de Marseille-Luminy, CNRS UMR 6102, INSERM U631, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
| | - Jean-Pierre Gorvel
- Centre d'Immunologie de Marseille-Luminy, CNRS UMR 6102, INSERM U631, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
| | - Stéphane Méresse
- Centre d'Immunologie de Marseille-Luminy, CNRS UMR 6102, INSERM U631, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
- * E-mail:
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Braun V, Wong A, Landekic M, Hong WJ, Grinstein S, Brumell JH. Sorting nexin 3 (SNX3) is a component of a tubular endosomal network induced by Salmonella and involved in maturation of the Salmonella-containing vacuole. Cell Microbiol 2010; 12:1352-67. [PMID: 20482551 DOI: 10.1111/j.1462-5822.2010.01476.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Salmonella enterica serovar Typhimurium is an intracellular pathogen that grows within a modified endomembrane compartment, the Salmonella-containing vacuole (SCV). Maturation of nascent SCVs involves the recruitment of early endosome markers and the remodelling of phosphoinositides at the membrane of the vacuole, in particular the production of phosphatidylinositol 3-phosphate [PI(3)P]. Sorting nexins (SNXs) are a family of proteins characterized by the presence of a phox homology (PX) domain that binds to phosphoinositides and are involved in intracellular trafficking in eukaryotic cells. We therefore studied whether sorting nexins, particularly sorting nexin 3 (SNX3), play a role in Salmonella infection. We found that SNX3 transiently localized to SCVs at early times post invasion (10 min) and presented a striking tubulation phenotype in the vicinity of SCVs at later times (30-60 min). The bacterial effector SopB, which is known to promote PI(3)P production on SCVs, was required for the formation of SNX3 tubules. In addition, RAB5 was also required for the formation of SNX3 tubules. Depletion of SNX3 by siRNA impaired RAB7 and LAMP1 recruitment to the SCV. Moreover, the formation of Salmonella-induced filaments (Sifs) was altered by SNX3 knock-down. Therefore, SNX3 plays a significant role in regulating the maturation of SCVs.
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Affiliation(s)
- Virginie Braun
- Cell Biology Program, Hospital for Sick Children, Toronto, ON, Canada M5G1X8
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Abstract
The mammalian innate immune response provides a barrier against invading pathogens. Innate immune mechanisms are used by the host to respond to a range of bacterial pathogens in an acute and conserved fashion. Host cells express pattern recognition receptors that sense pathogen-associated molecular patterns. After detection, an arsenal of antimicrobial mechanisms is deployed to kill bacteria in infected cells. Innate immunity also stimulates antigen-specific responses mediated by the adaptive immune system. In response, pathogens manipulate host defence mechanisms to survive and eventually replicate. This Review focuses on the control of host innate immune responses by pathogenic intracellular bacteria.
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Lapaquette P, Glasser AL, Huett A, Xavier RJ, Darfeuille-Michaud A. Crohn's disease-associated adherent-invasive E. coli are selectively favoured by impaired autophagy to replicate intracellularly. Cell Microbiol 2009; 12:99-113. [PMID: 19747213 DOI: 10.1111/j.1462-5822.2009.01381.x] [Citation(s) in RCA: 236] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ileal lesions in Crohn's disease (CD) patients are colonized by pathogenic adherent-invasive Escherichia coli (AIEC) able to invade and to replicate within intestinal epithelial cells. Recent genome-wide association studies have highlighted the autophagy pathway as being associated with CD risk. In the present study we investigated whether defects in autophagy enhance replication of commensal and pathogenic Escherichia coli and CD-associated AIEC. We show that functional autophagy limits intracellular AIEC replication and that a subpopulation of the intracellular bacteria is located within LC3-positive autophagosomes. In IRGM and ATG16L1 deficient cells intracellular AIEC LF82 bacteria have enhanced replication. Surprisingly autophagy deficiency did not interfere with the ability of intracellular bacteria to survive and/or replicate for any other E. coli strains tested, including non-pathogenic, environmental, commensal, or pathogenic strains involved in gastro enteritis. Together these findings demonstrate a central role for autophagy restraining Adherent-Invasive E. coli strains associated with ileal CD. AIEC infection in patients with polymorphisms in autophagy genes may have a significant impact on the outcome of intestinal inflammation.
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Affiliation(s)
- Pierre Lapaquette
- Univ Clermont, Pathogénie Bactérienne Intestinale, USC-INRA, Clermont-Ferrand, France
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Lapaquette P, Glasser AL, Huett A, Xavier RJ, Darfeuille-Michaud A. Crohn's disease-associated adherent-invasive E. coli are selectively favoured by impaired autophagy to replicate intracellularly. Cell Microbiol 2009. [PMID: 19747213 DOI: 10.1111/j.1462-5822.2009.01381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ileal lesions in Crohn's disease (CD) patients are colonized by pathogenic adherent-invasive Escherichia coli (AIEC) able to invade and to replicate within intestinal epithelial cells. Recent genome-wide association studies have highlighted the autophagy pathway as being associated with CD risk. In the present study we investigated whether defects in autophagy enhance replication of commensal and pathogenic Escherichia coli and CD-associated AIEC. We show that functional autophagy limits intracellular AIEC replication and that a subpopulation of the intracellular bacteria is located within LC3-positive autophagosomes. In IRGM and ATG16L1 deficient cells intracellular AIEC LF82 bacteria have enhanced replication. Surprisingly autophagy deficiency did not interfere with the ability of intracellular bacteria to survive and/or replicate for any other E. coli strains tested, including non-pathogenic, environmental, commensal, or pathogenic strains involved in gastro enteritis. Together these findings demonstrate a central role for autophagy restraining Adherent-Invasive E. coli strains associated with ileal CD. AIEC infection in patients with polymorphisms in autophagy genes may have a significant impact on the outcome of intestinal inflammation.
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Affiliation(s)
- Pierre Lapaquette
- Univ Clermont, Pathogénie Bactérienne Intestinale, USC-INRA, Clermont-Ferrand, France
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Abstract
The endocytosis pathway controls multiple cellular and physiological events. The lysosome is the destination of newly synthesized lysosomal hydrolytic enzymes. Internalized molecules or particles are delivered to the lysosome for degradation through sequential transport along the endocytic pathway. The endocytic pathway is also emerging as a signalling platform, in addition to the well-known role of the plasma membrane for signalling. Rab7 is a late endosome-/lysosome-associated small GTPase, perhaps the only lysosomal Rab protein identified to date. Rab7 plays critical roles in the endocytic processes. Through interaction with its partners (including upstream regulators and downstream effectors), Rab7 participates in multiple regulation mechanisms in endosomal sorting, biogenesis of lysosome [or LRO (lysosome-related organelle)] and phagocytosis. These processes are closely related to substrates degradation, antigen presentation, cell signalling, cell survival and microbial pathogen infection. Consistently, mutations or dysfunctions of Rab7 result in traffic disorders, which cause various diseases, such as neuropathy, cancer and lipid metabolism disease. Rab7 also plays important roles in microbial pathogen infection and survival, as well as in participating in the life cycle of viruses. Here, we give a brief review on the central role of Rab7 in endosomal traffic and summarize the studies focusing on the participation of Rab7 in disease pathogenesis. The underlying mechanism governed by Rab7 and its partners will also be discussed.
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Structural insights into host GTPase isoform selection by a family of bacterial GEF mimics. Nat Struct Mol Biol 2009; 16:853-60. [PMID: 19620963 DOI: 10.1038/nsmb.1647] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 06/29/2009] [Indexed: 01/04/2023]
Abstract
The Escherichia coli type III effector Map belongs to a large family of bacterial virulence factors that activate host Rho GTPase signaling pathways through an unknown molecular mechanism. Here we report direct evidence that Map functions as a potent and selective guanine-nucleotide exchange factor (GEF) for Cdc42. The 2.3-A structure of the Map-Cdc42 complex revealed that Map mimics the GEF strategy of the mammalian Dbl family but has a three-dimensional architecture that is nearly identical to the bacterial GEF Salmonella spp. SopE. A comparative analysis between human and bacterial GEFs revealed a previously uncharacterized pairing mechanism between Map and the variable beta2-3 interswitch region of Cdc42. We propose a GTPase selection model that is experimentally validated by the preferential activation Rac1 and RhoA by the Shigella spp. effectors IpgB1 and IpgB2, respectively. These results significantly expand the repertoire of bacterial GEF mimics and unify a GEF selection mechanism for host GTPase substrates.
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Mota LJ, Ramsden AE, Liu M, Castle JD, Holden DW. SCAMP3 is a component of the Salmonella-induced tubular network and reveals an interaction between bacterial effectors and post-Golgi trafficking. Cell Microbiol 2009; 11:1236-53. [PMID: 19438519 PMCID: PMC2730479 DOI: 10.1111/j.1462-5822.2009.01329.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Salmonella enterica are facultative intracellular bacterial pathogens that proliferate within host cells in a membrane-bounded compartment, the Salmonella-containing vacuole (SCV). Intracellular replication of Salmonella is mediated by bacterial effectors translocated on to the cytoplasmic face of the SCV membrane by a type III secretion system. Some of these effectors manipulate the host endocytic pathway, resulting in the formation in epithelial cells of tubules enriched in late endosomal markers, known as Salmonella-induced filaments (SIFs). However, much less is known about possible interference of Salmonella with the secretory pathway. Here, a small-interference RNA screen revealed that secretory carrier membrane proteins (SCAMPs) 2 and 3 contribute to the maintenance of SCVs in the Golgi region of HeLa cells. This is likely to reflect a function of SCAMPs in vacuolar membrane dynamics. Moreover, SCAMP3, which accumulates on the trans-Golgi network in uninfected cells, marked tubules induced by Salmonella effectors that overlapped with SIFs but which also comprised distinct tubules lacking late endosomal proteins. We propose that SCAMP3 tubules reflect a manipulation of specific post-Golgi trafficking that might allow Salmonella to acquire nutrients and membrane, or to control host immune responses.
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Affiliation(s)
- Luís Jaime Mota
- Centre for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, UK
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