1
|
Machado LFM, Galán JE. Loss of function of metabolic traits in typhoidal Salmonella without apparent genome degradation. mBio 2024; 15:e0060724. [PMID: 38572992 PMCID: PMC11077982 DOI: 10.1128/mbio.00607-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 03/12/2024] [Indexed: 04/05/2024] Open
Abstract
Salmonella enterica serovar Typhi and Paratyphi A are the cause of typhoid and paratyphoid fever in humans, which are systemic life-threatening illnesses. Both serovars are exclusively adapted to the human host, where they can cause life-long persistent infection. A distinct feature of these serovars is the presence of a relatively high number of degraded coding sequences coding for metabolic pathways, most likely a consequence of their adaptation to a single host. As a result of convergent evolution, these serovars shared many of the degraded coding sequences although often affecting different genes in the same metabolic pathway. However, there are several coding sequences that appear intact in one serovar while clearly degraded in the other, suggesting differences in their metabolic capabilities. Here, we examined the functionality of metabolic pathways that appear intact in S. Typhi but that show clear signs of degradation in S. Paratyphi A. We found that, in all cases, the existence of single amino acid substitutions in S. Typhi metabolic enzymes, transporters, or transcription regulators resulted in the inactivation of these metabolic pathways. Thus, the inability of S. Typhi to metabolize Glucose-6-Phosphate or 3-phosphoglyceric acid is due to the silencing of the expression of the genes encoding the transporters for these compounds due to point mutations in the transcriptional regulatory proteins. In contrast, its inability to utilize glucarate or galactarate is due to the presence of point mutations in the transporter and enzymes necessary for the metabolism of these sugars. These studies provide additional support for the concept of adaptive convergent evolution of these two human-adapted S. enterica serovars and highlight a limitation of bioinformatic approaches to predict metabolic capabilities. IMPORTANCE Salmonella enterica serovar Typhi and Paratyphi A are the cause of typhoid and paratyphoid fever in humans, which are systemic life-threatening illnesses. Both serovars can only infect the human host, where they can cause life-long persistent infection. Because of their adaptation to the human host, these bacterial pathogens have changed their metabolism, leading to the loss of their ability to utilize certain nutrients. In this study we examined the functionality of metabolic pathways that appear intact in S. Typhi but that show clear signs of degradation in S. Paratyphi A. We found that, in all cases, the existence of single amino acid substitutions in S. Typhi metabolic enzymes, transporters, or transcription regulators resulted in the inactivation of these metabolic pathways. These studies provide additional support for the concept of adaptive convergent evolution of these two human-adapted S. enterica serovars.
Collapse
Affiliation(s)
- Leopoldo F. M. Machado
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| |
Collapse
|
2
|
Machado LFM, Galán JE. Loss of function of metabolic traits in typhoidal Salmonella without apparent genome degradation. bioRxiv 2024:2024.02.14.580360. [PMID: 38405738 PMCID: PMC10888927 DOI: 10.1101/2024.02.14.580360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Salmonella enterica serovar Typhi and Paratyphi A are the cause of typhoid and paratyphoid fever in humans, which are systemic life-threatening illnesses. Both serovars are exclusively adapted to the human host, where they can cause life-long persistent infection. A distinct feature of these serovars is the presence of a relatively high number of degraded coding sequences coding for metabolic pathways, most likely a consequence of their adaptation to a single host. As a result of convergent evolution, these serovars shared many of the degraded coding sequences although often affecting different genes in the same metabolic pathway. However, there are several coding sequences that appear intact in one serovar while clearly degraded in the other, suggesting differences in their metabolic capabilities. Here, we examined the functionality of metabolic pathways that appear intact in S . Typhi but that show clear signs of degradation in S . Paratyphi A. We found that, in all cases, the existence of single amino acid substitutions in S. Typhi metabolic enzymes, transporters, or transcription regulators resulted in the inactivation of these metabolic pathways. Thus, the inability of S . Typhi to metabolize Glucose-6-Phosphate or 3-phosphoglyceric acid is due to the silencing of the expression of the genes encoding the transporters for these compounds due to point mutations in the transcriptional regulatory proteins. In contrast, its inability to utilize glucarate or galactarate is due to the presence of point mutations in the transporter and enzymes necessary for the metabolism of these sugars. These studies provide additional support for the concept of adaptive convergent evolution of these two human-adapted Salmonella enterica serovars and highlight a limitation of bioinformatic approaches to predict metabolic capabilities.
Collapse
|
3
|
Lian H, Park D, Chen M, Schueder F, Lara-Tejero M, Liu J, Galán JE. Parkinson's disease kinase LRRK2 coordinates a cell-intrinsic itaconate-dependent defence pathway against intracellular Salmonella. Nat Microbiol 2023; 8:1880-1895. [PMID: 37640963 PMCID: PMC10962312 DOI: 10.1038/s41564-023-01459-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 07/24/2023] [Indexed: 08/31/2023]
Abstract
Cell-intrinsic defences constitute the first line of defence against intracellular pathogens. The guanosine triphosphatase RAB32 orchestrates one such defence response against the bacterial pathogen Salmonella, through delivery of antimicrobial itaconate. Here we show that the Parkinson's disease-associated leucine-rich repeat kinase 2 (LRRK2) orchestrates this defence response by scaffolding a complex between RAB32 and aconitate decarboxylase 1, which synthesizes itaconate from mitochondrial precursors. Itaconate delivery to Salmonella-containing vacuoles was impaired and Salmonella replication increased in LRRK2-deficient cells. Loss of LRRK2 also restored virulence of a Salmonella mutant defective in neutralizing this RAB32-dependent host defence pathway in mice. Cryo-electron tomography revealed tether formation between Salmonella-containing vacuoles and host mitochondria upon Salmonella infection, which was significantly impaired in LRRK2-deficient cells. This positions LRRK2 centrally within a host defence mechanism, which may have favoured selection of a common familial Parkinson's disease mutant allele in the human population.
Collapse
Affiliation(s)
- Huan Lian
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
- Department of Laboratory Medicine, Zhongnan Hospital of Wuhan University, Medical Research Institute, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Donghyun Park
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
- Microbial Science Institute, Yale University School of Medicine, New Haven, CT, USA
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA, USA
| | - Meixin Chen
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen, China
| | - Florian Schueder
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
- Microbial Science Institute, Yale University School of Medicine, New Haven, CT, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA.
| |
Collapse
|
4
|
Chen M, Sun H, Boot M, Shao L, Chang SJ, Wang W, Lam TT, Lara-Tejero M, Rego EH, Galán JE. Itaconate is an effector of a Rab GTPase cell-autonomous host defense pathway against Salmonella. Science 2020; 369:450-455. [PMID: 32703879 DOI: 10.1126/science.aaz1333] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 01/26/2020] [Accepted: 05/15/2020] [Indexed: 11/02/2022]
Abstract
The guanosine triphosphatase (GTPase) Rab32 coordinates a cell-intrinsic host defense mechanism that restricts the replication of intravacuolar pathogens such as Salmonella Here, we show that this mechanism requires aconitate decarboxylase 1 (IRG1), which synthesizes itaconate, a metabolite with antimicrobial activity. We find that Rab32 interacts with IRG1 on Salmonella infection and facilitates the delivery of itaconate to the Salmonella-containing vacuole. Mice defective in IRG1 rescued the virulence defect of a S. enterica serovar Typhimurium mutant specifically defective in its ability to counter the Rab32 defense mechanism. These studies provide a link between a metabolite produced in the mitochondria after stimulation of innate immune receptors and a cell-autonomous defense mechanism that restricts the replication of an intracellular bacterial pathogen.
Collapse
Affiliation(s)
- Meixin Chen
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Hui Sun
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Maikel Boot
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Lin Shao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Shu-Jung Chang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Weiwei Wang
- WM Keck Foundation Biotechnology Resource Laboratory, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Tukiet T Lam
- WM Keck Foundation Biotechnology Resource Laboratory, Yale University School of Medicine, New Haven, CT 06536, USA.,Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - E Hesper Rego
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| |
Collapse
|
5
|
Bleves S, Galán JE, Llosa M. Bacterial injection machines: Evolutionary diverse but functionally convergent. Cell Microbiol 2020; 22:e13157. [PMID: 31891220 DOI: 10.1111/cmi.13157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 12/19/2019] [Indexed: 12/23/2022]
Abstract
Many human pathogens use Type III, Type IV, and Type VI secretion systems to deliver effectors into their target cells. The contribution of these secretion systems to microbial virulence was the main focus of a workshop organised by the International University of Andalusia in Spain. The meeting addressed structure-function, substrate recruitment, and translocation processes, which differ widely on the different secretion machineries, as well as the nature of the translocated effectors and their roles in subverting the host cell. An excellent panel of worldwide speakers presented the state of the art of the field, highlighting the involvement of bacterial secretion in human disease and discussing mechanistic aspects of bacterial pathogenicity, which can provide the bases for the development of novel antivirulence strategies.
Collapse
Affiliation(s)
- Sophie Bleves
- LISM (Laboratoire d'Ingénierie des Systèmes Macromoléculaires-UMR7255), IMM (Institut de Microbiologie de la Méditerranée), Aix-Marseille Univ and CNRS, Marseille, France
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut
| | - Matxalen Llosa
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC-SODERCAN, Santander, Spain
| |
Collapse
|
6
|
Geiger T, Lara-Tejero M, Xiong Y, Galán JE. Mechanisms of substrate recognition by a typhoid toxin secretion-associated muramidase. eLife 2020; 9:53473. [PMID: 31958059 PMCID: PMC6996933 DOI: 10.7554/elife.53473] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 01/18/2020] [Indexed: 01/07/2023] Open
Abstract
Typhoid toxin is a virulence factor for the bacterial pathogen Salmonella Typhi, which causes typhoid fever in humans. After its synthesis by intracellular bacteria, typhoid toxin is secreted into the lumen of the Salmonella-containing vacuole by a secretion mechanism strictly dependent on TtsA, a specific muramidase that facilitates toxin transport through the peptidoglycan layer. Here we show that substrate recognition by TtsA depends on a discrete domain within its carboxy terminus, which targets the enzyme to the bacterial poles to recognize YcbB-edited peptidoglycan. Comparison of the atomic structures of TtsA bound to its substrate and that of a close homolog with different specificity identified specific determinants involved in substrate recognition. Combined with structure-guided mutagenesis and in vitro and in vivo crosslinking experiments, this study provides an unprecedented view of the mechanisms by which a muramidase recognizes its peptidoglycan substrate to facilitate protein secretion.
Collapse
Affiliation(s)
- Tobias Geiger
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Maria Lara-Tejero
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| | - Yong Xiong
- Department of Molecular Biophysics and BiochemistryYale University School of MedicineNew HavenUnited States
| | - Jorge E Galán
- Department of Microbial PathogenesisYale University School of MedicineNew HavenUnited States
| |
Collapse
|
7
|
Zhu S, Schniederberend M, Zhitnitsky D, Jain R, Galán JE, Kazmierczak BI, Liu J. In Situ Structures of Polar and Lateral Flagella Revealed by Cryo-Electron Tomography. J Bacteriol 2019; 201:e00117-19. [PMID: 31010901 PMCID: PMC6560136 DOI: 10.1128/jb.00117-19] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/16/2019] [Indexed: 02/07/2023] Open
Abstract
The bacterial flagellum is a sophisticated self-assembling nanomachine responsible for motility in many bacterial pathogens, including Pseudomonas aeruginosa, Vibrio spp., and Salmonella enterica The bacterial flagellum has been studied extensively in the model systems Escherichia coli and Salmonella enterica serovar Typhimurium, yet the range of variation in flagellar structure and assembly remains incompletely understood. Here, we used cryo-electron tomography and subtomogram averaging to determine in situ structures of polar flagella in P. aeruginosa and peritrichous flagella in S Typhimurium, revealing notable differences between these two flagellar systems. Furthermore, we observed flagellar outer membrane complexes as well as many incomplete flagellar subassemblies, which provide additional insight into mechanisms underlying flagellar assembly and loss in both P. aeruginosa and S Typhimurium.IMPORTANCE The bacterial flagellum has evolved as one of the most sophisticated self-assembled molecular machines, which confers locomotion and is often associated with virulence of bacterial pathogens. Variation in species-specific features of the flagellum, as well as in flagellar number and placement, results in structurally distinct flagella that appear to be adapted to the specific environments that bacteria encounter. Here, we used cutting-edge imaging techniques to determine high-resolution in situ structures of polar flagella in Pseudomonas aeruginosa and peritrichous flagella in Salmonella enterica serovar Typhimurium, demonstrating substantial variation between flagella in these organisms. Importantly, we observed novel flagellar subassemblies and provided additional insight into the structural basis of flagellar assembly and loss in both P. aeruginosa and S Typhimurium.
Collapse
Affiliation(s)
- Shiwei Zhu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, USA
| | - Maren Schniederberend
- Department of Medicine (Infectious Diseases), Yale University School of Medicine, New Haven, Connecticut, USA
| | - Daniel Zhitnitsky
- Department of Medicine (Infectious Diseases), Yale University School of Medicine, New Haven, Connecticut, USA
| | - Ruchi Jain
- Department of Medicine (Infectious Diseases), Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Barbara I Kazmierczak
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Medicine (Infectious Diseases), Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
- Microbial Sciences Institute, Yale University, West Haven, Connecticut, USA
| |
Collapse
|
8
|
Guo EZ, Desrosiers DC, Zalesak J, Tolchard J, Berbon M, Habenstein B, Marlovits T, Loquet A, Galán JE. A polymorphic helix of a Salmonella needle protein relays signals defining distinct steps in type III secretion. PLoS Biol 2019; 17:e3000351. [PMID: 31260457 PMCID: PMC6625726 DOI: 10.1371/journal.pbio.3000351] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 07/12/2019] [Accepted: 06/18/2019] [Indexed: 12/22/2022] Open
Abstract
Type III protein-secretion machines are essential for the interactions of many pathogenic or symbiotic bacterial species with their respective eukaryotic hosts. The core component of these machines is the injectisome, a multiprotein complex that mediates the selection of substrates, their passage through the bacterial envelope, and ultimately their delivery into eukaryotic target cells. The injectisome is composed of a large cytoplasmic complex or sorting platform, a multiring base embedded in the bacterial envelope, and a needle-like filament that protrudes several nanometers from the bacterial surface and is capped at its distal end by the tip complex. A characteristic feature of these machines is that their activity is stimulated by contact with target host cells. The sensing of target cells, thought to be mediated by the distal tip of the needle filament, generates an activating signal that must be transduced to the secretion machine by the needle filament. Here, through a multidisciplinary approach, including solid-state NMR (SSNMR) and cryo electron microscopy (cryo-EM) analyses, we have identified critical residues of the needle filament protein of a Salmonella Typhimurium type III secretion system that are involved in the regulation of the activity of the secretion machine. We found that mutations in the needle filament protein result in various specific phenotypes associated with different steps in the type III secretion process. More specifically, these studies reveal an important role for a polymorphic helix of the needle filament protein and the residues that line the lumen of its central channel in the control of type III secretion.
Collapse
Affiliation(s)
- Emily Z. Guo
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Daniel C. Desrosiers
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jan Zalesak
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
| | - James Tolchard
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Mélanie Berbon
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Birgit Habenstein
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Thomas Marlovits
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE) and German Electron Synchrotron Centre (DESY), Hamburg, Germany
| | - Antoine Loquet
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN-CNRS Université de Bordeaux, Pessac, France
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
9
|
Chang SJ, Jin SC, Jiao X, Galán JE. Unique features in the intracellular transport of typhoid toxin revealed by a genome-wide screen. PLoS Pathog 2019; 15:e1007704. [PMID: 30951565 PMCID: PMC6469816 DOI: 10.1371/journal.ppat.1007704] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/17/2019] [Accepted: 03/13/2019] [Indexed: 12/29/2022] Open
Abstract
Typhoid toxin is a virulence factor for Salmonella Typhi and Paratyphi, the cause of typhoid fever in humans. This toxin has a unique architecture in that its pentameric B subunit, made of PltB, is linked to two enzymatic A subunits, the ADP ribosyl transferase PltA and the deoxyribonuclease CdtB. Typhoid toxin is uniquely adapted to humans, recognizing surface glycoprotein sialoglycans terminated in acetyl neuraminic acid, which are preferentially expressed by human cells. The transport pathway to its cellular targets followed by typhoid toxin after receptor binding is currently unknown. Through a genome-wide CRISPR/Cas9-mediated screen we have characterized the mechanisms by which typhoid toxin is transported within human cells. We found that typhoid toxin hijacks specific elements of the retrograde transport and endoplasmic reticulum-associated degradation machineries to reach its subcellular destination within target cells. Our study reveals unique and common features in the transport mechanisms of bacterial toxins that could serve as the bases for the development of novel anti-toxin therapeutic strategies.
Collapse
Affiliation(s)
- Shu-Jung Chang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Sheng Chih Jin
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Xuyao Jiao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| |
Collapse
|
10
|
Abstract
Many bacteria have evolved specialized nanomachines with the remarkable ability to inject multiple bacterially encoded effector proteins into eukaryotic or prokaryotic cells. Known as type III, type IV, and type VI secretion systems, these machines play a central role in the pathogenic or symbiotic interactions between multiple bacteria and their eukaryotic hosts, or in the establishment of bacterial communities in a diversity of environments. Here we focus on recent progress elucidating the structure and assembly pathways of these machines. As many of the interactions shaped by these machines are of medical importance, they provide an opportunity to develop novel therapeutic approaches to combat important human diseases.
Collapse
Affiliation(s)
- Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
| |
Collapse
|
11
|
Lara-Tejero M, Qin Z, Hu B, Butan C, Liu J, Galán JE. Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system. PLoS Pathog 2019; 15:e1007565. [PMID: 30668610 PMCID: PMC6358110 DOI: 10.1371/journal.ppat.1007565] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/01/2019] [Accepted: 01/04/2019] [Indexed: 11/23/2022] Open
Abstract
Many bacterial pathogens and symbionts use type III secretion machines to interact with their hosts by injecting bacterial effector proteins into host target cells. A central component of this complex machine is the cytoplasmic sorting platform, which orchestrates the engagement and preparation of type III secreted proteins for their delivery to the needle complex, the substructure of the type III secretion system that mediates their passage through the bacterial envelope. The sorting platform is thought to be a dynamic structure whose components alternate between assembled and disassembled states. However, how this dynamic behavior is controlled is not understood. In S. Typhimurium a core component of the sorting platform is SpaO, which is synthesized in two tandemly translated products, a full length (SpaOL) and a short form (SpaOS) composed of the C-terminal 101 amino acids. Here we show that in the absence of SpaOS the assembly of the needle substructure of the needle complex, which requires a functional sorting platform, can still occur although with reduced efficiency. Consistent with this observation, in the absence of SpaOS secretion of effectors proteins, which requires a fully assembled injectisome, is only slightly compromised. In the absence of SpaOS we detect a significant number of fully assembled needle complexes that are not associated with fully assembled sorting platforms. We also find that although binding of SpaOL to SpaOS can be detected in the absence of other components of the sorting platform, this interaction is not detected in the context of a fully assembled sorting platform suggesting that SpaOS may not be a core structural component of the sorting platform. Consistent with this observation we find that SpaOS and OrgB, a component of the sorting platform, share the same binding surface on SpaOL. We conclude that SpaOS regulates the assembly of the sorting platform during type III secretion. Many pathogenic and symbiotic gram-negative bacteria utilize type III secretion systems to deliver bacterial proteins, known as effectors, directly into the host cell cytosol to promote their survival and the colonization of tissues. Type III secretion systems or injectisomes are large, multiprotein complexes composed of several substructures: the needle complex, a multiring structure with a protruding needle-like appendage anchored in the bacterial envelope; the export apparatus, a set of membrane proteins that form a gate in the inner-membrane for the passage of effector proteins; and the sorting platform, a large cytosolic complex that delivers the effectors to the needle complex in an orderly fashion. In this study, we characterize SpaO, the core component of the Salmonella Typhimurium sorting platform. The spaO gene encodes two simultaneously translated products, a full length protein (SpaOL) and a shorter product (SpaOS) encompassing the last 101 aa of the full length product. Here we find that in the absence of SpaOS, the sorting platform still forms and functions although slightly less efficiently than in the wild-type situation, and therefore we conclude that SpaOS is most likely not a central structural component of the sorting platform and may play a regulatory role during the cycles of assembly and disassembly that the sorting platform undergoes. In addition, we identify residues critical for the interaction between SpaOL and OrgB and SpaOL and SpaOS and conclude that those interactions might be mutually exclusive further supporting the idea that SpaOS may not be a core structural component of the sorting platform. N-terminal residues in SpaOL are shown to be critical for the formation of the sorting platform. Our findings provide insights into the sorting platform substructure, a highly conserved element in type III secretion systems and may contribute to the development of novel therapeutic avenues to fight infection.
Collapse
Affiliation(s)
- Maria Lara-Tejero
- Department of Microbial Pathogenesis Yale University School of Medicine, New haven, CT, United States of America
- * E-mail:
| | - Zhuan Qin
- Department of Microbial Pathogenesis Yale University School of Medicine, New haven, CT, United States of America
- Microbial Science Institute, Yale University School of Medicine, New haven, CT, United States of America
| | - Bo Hu
- Department of Microbiology and Molecular Genetics McGovern Medical School, The University of Texas Health Science Center at Houston, TX, United States of America
- Pathology and Laboratory Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, TX, United States of America
| | - Carmen Butan
- Department of Microbial Pathogenesis Yale University School of Medicine, New haven, CT, United States of America
| | - Jun Liu
- Department of Microbial Pathogenesis Yale University School of Medicine, New haven, CT, United States of America
- Microbial Science Institute, Yale University School of Medicine, New haven, CT, United States of America
| | - Jorge E. Galán
- Department of Microbial Pathogenesis Yale University School of Medicine, New haven, CT, United States of America
| |
Collapse
|
12
|
Park D, Lara-Tejero M, Waxham MN, Li W, Hu B, Galán JE, Liu J. Visualization of the type III secretion mediated Salmonella-host cell interface using cryo-electron tomography. eLife 2018; 7:39514. [PMID: 30281019 PMCID: PMC6175578 DOI: 10.7554/elife.39514] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 09/24/2018] [Indexed: 02/01/2023] Open
Abstract
Many important gram-negative bacterial pathogens use highly sophisticated type III protein secretion systems (T3SSs) to establish complex host-pathogen interactions. Bacterial-host cell contact triggers the activation of the T3SS and the subsequent insertion of a translocon pore into the target cell membrane, which serves as a conduit for the passage of effector proteins. Therefore the initial interaction between T3SS-bearing bacteria and host cells is the critical step in the deployment of the protein secretion machine, yet this process remains poorly understood. Here, we use high-throughput cryo-electron tomography (cryo-ET) to visualize the T3SS-mediated Salmonella-host cell interface. Our analysis reveals the intact translocon at an unprecedented level of resolution, its deployment in the host cell membrane, and the establishment of an intimate association between the bacteria and the target cells, which is essential for effector translocation. Our studies provide critical data supporting the long postulated direct injection model for effector translocation.
Collapse
Affiliation(s)
- Donghyun Park
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States.,Microbial Sciences Institute, Yale University School of Medicine, New Haven, United States
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States
| | - M Neal Waxham
- Department of Neurobiology and Anatomy, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, United States
| | - Wenwei Li
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States.,Microbial Sciences Institute, Yale University School of Medicine, New Haven, United States
| | - Bo Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, United States.,Department of Pathology and Laboratory Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, United States
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States.,Microbial Sciences Institute, Yale University School of Medicine, New Haven, United States.,Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, United States
| |
Collapse
|
13
|
Geiger T, Pazos M, Lara-Tejero M, Vollmer W, Galán JE. Peptidoglycan editing by a specific LD-transpeptidase controls the muramidase-dependent secretion of typhoid toxin. Nat Microbiol 2018; 3:1243-1254. [PMID: 30250245 DOI: 10.1038/s41564-018-0248-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 08/20/2018] [Indexed: 01/26/2023]
Abstract
Protein secretion mechanisms are essential for the virulence of most bacterial pathogens. Typhoid toxin is an essential virulence factor for Salmonella Typhi, the cause of typhoid fever in humans. This toxin is unique in that it is only produced within mammalian cells, and it must be trafficked to the extracellular space before intoxicating target cells. An essential and poorly understood aspect of this transport pathway is the secretion of typhoid toxin from the bacterium into the S. Typhi-containing vacuole. We show here that typhoid toxin secretion requires its translocation to the trans side of the peptidoglycan layer at the bacterial poles for subsequent release through the outer membrane. This translocation process depends on a specialized muramidase, the activity of which requires the localized editing of peptidoglycan by a specific ld-transpeptidase. These studies describe a protein export mechanism that is probably conserved in other bacterial species.
Collapse
Affiliation(s)
- Tobias Geiger
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Manuel Pazos
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Waldemar Vollmer
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA.
| |
Collapse
|
14
|
Sun H, Kamanova J, Lara-Tejero M, Galán JE. Salmonella stimulates pro-inflammatory signalling through p21-activated kinases bypassing innate immune receptors. Nat Microbiol 2018; 3:1122-1130. [PMID: 30224799 PMCID: PMC6158040 DOI: 10.1038/s41564-018-0246-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 08/13/2018] [Indexed: 01/11/2023]
Abstract
Microbial infections are most often countered by inflammatory responses that are initiated through the recognition of conserved microbial products by innate immune receptors and result in pathogen expulsion1-6. However, inflammation can also lead to pathology. Tissues such as the intestinal epithelium, which are exposed to microbial products, are therefore subject to stringent negative regulatory mechanisms to prevent signalling through innate immune receptors6-11. This presents a challenge to the enteric pathogen Salmonella Typhimurium, which requires intestinal inflammation to compete against the resident microbiota and to acquire the nutrients and electron acceptors that sustain its replication12,13. We show here that S. Typhimurium stimulates pro-inflammatory signalling by a unique mechanism initiated by effector proteins that are delivered by its type III protein secretion system. These effectors activate Cdc42 and the p21-activated kinase 1 (PAK1) leading to the recruitment of TNF receptor-associated factor 6 (TRAF6) and mitogen-activated protein kinase kinase kinase 7 (TAK1), and the stimulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) inflammatory signalling. The removal of Cdc42, PAK1, TRAF6 or TAK1 prevented S. Typhimurium from stimulating NF-κB signalling in cultured cells. In addition, oral administration of a highly specific PAK inhibitor blocked Salmonella-induced intestinal inflammation and bacterial replication in the mouse intestine, although it resulted in a significant increase in the bacterial loads in systemic tissues. Thus, S. Typhimurium stimulates inflammatory signalling in the intestinal tract by engaging critical downstream signalling components of innate immune receptors. These findings illustrate the unique balance that emerges from host-pathogen co-evolution, in that pathogen-initiated responses that help pathogen replication are also important to prevent pathogen spread to deeper tissues.
Collapse
Affiliation(s)
- Hui Sun
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Jana Kamanova
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA.
| |
Collapse
|
15
|
Fowler CC, Galán JE. Decoding a Salmonella Typhi Regulatory Network that Controls Typhoid Toxin Expression within Human Cells. Cell Host Microbe 2018; 23:65-76.e6. [PMID: 29324231 DOI: 10.1016/j.chom.2017.12.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 09/26/2017] [Accepted: 11/21/2017] [Indexed: 10/18/2022]
Abstract
Salmonella Typhi is the cause of typhoid fever, a major global health concern. An essential virulence factor of this pathogen is typhoid toxin. In contrast to most AB-type toxins, typhoid toxin is exclusively expressed by intracellular bacteria. The regulatory networks that ensure this unique gene expression pattern are unknown. Here, we developed FAST-INSeq, a genome-wide screening approach to identify S. Typhi genes required for typhoid toxin expression within infected cells. We find that typhoid toxin expression is controlled by a silencing and counter-silencing mechanism through the opposing actions of the PhoP/PhoQ two-component regulatory system and the histone-like protein H-NS. The screen also identified bacterial mutants that alter the proportion of intracellular S. Typhi that reside within an intravacuolar environment, which was essential for toxin expression. Collectively, these data describe a regulatory mechanism that allows a bacterial pathogen to exclusively express a virulence factor when located within a specific intracellular compartment.
Collapse
Affiliation(s)
- Casey C Fowler
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| |
Collapse
|
16
|
Gao X, Deng L, Stack G, Yu H, Chen X, Naito-Matsui Y, Varki A, Galán JE. Author Correction: Evolution of host adaptation in the Salmonella typhoid toxin. Nat Microbiol 2017; 2:1697. [PMID: 29093550 DOI: 10.1038/s41564-017-0070-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The original version of this Letter has been modified in the abstract and main text to better reflect the distribution of Neu5Ac sialoglycans in humans. Additionally, co-author Lingquan Deng's present address has been further clarified.
Collapse
Affiliation(s)
- Xiang Gao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06536, USA
| | - Lingquan Deng
- Glycobiology Research and Training Center, Departments of Medicine, Pathology and Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Gabrielle Stack
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06536, USA
| | - Hai Yu
- Department of Chemistry, University of California Davis, Davis, CA, 95616, USA
| | - Xi Chen
- Department of Chemistry, University of California Davis, Davis, CA, 95616, USA
| | - Yuko Naito-Matsui
- Glycobiology Research and Training Center, Departments of Medicine, Pathology and Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Ajit Varki
- Glycobiology Research and Training Center, Departments of Medicine, Pathology and Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06536, USA.
| |
Collapse
|
17
|
Chang SJ, Song J, Galán JE. Receptor-Mediated Sorting of Typhoid Toxin during Its Export from Salmonella Typhi-Infected Cells. Cell Host Microbe 2017; 20:682-689. [PMID: 27832592 DOI: 10.1016/j.chom.2016.10.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 09/16/2016] [Accepted: 10/09/2016] [Indexed: 11/30/2022]
Abstract
Typhoid toxin is an essential virulence factor of Salmonella Typhi, the cause of typhoid fever. Typhoid toxin is secreted into the lumen of Salmonella-containing vacuole (SCV), after which it is packaged into vesicle carrier intermediates and released extracellularly through incompletely understood mechanisms. Following export, the toxin targets cells by interacting with human-specific Neu5Ac-terminated glycan receptors. We show that typhoid toxin is sorted from the SCV into vesicle carrier intermediates via interactions of its B subunit, PltB, with specific lumenal sialylated glycan packaging receptors. Cells deficient in N-glycosylation or the synthesis of specific gangliosides or displaying Neu5Gc-terminated, as opposed to Neu5Ac-terminated, glycans do not support typhoid toxin export. Additionally, typhoid toxin packaging requires the specific SCV environment, as toxin produced by an S. Typhi mutant with impaired trafficking is not properly sorted into vesicles. These results reveal how the exotoxin of an intracellular pathogen engages host pathways for packaging and release.
Collapse
Affiliation(s)
- Shu-Jung Chang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jeongmin Song
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| |
Collapse
|
18
|
Hannemann S, Galán JE. Salmonella enterica serovar-specific transcriptional reprogramming of infected cells. PLoS Pathog 2017; 13:e1006532. [PMID: 28742135 PMCID: PMC5549772 DOI: 10.1371/journal.ppat.1006532] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/08/2017] [Accepted: 07/13/2017] [Indexed: 01/18/2023] Open
Abstract
Despite their high degree of genomic similarity, different Salmonella enterica serovars are often associated with very different clinical presentations. In humans, for example, the typhoidal S. enterica serovar Typhi causes typhoid fever, a life-threatening systemic disease. In contrast, the non-typhoidal S. enterica serovar Typhimurium causes self-limiting gastroenteritis. The molecular bases for these different clinical presentations are incompletely understood. The ability to re-program gene expression in host cells is an essential virulence factor for typhoidal and non-typhoidal S. enterica serovars. Here, we have compared the transcriptional profile of cultured epithelial cells infected with S. Typhimurium or S. Typhi. We found that both serovars stimulated distinct transcriptional responses in infected cells that are associated with the stimulation of specific signal transduction pathways. These specific responses were associated with the presence of a distinct repertoire of type III secretion effector proteins. These observations provide major insight into the molecular bases for potential differences in the pathogenic mechanisms of typhoidal and non-typhoidal S. enterica serovars. Salmonella Typhimurium and Salmonella Typhi are associated with very different clinical presentations. While S. Typhimurium causes self-limiting gastroenteritis (i. e. “food poisoning”), S. Typhi causes typhoid fever, a systemic, life-threatening disease. The bases for these major differences are not fully understood but are likely to involve many factors. We have compared the transcriptional responses of cultured cells infected with S. Typhimurium or S. Typhi. We found that these Salmonella serovars stimulated distinct transcriptional responses, which could be correlated with their ability to stimulate serovar-specific signal transduction pathways. Importantly, the ability to stimulate these cellular responses was correlated with the presence or absence of specific type III secretion effector proteins. These observations provide major insight into the molecular bases for the differences in the pathogenic mechanisms of typhoidal and non-typhoidal S. enterica serovars.
Collapse
Affiliation(s)
- Sebastian Hannemann
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
19
|
Abstract
Intracellular bacterial pathogens survive and replicate within specialized eukaryotic cell organelles. To establish their intracellular niches these pathogens have adopted sophisticated strategies to control intracellular membrane trafficking. Since Rab-family GTPases are critical regulators of endocytic and secretory membrane trafficking events, many intracellular pathogens have evolved specific mechanisms to modulate or hijack Rab GTPases dynamics and trafficking functions. One such strategy is the delivery of bacterial effectors through specialized machines to specifically target Rab GTPases. Some of these effectors functionally mimic host proteins that regulate the Rab GTP cycle, while others regulate Rabs proteins through their post-translation modifications or proteolysis. In this review, we examine how the localization and function of Rab-family GTPases are altered during infection with 3 well-studied intracellular bacterial pathogens, Mycobacterium tuberculosis, Salmonella enterica and Legionella pneumophila. We also discuss recent findings about specific mechanisms by which these intracellular pathogens target this protein family.
Collapse
Affiliation(s)
- Stefania Spanò
- a Institute of Medical Sciences, University of Aberdeen , Foresterhill , Aberdeen , UK
| | - Jorge E Galán
- b Department of Microbial Pathogenesis , Yale University School of Medicine , New Haven , CT , USA
| |
Collapse
|
20
|
Gao B, Vorwerk H, Huber C, Lara-Tejero M, Mohr J, Goodman AL, Eisenreich W, Galán JE, Hofreuter D. Metabolic and fitness determinants for in vitro growth and intestinal colonization of the bacterial pathogen Campylobacter jejuni. PLoS Biol 2017; 15:e2001390. [PMID: 28542173 PMCID: PMC5438104 DOI: 10.1371/journal.pbio.2001390] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 04/24/2017] [Indexed: 01/07/2023] Open
Abstract
Campylobacter jejuni is one of the leading infectious causes of food-borne illness around the world. Its ability to persistently colonize the intestinal tract of a broad range of hosts, including food-producing animals, is central to its epidemiology since most infections are due to the consumption of contaminated food products. Using a highly saturated transposon insertion library combined with next-generation sequencing and a mouse model of infection, we have carried out a comprehensive genome-wide analysis of the fitness determinants for growth in vitro and in vivo of a highly pathogenic strain of C. jejuni. A comparison of the C. jejuni requirements to colonize the mouse intestine with those necessary to grow in different culture media in vitro, combined with isotopologue profiling and metabolic flow analysis, allowed us to identify its metabolic requirements to establish infection, including the ability to acquire certain nutrients, metabolize specific substrates, or maintain intracellular ion homeostasis. This comprehensive analysis has identified metabolic pathways that could provide the basis for the development of novel strategies to prevent C. jejuni colonization of food-producing animals or to treat human infections.
Collapse
Affiliation(s)
- Beile Gao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Hanne Vorwerk
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | - Claudia Huber
- Lehrstuhl für Biochemie, Technische Universität München, Garching, Germany
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Juliane Mohr
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | - Andrew L. Goodman
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Microbial Sciences Institute, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | | | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail: (JEG); (DH)
| | - Dirk Hofreuter
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
- * E-mail: (JEG); (DH)
| |
Collapse
|
21
|
Fowler CC, Chang SJ, Gao X, Geiger T, Stack G, Galán JE. Emerging insights into the biology of typhoid toxin. Curr Opin Microbiol 2017; 35:70-77. [PMID: 28213043 DOI: 10.1016/j.mib.2017.01.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 01/24/2017] [Accepted: 01/25/2017] [Indexed: 11/25/2022]
Abstract
Typhoid toxin is a unique A2B5 exotoxin and an important virulence factor for Salmonella Typhi, the cause of typhoid fever. In the decade since its initial discovery, great strides have been made in deciphering the unusual biological program of this toxin, which is fundamentally different from related toxins in many ways. Purified typhoid toxin administered to laboratory animals causes many of the symptoms of typhoid fever, suggesting that typhoid toxin is a central factor in this disease. Further advances in understanding the biology of this toxin will help guide the development of badly needed diagnostics and therapeutic interventions that target this toxin to detect, prevent or treat typhoid fever.
Collapse
Affiliation(s)
- Casey C Fowler
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, United States
| | - Shu-Jung Chang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, United States
| | - Xiang Gao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, United States
| | - Tobias Geiger
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, United States
| | - Gabrielle Stack
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, United States
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, United States.
| |
Collapse
|
22
|
Dietsche T, Tesfazgi Mebrhatu M, Brunner MJ, Abrusci P, Yan J, Franz-Wachtel M, Schärfe C, Zilkenat S, Grin I, Galán JE, Kohlbacher O, Lea S, Macek B, Marlovits TC, Robinson CV, Wagner S. Structural and Functional Characterization of the Bacterial Type III Secretion Export Apparatus. PLoS Pathog 2016; 12:e1006071. [PMID: 27977800 PMCID: PMC5158082 DOI: 10.1371/journal.ppat.1006071] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 11/17/2016] [Indexed: 02/04/2023] Open
Abstract
Bacterial type III protein secretion systems inject effector proteins into eukaryotic host cells in order to promote survival and colonization of Gram-negative pathogens and symbionts. Secretion across the bacterial cell envelope and injection into host cells is facilitated by a so-called injectisome. Its small hydrophobic export apparatus components SpaP and SpaR were shown to nucleate assembly of the needle complex and to form the central “cup” substructure of a Salmonella Typhimurium secretion system. However, the in vivo placement of these components in the needle complex and their function during the secretion process remained poorly defined. Here we present evidence that a SpaP pentamer forms a 15 Å wide pore and provide a detailed map of SpaP interactions with the export apparatus components SpaQ, SpaR, and SpaS. We further refine the current view of export apparatus assembly, consolidate transmembrane topology models for SpaP and SpaR, and present intimate interactions of the periplasmic domains of SpaP and SpaR with the inner rod protein PrgJ, indicating how export apparatus and needle filament are connected to create a continuous conduit for substrate translocation. Many Gram-negative bacteria use type III secretion systems to inject bacterial proteins into eukaryotic host cells in order to promote their own survival and colonization. These systems are large molecular machines with the ability to transport proteins across three cell membranes in one step. It is believed that the only gated barrier of these systems lies in the bacterial cytoplasmic membrane but it was unclear so far how this gate looks like and of which components it is composed. Here we present evidence based on in depth biochemical and genetic characterization that an assembly of five SpaP proteins forms this gate in the cytoplasmic membrane of the type III secretion system of Salmonella pathogenicity island 1. We further show that one subunit each of the proteins SpaQ, SpaR, and SpaS are closely associated to the SpaP gate and may function in the gating mechanism, and that the protein PrgJ is attached to this gate on the outside to connect it to the hollow needle filament projecting towards the host cell. Our findings elucidate a hitherto ill-defined aspect of type III secretion systems and may help to develop novel antiinfective therapies targeting these virulence-associated molecular devices.
Collapse
Affiliation(s)
- Tobias Dietsche
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Mehari Tesfazgi Mebrhatu
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Matthias J. Brunner
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE) and German Electron Synchrotron Centre (DESY), Hamburg, Germany
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Patrizia Abrusci
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Jun Yan
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | | | | | - Susann Zilkenat
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Iwan Grin
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
| | - Jorge E. Galán
- Yale University School of Medicine, Department of Microbial Pathogenesis, New Haven, Connecticut, United States of America
| | - Oliver Kohlbacher
- University of Tübingen, Center for BioinformaticsTübingen, Germany
- Max Planck Institute for Developmental Biology, Biomolecular Interactions, Tübingen, Germany
| | - Susan Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Boris Macek
- University of Tübingen, Proteome Center Tübingen, Tübingen, Germany
| | - Thomas C. Marlovits
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE) and German Electron Synchrotron Centre (DESY), Hamburg, Germany
- Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Carol V. Robinson
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Samuel Wagner
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner-site Tübingen, Tübingen, Germany
- * E-mail:
| |
Collapse
|
23
|
Spanò S, Gao X, Hannemann S, Lara-Tejero M, Galán JE. A Bacterial Pathogen Targets a Host Rab-Family GTPase Defense Pathway with a GAP. Cell Host Microbe 2016; 19:216-26. [PMID: 26867180 DOI: 10.1016/j.chom.2016.01.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/24/2015] [Accepted: 01/19/2016] [Indexed: 12/21/2022]
Abstract
Cell-autonomous defense mechanisms are potent strategies that protect individual cells against intracellular pathogens. The Rab-family GTPase Rab32 was previously shown to restrict the intracellular human pathogen Salmonella Typhi, but its potential broader role in antimicrobial defense remains unknown. We show that Rab32 represents a general cell-autonomous, antimicrobial defense that is counteracted by two Salmonella effectors. Mice lacking Rab-32 or its nucleotide exchange factor BLOC-3 are permissive to S. Typhi infection and exhibit increased susceptibility to S. Typhimurium. S. Typhimurium counters this defense pathway by delivering two type III secretion effectors, SopD2, a Rab32 GAP, and GtgE, a specific Rab32 protease. An S. Typhimurium mutant strain lacking these two effectors exhibits markedly reduced virulence, which is fully restored in BLOC-3-deficient mice. These results demonstrate that a cell-autonomous, Rab32-dependent host defense pathway plays a central role in the defense against vacuolar pathogens and describe a mechanism evolved by a bacterial pathogen to counter it.
Collapse
Affiliation(s)
- Stefania Spanò
- Department of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA.
| | - Xiang Gao
- Department of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Sebastian Hannemann
- Department of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - María Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA.
| |
Collapse
|
24
|
Song J, Wilhelm CL, Wangdi T, Maira-Litran T, Lee SJ, Raetz M, Sturge CR, Mirpuri J, Pei J, Grishin NV, McSorley SJ, Gewirtz AT, Bäumler AJ, Pier GB, Galán JE, Yarovinsky F. Absence of TLR11 in Mice Does Not Confer Susceptibility to Salmonella Typhi. Cell 2016; 164:827-8. [PMID: 26919416 DOI: 10.1016/j.cell.2016.02.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Indexed: 11/15/2022]
Affiliation(s)
- Jeongmin Song
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Cara L Wilhelm
- Department of Immunology, University of Texas Southwestern Medical Center, TX 75390, USA
| | - Tamding Wangdi
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Tomas Maira-Litran
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Seung-Joo Lee
- Center for Comparative Medicine, Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Megan Raetz
- Department of Immunology, University of Texas Southwestern Medical Center, TX 75390, USA
| | - Carolyn R Sturge
- Department of Immunology, University of Texas Southwestern Medical Center, TX 75390, USA
| | - Julie Mirpuri
- Department of Immunology, University of Texas Southwestern Medical Center, TX 75390, USA
| | - Jimin Pei
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, TX 75390, USA; Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, TX 75390, USA
| | - Nick V Grishin
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, TX 75390, USA; Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, TX 75390, USA
| | - Stephen J McSorley
- Center for Comparative Medicine, Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Andrew T Gewirtz
- Center for Inflammation, Immunity and Infection, Georgia State University, Atlanta, GA 30303, USA
| | - Andreas J Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Gerald B Pier
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| | - Felix Yarovinsky
- Department of Immunology, University of Texas Southwestern Medical Center, TX 75390, USA; David H. Smith Center for Vaccine Biology and Immunology, Department of Microbiology and Immunology, University of Rochester, NY 14642, USA.
| |
Collapse
|
25
|
Kamanova J, Sun H, Lara-Tejero M, Galán JE. The Salmonella Effector Protein SopA Modulates Innate Immune Responses by Targeting TRIM E3 Ligase Family Members. PLoS Pathog 2016; 12:e1005552. [PMID: 27058235 PMCID: PMC4825927 DOI: 10.1371/journal.ppat.1005552] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 03/14/2016] [Indexed: 12/22/2022] Open
Abstract
Salmonella Typhimurium stimulates inflammatory responses in the intestinal epithelium, which are essential for its ability to replicate within the intestinal tract. Stimulation of these responses is strictly dependent on the activity of a type III secretion system encoded within its pathogenicity island 1, which through the delivery of effector proteins, triggers signaling pathways leading to inflammation. One of these effectors is SopA, a HECT-type E3 ligase, which is required for the efficient stimulation of inflammation in an animal model of Salmonella Typhimurium infection. We show here that SopA contributes to the stimulation of innate immune responses by targeting two host E3 ubiquitin ligases, TRIM56 and TRIM65. We also found that TRIM65 interacts with the innate immune receptor MDA5 enhancing its ability to stimulate interferon-β signaling. Therefore, by targeting TRIM56 and TRIM65, SopA can stimulate signaling through two innate immune receptors, RIG-I and MDA5. These findings describe a Salmonella mechanism to modulate inflammatory responses by directly targeting innate immune signaling mechanisms. Salmonella Typhimurium, one of the main causes of food-borne illnesses, stimulates inflammatory responses in the intestinal epithelium. These responses are very important for the pathogen’s ability to secure nutrients within the intestinal tract. The ability of this pathogen to stimulate intestinal inflammation depends on a protein-delivery machine known as the type III secretion system. This system “injects” bacterial effector protein into host cells to modulate a variety of cellular functions for the pathogen’s benefit. We show here that one of these effector proteins, SopA, stimulates signaling pathways that can lead to inflammation. We report that SopA exerts its function by targeting two host E3 ubiquitin ligases, TRIM56 and TRIM65, which have the ability to enhance interferon-β expression through the innate immune receptors RIG-I and MDA5. These findings describe a Salmonella mechanism to stimulate inflammation by directly targeting innate immune signaling mechanisms.
Collapse
Affiliation(s)
- Jana Kamanova
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Hui Sun
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
26
|
Sun H, Kamanova J, Lara-Tejero M, Galán JE. A Family of Salmonella Type III Secretion Effector Proteins Selectively Targets the NF-κB Signaling Pathway to Preserve Host Homeostasis. PLoS Pathog 2016; 12:e1005484. [PMID: 26933955 PMCID: PMC4775039 DOI: 10.1371/journal.ppat.1005484] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/10/2016] [Indexed: 12/11/2022] Open
Abstract
Microbial infections usually lead to host innate immune responses and inflammation. These responses most often limit pathogen replication although they can also result in host-tissue damage. The enteropathogenic bacteria Salmonella Typhimurium utilizes a type III secretion system to induce intestinal inflammation by delivering specific effector proteins that stimulate signal transduction pathways resulting in the production of pro-inflammatory cytokines. We show here that a family of related Salmonella Typhimurium effector proteins PipA, GogA and GtgA redundantly target components of the NF-κB signaling pathway to inhibit transcriptional responses leading to inflammation. We show that these effector proteins are proteases that cleave both the RelA (p65) and RelB transcription factors but do not target p100 (NF-κB2) or p105 (NF-κB1). A Salmonella Typhimurium strain lacking these effectors showed increased ability to stimulate NF-κB and increased virulence in an animal model of infection. These results indicate that bacterial pathogens can evolve determinants to preserve host homeostasis and that those determinants can reduce the pathogen’s virulence. The inflammatory response to microbial pathogens usually limits their replication but it can also cause tissue damage. The enteropathogenic bacteria Salmonella Typhimurium stimulate host signal transduction pathways that result in inflammation. We show here that a family of related Salmonella Typhimurium effector proteins, PipA, GogA and GtgA, which are delivered by its type III secretion systems, specifically and redundantly target components of the NF-κB signaling pathway to inhibit transcriptional responses leading to host inflammation. We show that these effector proteins are proteases that cleave both the RelA (p65) and RelB transcription factors, which are central components of the NF-κB signaling pathway, but do not target p100 (NF-κB2) or p105 (NF-κB1). A Salmonella Typhimurium mutant strain lacking these effector proteins showed increased ability to stimulate NF-κB and increased virulence in an animal model of infection. These results indicate that bacterial pathogens can evolve determinants to preserve host homeostasis.
Collapse
Affiliation(s)
- Hui Sun
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jana Kamanova
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
27
|
Zilkenat S, Franz-Wachtel M, Stierhof YD, Galán JE, Macek B, Wagner S. Determination of the Stoichiometry of the Complete Bacterial Type III Secretion Needle Complex Using a Combined Quantitative Proteomic Approach. Mol Cell Proteomics 2016; 15:1598-609. [PMID: 26900162 DOI: 10.1074/mcp.m115.056598] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Indexed: 11/06/2022] Open
Abstract
Precisely knowing the stoichiometry of their components is critical for investigating structure, assembly, and function of macromolecular machines. This has remained a technical challenge in particular for large, hydrophobic membrane-spanning protein complexes. Here, we determined the stoichiometry of a type III secretion system of Salmonella enterica serovar Typhimurium using two complementary protocols of gentle complex purification combined with peptide concatenated standard and synthetic stable isotope-labeled peptide-based mass spectrometry. Bacterial type III secretion systems are cell envelope-spanning effector protein-delivery machines essential for colonization and survival of many Gram-negative pathogens and symbionts. The membrane-embedded core unit of these secretion systems, termed the needle complex, is composed of a base that anchors the machinery to the inner and outer membranes, a hollow filament formed by inner rod and needle subunits that serves as conduit for substrate proteins, and a membrane-embedded export apparatus facilitating substrate translocation. Structural analyses have revealed the stoichiometry of the components of the base, but the stoichiometry of the essential hydrophobic export apparatus components and of the inner rod protein remain unknown. Here, we provide evidence that the export apparatus of type III secretion systems contains five SpaP, one SpaQ, one SpaR, and one SpaS. We confirmed that the previously suggested stoichiometry of nine InvA is valid for assembled needle complexes and describe a loose association of InvA with other needle complex components that may reflect its function. Furthermore, we present evidence that not more than six PrgJ form the inner rod of the needle complex. Providing this structural information will facilitate efforts to obtain an atomic view of type III secretion systems and foster our understanding of the function of these and related flagellar machines. Given that other virulence-associated bacterial secretion systems are similar in their overall buildup and complexity, the presented approach may also enable their stoichiometry elucidation.
Collapse
Affiliation(s)
- Susann Zilkenat
- From the ‡University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
| | - Mirita Franz-Wachtel
- §University of Tübingen, Proteome Center Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - York-Dieter Stierhof
- ¶University of Tübingen, Center for Plant Molecular Biology (ZMBP), Auf der Morgenstelle 32, 72076 Tübingen, Germany
| | - Jorge E Galán
- ‖Yale University School of Medicine, Department of Microbial Pathogenesis, 295 Congress Ave, New Haven, CT
| | - Boris Macek
- §University of Tübingen, Proteome Center Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Samuel Wagner
- From the ‡University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany; **German Center for Infection Research (DZIF), Partner-site Tübingen, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany
| |
Collapse
|
28
|
Tsou LK, Lara-Tejero M, RoseFigura J, Zhang ZJ, Wang YC, Yount JS, Lefebre M, Dossa PD, Kato J, Guan F, Lam W, Cheng YC, Galán JE, Hang HC. Antibacterial Flavonoids from Medicinal Plants Covalently Inactivate Type III Protein Secretion Substrates. J Am Chem Soc 2016; 138:2209-18. [PMID: 26847396 DOI: 10.1021/jacs.5b11575] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Traditional Chinese Medicines (TCMs) have been historically used to treat bacterial infections. However, the molecules responsible for these anti-infective properties and their potential mechanisms of action have remained elusive. Using a high-throughput assay for type III protein secretion in Salmonella enterica serovar Typhimurium, we discovered that several TCMs can attenuate this key virulence pathway without affecting bacterial growth. Among the active TCMs, we discovered that baicalein, a specific flavonoid from Scutellaria baicalensis, targets S. Typhimurium pathogenicity island-1 (SPI-1) type III secretion system (T3SS) effectors and translocases to inhibit bacterial invasion of epithelial cells. Structurally related flavonoids present in other TCMs, such as quercetin, also inactivated the SPI-1 T3SS and attenuated S. Typhimurium invasion. Our results demonstrate that specific plant metabolites from TCMs can directly interfere with key bacterial virulence pathways and reveal a previously unappreciated mechanism of action for anti-infective medicinal plants.
Collapse
Affiliation(s)
- Lun K Tsou
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States.,Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes , Zhunan Town, Miaoli County 35053, Taiwan, R.O.C
| | - María Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Jordan RoseFigura
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Zhenrun J Zhang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Yen-Chih Wang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Jacob S Yount
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Matthew Lefebre
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Paul D Dossa
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Junya Kato
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Fulan Guan
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Wing Lam
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Yung-Chi Cheng
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Howard C Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| |
Collapse
|
29
|
Deng L, Song J, Gao X, Wang J, Yu H, Chen X, Varki N, Naito-Matsui Y, Galán JE, Varki A. Host adaptation of a bacterial toxin from the human pathogen Salmonella Typhi. Cell 2015; 159:1290-9. [PMID: 25480294 DOI: 10.1016/j.cell.2014.10.057] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/09/2014] [Accepted: 10/28/2014] [Indexed: 10/24/2022]
Abstract
Salmonella Typhi is an exclusive human pathogen that causes typhoid fever. Typhoid toxin is a S. Typhi virulence factor that can reproduce most of the typhoid fever symptoms in experimental animals. Toxicity depends on toxin binding to terminally sialylated glycans on surface glycoproteins. Human glycans are unusual because of the lack of CMAH, which in other mammals converts N-acetylneuraminic acid (Neu5Ac) to N-glycolylneuraminic acid (Neu5Gc). Here, we report that typhoid toxin binds to and is toxic toward cells expressing glycans terminated in Neu5Ac (expressed by humans) over glycans terminated in Neu5Gc (expressed by other mammals). Mice constitutively expressing CMAH thus displaying Neu5Gc in all tissues are resistant to typhoid toxin. The atomic structure of typhoid toxin bound to Neu5Ac reveals the structural bases for its binding specificity. These findings provide insight into the molecular bases for Salmonella Typhi's host specificity and may help the development of therapies for typhoid fever.
Collapse
Affiliation(s)
- Lingquan Deng
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093, USA; Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jeongmin Song
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Xiang Gao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jiawei Wang
- School of Life Sciences, Tsinghua University, Beijing 100084, PRC
| | - Hai Yu
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Xi Chen
- Department of Chemistry, University of California, Davis, Davis, CA 95616, USA
| | - Nissi Varki
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093, USA; Department of Pathology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yuko Naito-Matsui
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093, USA; Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| | - Ajit Varki
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093, USA; Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Pathology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| |
Collapse
|
30
|
Gao B, Lara-Tejero M, Lefebre M, Goodman AL, Galán JE. Novel components of the flagellar system in epsilonproteobacteria. mBio 2014; 5:e01349-14. [PMID: 24961693 PMCID: PMC4073491 DOI: 10.1128/mbio.01349-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Accepted: 06/02/2014] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED Motility is essential for the pathogenesis of many bacterial species. Most bacteria move using flagella, which are multiprotein filaments that rotate propelled by a cell wall-anchored motor using chemical energy. Although some components of the flagellar apparatus are common to many bacterial species, recent studies have shown significant differences in the flagellar structures of different bacterial species. The molecular bases for these differences, however, are not understood. The flagella from epsilonproteobacteria, which include the bacterial pathogens Campylobacter jejuni and Helicobacter pylori, are among the most divergent. Using next-generation sequencing combined with transposon mutagenesis, we have conducted a comprehensive high-throughput genetic screen in Campylobacter jejuni, which identified several novel components of its flagellar system. Biochemical analyses detected interactions between the identified proteins and known components of the flagellar machinery, and in vivo imaging located them to the bacterial poles, where flagella assemble. Most of the identified new components are conserved within but restricted to epsilonproteobacteria. These studies provide insight into the divergent flagella of this group of bacteria and highlight the complexity of this remarkable structure, which has adapted to carry out its conserved functions in the context of widely diverse bacterial species. IMPORTANCE Motility is essential for the normal physiology and pathogenesis of many bacterial species. Most bacteria move using flagella, which are multiprotein filaments that rotate propelled by a motor that uses chemical energy as fuel. Although some components of the flagellar apparatus are common to many bacterial species, recent studies have shown significant divergence in the flagellar structures across bacterial species. However, the molecular bases for these differences are not understood. The flagella from epsilonproteobacteria, which include the bacterial pathogens Campylobacter jejuni and Helicobacter pylori, are among the most divergent. We conducted a comprehensive genetic screen in Campylobacter jejuni and identified several novel components of the flagellar system. These studies provide important information to understand how flagella have adapted to function in the context of widely diverse sets of bacterial species and bring unique insight into the evolution and function of this remarkable bacterial organelle.
Collapse
Affiliation(s)
- Beile Gao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Matthew Lefebre
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | | | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| |
Collapse
|
31
|
Galán JE, Lara-Tejero M, Marlovits TC, Wagner S. Bacterial type III secretion systems: specialized nanomachines for protein delivery into target cells. Annu Rev Microbiol 2014; 68:415-38. [PMID: 25002086 DOI: 10.1146/annurev-micro-092412-155725] [Citation(s) in RCA: 360] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
One of the most exciting developments in the field of bacterial pathogenesis in recent years is the discovery that many pathogens utilize complex nanomachines to deliver bacterially encoded effector proteins into target eukaryotic cells. These effector proteins modulate a variety of cellular functions for the pathogen's benefit. One of these protein-delivery machines is the type III secretion system (T3SS). T3SSs are widespread in nature and are encoded not only by bacteria pathogenic to vertebrates or plants but also by bacteria that are symbiotic to plants or insects. A central component of T3SSs is the needle complex, a supramolecular structure that mediates the passage of the secreted proteins across the bacterial envelope. Working in conjunction with several cytoplasmic components, the needle complex engages specific substrates in sequential order, moves them across the bacterial envelope, and ultimately delivers them into eukaryotic cells. The central role of T3SSs in pathogenesis makes them great targets for novel antimicrobial strategies.
Collapse
Affiliation(s)
- Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut 06536;
| | | | | | | |
Collapse
|
32
|
Kohler AC, Spanò S, Galán JE, Stebbins CE. Structural and enzymatic characterization of a host-specificity determinant from Salmonella. Acta Crystallogr D Biol Crystallogr 2014; 70:384-91. [PMID: 24531472 PMCID: PMC3940199 DOI: 10.1107/s1399004713028393] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 10/15/2013] [Indexed: 12/18/2022]
Abstract
GtgE is an effector protein from Salmonella Typhimurium that modulates trafficking of the Salmonella-containing vacuole. It exerts its function by cleaving the Rab-family GTPases Rab29, Rab32 and Rab38, thereby preventing the delivery of antimicrobial factors to the bacteria-containing vacuole. Here, the crystal structure of GtgE at 1.65 Å resolution is presented, and structure-based mutagenesis and in vivo infection assays are used to identify its catalytic triad. A panel of cysteine protease inhibitors were examined and it was determined that N-ethylmaleimide, antipain and chymostatin inhibit GtgE activity in vitro. These findings provide the basis for the development of novel therapeutic strategies to combat Salmonella infections.
Collapse
Affiliation(s)
- Amanda C. Kohler
- Laboratory of Structural Microbiology, Rockefeller University, New York, NY 10065, USA
| | - Stefania Spanò
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - C. Erec Stebbins
- Laboratory of Structural Microbiology, Rockefeller University, New York, NY 10065, USA
| |
Collapse
|
33
|
Abstract
Salmonella enterica is a bacterial pathogen that closely interacts with its host and replicates intracellularly. It has evolved the ability to create an intracellular membrane vacuole where it can survive and replicate. The nature of the Salmonella vacuole is still poorly understood, and although it has some features in common with lysosomes, it serves as a suitable niche for its survival. In contrast to broad-host Salmonella enterica serovars, Salmonella enterica serovar Typhi (S. Typhi) is a host-adapted pathogen that does not have the ability to replicate in any species other than humans. Such host adaptation is manifested at the single cell level since this pathogen is unable to survive in non-human macrophages. We recently reported that a pathway dependent on the Rab GTPase Rab32 and its guanine-nucleotide exchange factor BLOC-3 restricts the growth and survival of S. Typhi in non-permissive macrophages. We also found that broad host Salmonellae, such as S. Typhimurium, are able to antagonize this pathway by delivering a bacterial effector protein that specifically cleaves Rab32 resulting in its degradation.
Collapse
Affiliation(s)
- Stefania Spanò
- Department of Microbial Pathogenesis; Yale University School of Medicine; New Haven, CT USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis; Yale University School of Medicine; New Haven, CT USA
| |
Collapse
|
34
|
Abstract
Salmonella Typhimurium has evolved a complex functional interface with its host cell largely determined by two type III secretion systems (T3SS), which through the delivery of bacterial effector proteins modulate a variety of cellular processes. We show here that Salmonella Typhimurium infection of epithelial cells results in a profound transcriptional reprogramming that changes over time. This response is triggered by Salmonella T3SS effector proteins, which stimulate unique signal transduction pathways leading to STAT3 activation. We found that the Salmonella-stimulated changes in host cell gene expression are required for the formation of its specialized vesicular compartment that is permissive for its intracellular replication. This study uncovers a cell-autonomous process required for Salmonella pathogenesis potentially opening up new avenues for the development of anti-infective strategies that target relevant host pathways. Essential for the ability of Salmonella Typhimurium to cause disease is the function of a type III secretion system (T3SS) encoded within its pathogenicity island 1 (SPI-1), which through the delivery of bacterial effector proteins modulates a variety of cellular functions. This study reports that the infection of mammalian cells with Salmonella Typhimurium results in a profound reprogramming of gene expression that changes over time. The stimulation of this response requires the activity of a specific subset of bacterial T3SS effector proteins, which stimulate unique signal transduction pathways leading to STAT3 activation. We found that the Salmonella-stimulated changes in host cell gene expression are required for its intracellular replication. Targeting the mechanisms described in this study may lead to the development of novel anti-infective strategies.
Collapse
Affiliation(s)
- Sebastian Hannemann
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Beile Gao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
35
|
Abstract
Salmonella enterica serovar Typhi (S. Typhi) differs from most other salmonellae in that it causes a life-threatening systemic infection known as typhoid fever. The molecular bases for its unique clinical presentation are unknown. Here we find that the systemic administration of typhoid toxin, a unique virulence factor of S. Typhi, reproduces many of the acute symptoms of typhoid fever in an animal model. We identify specific carbohydrate moieties on specific surface glycoproteins that serve as receptors for typhoid toxin, which explains its broad cell target specificity. We present the atomic structure of typhoid toxin, which shows an unprecedented A2B5 organization with two covalently linked A subunits non-covalently associated to a pentameric B subunit. The structure provides insight into the toxin's receptor-binding specificity and delivery mechanisms and reveals how the activities of two powerful toxins have been co-opted into a single, unique toxin that can induce many of the symptoms characteristic of typhoid fever. These findings may lead to the development of potentially life-saving therapeutics against typhoid fever.
Collapse
Affiliation(s)
| | | | - Jorge E. Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536
| |
Collapse
|
36
|
Abstract
Unlike other Salmonellae, the intracellular bacterial human pathogen Salmonella Typhi exhibits strict host specificity. The molecular bases for this restriction are unknown. Here we found that the expression of a single type III secretion system effector protein from broad-host Salmonella Typhimurium allowed Salmonella Typhi to survive and replicate within macrophages and tissues from mice, a nonpermissive host. This effector proteolytically targeted Rab32, which controls traffic to lysosome-related organelles in conjunction with components of the biogenesis of lysosome-related organelle complexes (BLOCs). RNA interference-mediated depletion of Rab32 or of an essential component of a BLOC complex was sufficient to allow S. Typhi to survive within mouse macrophages. Furthermore, S. Typhi was able to survive in macrophages from mice defective in BLOC components.
Collapse
Affiliation(s)
- Stefania Spanò
- Department of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | | |
Collapse
|
37
|
Liu X, Gao B, Novik V, Galán JE. Quantitative Proteomics of Intracellular Campylobacter jejuni Reveals Metabolic Reprogramming. PLoS Pathog 2012; 8:e1002562. [PMID: 22412372 PMCID: PMC3297583 DOI: 10.1371/journal.ppat.1002562] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 01/19/2012] [Indexed: 01/11/2023] Open
Abstract
Campylobacter jejuni is the major cause of bacterial food-borne illness in the USA and Europe. An important virulence attribute of this bacterial pathogen is its ability to enter and survive within host cells. Here we show through a quantitative proteomic analysis that upon entry into host cells, C. jejuni undergoes a significant metabolic downshift. Furthermore, our results indicate that intracellular C. jejuni reprograms its respiration, favoring the respiration of fumarate. These results explain the poor ability of C. jejuni obtained from infected cells to grow under standard laboratory conditions and provide the bases for the development of novel anti microbial strategies that would target relevant metabolic pathways. Campylobacter jejuni is one of the most common causes of food-borne illness in the United States and a major cause of diarrheal diseases in developing countries. This pathogen can invade intestinal epithelial cells, which is very important for its ability to cause disease. Once it gains access to epithelial cells, C. jejuni becomes unable to grow under standard growth conditions, although it can grow if pre-incubated under oxygen limiting conditions. This study compares the protein compositions of C. jejuni grown under standard growth conditions and obtained from within epithelial cells. This analysis indicates that, within cells, C. jejuni undergoes a significant metabolic downshift and reprograms its respiration, favoring the respiration of fumarate. These results may provide the bases for the development of novel anti microbial strategies that would target relevant metabolic pathways.
Collapse
Affiliation(s)
| | | | | | - Jorge E. Galán
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
38
|
Hicks SW, Charron G, Hang HC, Galán JE. Subcellular targeting of Salmonella virulence proteins by host-mediated S-palmitoylation. Cell Host Microbe 2011; 10:9-20. [PMID: 21767808 DOI: 10.1016/j.chom.2011.06.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 05/19/2011] [Accepted: 06/14/2011] [Indexed: 10/17/2022]
Abstract
Several pathogenic bacteria utilize type III secretion systems (TTSS) to deliver into host cells bacterial virulence proteins with the capacity to modulate a variety of cellular pathways. Once delivered into host cells, the accurate targeting of bacterial effectors to specific locations is critical for their proper function. However, little is known about the mechanisms these virulence effectors use to reach their subcellular destination. Here we show that the Salmonella TTSS effector proteins SspH2 and SseI are localized to the plasma membrane of host cells, a process dependent on S-palmitoylation of a conserved cysteine residue within their N-terminal domains. We also show that effector protein lipidation is mediated by a specific subset of host-cell palmitoyltransferases and that lipidation is critical for effector function. This study describes a remarkable mechanism by which a pathogen exploits host-cell machinery to properly target its virulence factors.
Collapse
Affiliation(s)
- Stuart W Hicks
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | | | | | | |
Collapse
|
39
|
Abstract
Type III protein secretion systems (T3SSs), which have evolved to deliver bacterial proteins into nucleated cells, are found in many species of Gram-negative bacteria that live in close association with eukaryotic hosts. Proteins destined to travel this secretion pathway are targeted to the secretion machine by customized chaperones, with which they form highly structured complexes. Here, we have identified a mechanism that co-ordinates the expression of the Salmonella Typhimurium T3SS chaperone SicP and its cognate effector SptP. Translation of the effector is coupled to that of its chaperone, and in the absence of translational coupling, an inhibitory RNA structure prevents translation of sptP. The data presented here show how the genomic organization of functionally related proteins can have a significant impact on the co-ordination of their expression.
Collapse
Affiliation(s)
- Julie E Button
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | | |
Collapse
|
40
|
Abstract
Bacterial type III protein secretion systems deliver effector proteins into eukaryotic cells in order to modulate cellular processes. Central to the function of these protein-delivery machines is their ability to recognize and secrete substrates in a defined order. Here, we describe a mechanism by which a type III secretion system from the bacterial enteropathogen Salmonella enterica serovar Typhimurium can sort its substrates before secretion. This mechanism involves a cytoplasmic sorting platform that is sequentially loaded with the appropriate secreted proteins. The sequential loading of this platform, facilitated by customized chaperones, ensures the hierarchy in type III protein secretion. Given the presence of these machines in many important pathogens, these findings can serve as the bases for the development of novel antimicrobial strategies.
Collapse
Affiliation(s)
- María Lara-Tejero
- Section of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Junya Kato
- Section of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Samuel Wagner
- Section of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Xiaoyun Liu
- Section of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Jorge E. Galán
- Section of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| |
Collapse
|
41
|
Song J, Willinger T, Rongvaux A, Eynon EE, Stevens S, Manz MG, Flavell RA, Galán JE. A mouse model for the human pathogen Salmonella typhi. Cell Host Microbe 2011; 8:369-76. [PMID: 20951970 DOI: 10.1016/j.chom.2010.09.003] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 07/11/2010] [Accepted: 07/26/2010] [Indexed: 01/12/2023]
Abstract
Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever, a life-threatening human disease. The lack of animal models due to S. Typhi's strict human host specificity has hindered its study and vaccine development. We find that immunodeficient Rag2(-/-) γc(-/-) mice engrafted with human fetal liver hematopoietic stem and progenitor cells are able to support S. Typhi replication and persistent infection. A S. Typhi mutant in a gene required for virulence in humans was unable to replicate in these mice. Another mutant unable to produce typhoid toxin exhibited increased replication, suggesting a role for this toxin in the establishment of persistent infection. Furthermore, infected animals mounted human innate and adaptive immune responses to S. Typhi, resulting in the production of cytokines and pathogen-specific antibodies. We expect that this mouse model will be a useful resource for understanding S. Typhi pathogenesis and for evaluating potential vaccine candidates against typhoid fever.
Collapse
Affiliation(s)
- Jeongmin Song
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06520, USA
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Hicks SW, Galán JE. Hijacking the host ubiquitin pathway: structural strategies of bacterial E3 ubiquitin ligases. Curr Opin Microbiol 2009; 13:41-6. [PMID: 20036613 DOI: 10.1016/j.mib.2009.11.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 11/23/2009] [Accepted: 11/28/2009] [Indexed: 01/24/2023]
Abstract
Ubiquitinylation of proteins is a critical mechanism in regulating numerous eukaryotic cellular processes including cell cycle progression, inflammatory response, and vesicular trafficking. Given the importance of ubiquitinylation, it is not surprising that several pathogenic bacteria have developed strategies to exploit various stages of the ubiquitin pathway for their own benefit. One such strategy is the delivery of bacterial 'effector' proteins into the host cell cytosol, which mimic the activities of components of the host ubiquitin pathway. Recent studies have highlighted a number of bacterial effectors that functionally mimic the activity of eukaryotic E3 ubiquitin ligases, including a novel structural class of bacterial E3 ligases that provides a striking example of convergent evolution.
Collapse
Affiliation(s)
- Stuart W Hicks
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06519, USA
| | | |
Collapse
|
43
|
Du F, Galán JE. Selective inhibition of type III secretion activated signaling by the Salmonella effector AvrA. PLoS Pathog 2009; 5:e1000595. [PMID: 19779561 PMCID: PMC2742890 DOI: 10.1371/journal.ppat.1000595] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 08/27/2009] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica utilizes a type III secretion system (TTSS) encoded in its pathogenicity island 1 to mediate its initial interactions with intestinal epithelial cells, which are characterized by the stimulation of actin cytoskeleton reorganization and a profound reprogramming of gene expression. These responses result from the stimulation of Rho-family GTPases and downstream signaling pathways by specific effector proteins delivered by this TTSS. We show here that AvrA, an effector protein of this TTSS, specifically inhibits the Salmonella-induced activation of the JNK pathway through its interaction with MKK7, although it does not interfere with the bacterial infection-induced NF-κB activation. We also show that AvrA is phosphorylated at evolutionary conserved residues by a TTSS-effector-activated ERK pathway. This interplay between effector proteins delivered by the same TTSS highlights the remarkable complexity of these systems. Salmonella Typhimurium is a major cause of diarrheal disease worldwide. Central to S. Typhimurium's pathogenesis is its ability to induce intestinal inflammation, which is initiated by several bacterial proteins injected into intestinal epithelial cells by a nanomachine known as the type III secretion system. We show here that another bacterial protein injected by this machine negatively influences the responses triggered by Salmonella, presumably to limit cellular damage. This interplay between bacterial proteins of opposite function highlights the remarkable complexity of the host/pathogen interface.
Collapse
Affiliation(s)
- Fangyong Du
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E. Galán
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
44
|
Bruno VM, Hannemann S, Lara-Tejero M, Flavell RA, Kleinstein SH, Galán JE. Salmonella Typhimurium type III secretion effectors stimulate innate immune responses in cultured epithelial cells. PLoS Pathog 2009; 5:e1000538. [PMID: 19662166 PMCID: PMC2714975 DOI: 10.1371/journal.ppat.1000538] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 07/13/2009] [Indexed: 12/31/2022] Open
Abstract
Recognition of conserved bacterial products by innate immune receptors leads to inflammatory responses that control pathogen spread but that can also result in pathology. Intestinal epithelial cells are exposed to bacterial products and therefore must prevent signaling through innate immune receptors to avoid pathology. However, enteric pathogens are able to stimulate intestinal inflammation. We show here that the enteric pathogen Salmonella Typhimurium can stimulate innate immune responses in cultured epithelial cells by mechanisms that do not involve receptors of the innate immune system. Instead, S. Typhimurium stimulates these responses by delivering through its type III secretion system the bacterial effector proteins SopE, SopE2, and SopB, which in a redundant fashion stimulate Rho-family GTPases leading to the activation of mitogen-activated protein (MAP) kinase and NF-κB signaling. These observations have implications for the understanding of the mechanisms by which Salmonella Typhimurium induces intestinal inflammation as well as other intestinal inflammatory pathologies. Salmonella Typhimurium is one of the most common causes of food-borne illness in the United States and a major cause of diarrheal diseases in developing countries. This pathogen induces diarrhea by stimulating inflammation in the intestinal tract. This study shows that S. Typhimurium delivers molecules into epithelial cells with the capacity to stimulate the production of pro-inflammatory substances. This mechanism may help the pathogen to initiate the inflammatory response in the intestinal epithelium. This study provides insight into the mechanisms by which Salmonella Typhimurium causes diarrhea.
Collapse
Affiliation(s)
- Vincent M. Bruno
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Sebastian Hannemann
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - María Lara-Tejero
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Richard A. Flavell
- Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Steven H. Kleinstein
- Department of Pathology and Interdepartmental Program in Computational Biology and Bioinformatics, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E. Galán
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
| |
Collapse
|
45
|
Abstract
Central to the biology of many pathogenic bacteria are a number of specialized machines, known as type III, type IV, or type VI protein secretion systems. These machines have specifically evolved to deliver bacterial effector proteins into host cells with the capacity to modulate a variety of cellular functions. The identification of the biochemical activities of many effector proteins, coupled with a better understanding of their potential contribution to pathogenesis, has revealed common themes in the evolutionary design and function of these remarkable bacterial proteins.
Collapse
Affiliation(s)
- Jorge E Galán
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| |
Collapse
|
46
|
Hofreuter D, Novik V, Galán JE. Metabolic diversity in Campylobacter jejuni enhances specific tissue colonization. Cell Host Microbe 2008; 4:425-33. [PMID: 18996343 DOI: 10.1016/j.chom.2008.10.002] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 09/15/2008] [Accepted: 10/02/2008] [Indexed: 11/19/2022]
Abstract
Campylobacter jejuni is a leading cause of foodborne illness in industrialized countries. This pathogen exhibits significant strain-to-strain variability, which results in differences in virulence potential and clinical presentations. Here, we report that acquisition of the capacity to utilize specific nutrients enhanced the ability of a highly pathogenic strain of C. jejuni to colonize specific tissues. The acquisition of a gene encoding a gamma-glutamyltranspeptidase enabled this strain to utilize glutamine and glutathione and enhanced its ability to colonize the intestine. Furthermore, the acquisition of a DNA segment, which added a sec-dependent secretion signal to an otherwise cytoplasmic asparaginase, allowed this pathogen to utilize asparagine and to more efficiently colonize the liver. Our results reveal that subtle genetic changes in a bacterial pathogen result in significant changes in its ability to colonize specific tissues. In addition, these studies revealed remarkably specific nutritional requirements for a pathogen to effectively colonize different tissues.
Collapse
Affiliation(s)
- Dirk Hofreuter
- Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | | | | |
Collapse
|
47
|
Spanò S, Galán JE. A novel pathway for exotoxin delivery by an intracellular pathogen. Curr Opin Microbiol 2008; 11:15-20. [PMID: 18243772 DOI: 10.1016/j.mib.2007.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 12/14/2007] [Accepted: 12/18/2007] [Indexed: 12/28/2022]
Abstract
Fundamental to the biology of many bacterial pathogens are bacterial proteins with the capacity to modulate host cellular functions. These bacterial proteins are delivered to the host's molecular targets by a great diversity of mechanisms of varying complexity. The different delivery mechanisms are adapted to the specific biology of the pathogen. Here we focus our attention on a recently described delivery pathway adapted to the biology of an intracellular pathogen, in which an exotoxin is delivered from an intracellular location to its molecular target through autocrine and paracrine pathways.
Collapse
Affiliation(s)
- Stefania Spanò
- Section of Microbial Pathogenesis, Yale University School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT 06536, USA
| | | |
Collapse
|
48
|
Abstract
Campylobacter jejuni is one of the major causes of infectious diarrhea world-wide, although relatively little is know about its mechanisms of pathogenicity. This bacterium can gain entry into intestinal epithelial cells, which is thought to be important for its ability to persistently infect and cause disease. We found that C. jejuni is able to survive within intestinal epithelial cells. However, recovery of intracellular bacteria required pre-culturing under oxygen-limiting conditions, suggesting that C. jejuni undergoes significant physiological changes within the intracellular environment. We also found that in epithelial cells the C. jejuni–containing vacuole deviates from the canonical endocytic pathway immediately after a unique caveolae-dependent entry pathway, thus avoiding delivery into lysosomes. In contrast, in macrophages, C. jejuni is delivered to lysosomes and consequently is rapidly killed. Taken together, these studies indicate that C. jejuni has evolved specific adaptations to survive within host cells. Campylobacter jejuni is one of the most common causes of food-borne illness in the United States and a major cause of diarrheal disease throughout the world. After infection through the oral route, this bacterium invades the cells of the intestinal epithelium, a property that is important for its ability to cause disease. Usually, bacteria and other material entering the cell move to compartments called lysosomes, where an acidic mix of enzymes breaks it down. This study shows that C. jejuni can survive within intestinal epithelial cells by avoiding delivery to lysosomes. In contrast, in macrophages, which are specialized cells with the capacity to engulf and kill bacteria, C. jejuni cannot avoid delivery into lysosomes and consequently is rapidly killed. These studies help explain an important virulence attribute of C. jejuni.
Collapse
Affiliation(s)
- Robert O Watson
- Section of Microbial Pathogenesis, Yale University, School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E Galán
- Section of Microbial Pathogenesis, Yale University, School of Medicine, New Haven, Connecticut, United States of America
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
49
|
Spanò S, Ugalde JE, Galán JE. Delivery of a Salmonella Typhi Exotoxin from a Host Intracellular Compartment. Cell Host Microbe 2008; 3:30-8. [DOI: 10.1016/j.chom.2007.11.001] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 08/19/2007] [Accepted: 11/01/2007] [Indexed: 11/29/2022]
|
50
|
Affiliation(s)
- Jorge E Galán
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| |
Collapse
|