201
|
Reissinger A, Skinner JA, Yuk MH. Downregulation of mitogen-activated protein kinases by the Bordetella bronchiseptica Type III secretion system leads to attenuated nonclassical macrophage activation. Infect Immun 2005; 73:308-16. [PMID: 15618167 PMCID: PMC538969 DOI: 10.1128/iai.73.1.308-316.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella bronchiseptica utilizes a type III secretion system (TTSS) to establish a persistent infection of the murine respiratory tract. Previous studies have shown that the Bordetella TTSS mediated cytotoxicity in different cell types, inhibition of NF-kappaB in epithelial cells, and differentiation of dendritic cells into a semimature state. Here we demonstrate modulation of mitogen-activated protein kinase (MAPK) signaling pathways and altered cytokine production in macrophages and dendritic cells by the Bordetella TTSS. In macrophages, the MAPKs ERK and p38 were downregulated. This resulted in attenuated production of interleukin- (IL-)6 and IL-10. In contrast, the Th-1-polarizing cytokine IL-12 was produced at very low levels and remained unmodulated by the Bordetella TTSS. In dendritic cells, ERK was transiently activated, but this failed to alter cytokine profiles. These results suggest that the Bordetella TTSS modulates antigen-presenting cells in a cell type-specific manner and the secretion of high levels of IL-6 and IL-10 by macrophages might be important for pathogen clearance.
Collapse
Affiliation(s)
- Annette Reissinger
- Department of Microbiology, University of Pennsylvania School of Medicine, 201C Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104-6084, USA
| | | | | |
Collapse
|
202
|
Unsworth KE, Way M, McNiven M, Machesky L, Holden DW. Analysis of the mechanisms of Salmonella-induced actin assembly during invasion of host cells and intracellular replication. Cell Microbiol 2004; 6:1041-55. [PMID: 15469433 DOI: 10.1111/j.1462-5822.2004.00417.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Salmonella enterica serovar Typhimurium (S. typhimurium) induces actin assembly both during invasion of host cells and during the course of intracellular bacterial replication. In this study, we investigated the involvement in these processes of host cell signalling pathways that are frequently utilized by bacterial pathogens to manipulate the eukaryotic actin cytoskeleton. We confirmed that Cdc42, Rac, and Arp3 are involved in S. typhimurium invasion of HeLa cells, and found that N-WASP and Scar/WAVE also play a role in this process. However, we found no evidence for the involvement of these proteins in actin assembly during intracellular replication. Cortactin was recruited by Salmonella during both invasion and intracellular replication. However, RNA interference directed against cortactin did not inhibit either invasion or intracellular actin assembly, although it resulted in increased cell spreading and a greater number of lamellipodia. We also found no role for either the GTPase dynamin or the formin family member mDia1 in actin assembly by intracellular bacteria. Collectively, these data provide evidence that signalling pathways leading to Arp2/3-dependent actin nucleation play an important role in S. typhimurium invasion, but are not involved in intracellular Salmonella-induced actin assembly, and suggest that actin assembly by intracellular S. typhimurium may proceed by a novel mechanism.
Collapse
Affiliation(s)
- Kate E Unsworth
- Centre for Molecular Microbiology and Infection, Department of Infectious Diseases, Imperial College London, Armstrong Road, London SW7 2AZ, UK
| | | | | | | | | |
Collapse
|
203
|
Rottner K, Lommel S, Wehland J, Stradal TEB. Pathogen-induced actin filament rearrangement in infectious diseases. J Pathol 2004; 204:396-406. [PMID: 15495265 DOI: 10.1002/path.1638] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Host defence mechanisms involve the establishment and maintenance of numerous barriers to infectious microbes, including skin and mucosal surfaces, connective tissues, and a sophisticated immune system to detect and destroy invaders. Defeating these defence mechanisms and breaching the cell membrane barrier is the ultimate challenge for most pathogens. By invading the host and, moreover, by penetrating into individual host cells, pathogens gain access to a protective niche, not only to avoid immune clearance, but also to replicate and to disseminate from cell to cell within the infected host. Many pathogens are accomplishing these challenges by exploiting the actin cytoskeleton in a highly sophisticated manner as a result of having evolved common as well as unique strategies.
Collapse
Affiliation(s)
- Klemens Rottner
- Cytoskeleton Dynamics Group, German Research Centre for Biotechnology (GBF), Mascheroder Weg 1, D-38124 Braunschweig, Germany
| | | | | | | |
Collapse
|
204
|
Abstract
Salmonella strains utilize a type III secretion system for their successful survival and replications inside host cells. SseF is one of the several effector proteins that are required for conferring this survival ability by altering the trafficking of the Salmonella-containing vacuoles. These effector proteins often require appropriate chaperones to maintain their stabilities inside the bacteria. These chaperones are also known to assist the subsequent secretion and translocation of their substrates. We report here that SscB acts as the chaperone for SseF, an effector for the Salmonella pathogenicity island 2 (SPI-2). We found that the sscB gene is required for the formation of Salmonella sp.-induced continuous filaments in epithelial cells. Efficient Salmonella replication in macrophages requires SscB function. Intracellular and secretion levels of SseF are greatly reduced in an sscB mutant strain compared to the wild-type strain. A protein stability assay demonstrated that the half-life of SseF is significantly shortened in the absence of SscB. Transcriptional analysis of the sseF gene showed that the effect of SscB on the SseF level is not at the transcriptional level. A coprecipitation experiment indicated that SscB interacts with SseF. In summary, our results indicate that SscB is a chaperone for SPI-2 effector SseF to facilitate its secretion and function inside the host cells.
Collapse
Affiliation(s)
- Shipan Dai
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | |
Collapse
|
205
|
Dai S, Sarmiere PD, Wiggan O, Bamburg JR, Zhou D. Efficient Salmonella entry requires activity cycles of host ADF and cofilin. Cell Microbiol 2004; 6:459-71. [PMID: 15056216 DOI: 10.1111/j.1462-5822.2004.00375.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Entry of Salmonella into mammalian cells is strictly dependent on the reorganization of actin cytoskeleton induced by a panel of Salmonella type III secreted proteins. Although several factors have been identified to be responsible for inducing the actin polymerization and stability, little is known about how the actin depolymerization contributes to Salmonella-induced actin rearrangements. We report here that activity cycles of host actin depolymerizing factor (ADF and cofilin) are modulated by Salmonella during bacterial entry. Efficient Salmonella internalization involves an initial dephosphorylation of ADF and cofilin followed by phosphorylation, suggesting that ADF and cofilin activities are increased briefly. Expression of a kinase dead form of an ADF/cofilin kinase (LIM kinase 1) or a catalytically inactive ADF/cofilin phosphatase (Slingshot), but not constitutively active LIM kinase 1 or wild-type Slingshot, resulted in decreased invasion. These data suggest that ADF/cofilin activities play a key role in the actin polymerization/depolymerization process induced by Salmonella. The activation of ADF/cofilin is brief and has to be reversed to facilitate efficient bacterial entry. Surprisingly, co-expression of constitutive active ADF and cofilin prevented efficient Salmonella entry, whereas expression of either one alone had no effect. We propose that ADF and cofilin actin-dynamizing activities and their activity cycling via phosphorylation are required for efficient Salmonella internalization.
Collapse
Affiliation(s)
- Shipan Dai
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | | | | | | | |
Collapse
|
206
|
Abstract
Some bacterial pathogens enter mammalian cells by injecting, directly into the host cytosol, proteins that trigger cytoskeletal rearrangements necessary for internalization. In the February 27 issue of Molecular Cell, McGhie et al. identify mechanisms by which the Salmonella protein SipA interferes with ADF/cofilin and gelsolin function. Thus Salmonella not only triggers actin polymerization but also counteracts the major F-actin destabilizing proteins.
Collapse
Affiliation(s)
- Pascale Cossart
- Unité des Interactions Bactéries Cellules, Institut Pasteur, 28 Rue du Docteur Roux, INSERM U604, Paris 75015, France
| |
Collapse
|
207
|
Vicente-Manzanares M, Sánchez-Madrid F. Role of the cytoskeleton during leukocyte responses. Nat Rev Immunol 2004; 4:110-22. [PMID: 15040584 DOI: 10.1038/nri1268] [Citation(s) in RCA: 272] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The cytoskeleton is a cellular network of structural, adaptor and signalling molecules that regulates most cellular functions that are related to the immune response, including migration, extravasation, antien recognition, activation and phagocytosis by different subsets of leukocytes. Recently, a large number of regulatory elements and structural constituents of the leukocyte cytoskeleton have been identified. In this review, we discuss the composition and regulation of the different cytoskeletal elements and their role in immune responses.
Collapse
Affiliation(s)
- Miguel Vicente-Manzanares
- Servicio de Inmunología, Hospital Universitario de la Princesa, c/Diego de León 62, 28006-Madrid, Spain
| | | |
Collapse
|
208
|
McGhie EJ, Hayward RD, Koronakis V. Control of actin turnover by a salmonella invasion protein. Mol Cell 2004; 13:497-510. [PMID: 14992720 DOI: 10.1016/s1097-2765(04)00053-x] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Revised: 12/12/2003] [Accepted: 12/12/2003] [Indexed: 10/26/2022]
Abstract
Salmonella force their way into nonphagocytic host intestinal cells to initiate infection. Uptake is triggered by delivery into the target cell of bacterial effector proteins that stimulate cytoskeletal rearrangements and membrane ruffling. The Salmonella invasion protein A (SipA) effector is an actin binding protein that enhances uptake efficiency by promoting actin polymerization. SipA-bound actin filaments (F-actin) are also resistant to artificial disassembly in vitro. Using biochemical assays of actin dynamics and actin-based motility models, we demonstrate that SipA directly arrests cellular mechanisms of actin turnover. SipA inhibits ADF/cofilin-directed depolymerization both by preventing binding of ADF and cofilin and by displacing them from F-actin. SipA also protects F-actin from gelsolin-directed severing and reanneals gelsolin-severed F-actin fragments. These data suggest that SipA focuses host cytoskeletal reorganization by locally inhibiting both ADF/cofilin- and gelsolin-directed actin disassembly, while simultaneously stimulating pathogen-induced actin polymerization.
Collapse
Affiliation(s)
- Emma J McGhie
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom
| | | | | |
Collapse
|
209
|
Catron DM, Lange Y, Borensztajn J, Sylvester MD, Jones BD, Haldar K. Salmonella enterica serovar Typhimurium requires nonsterol precursors of the cholesterol biosynthetic pathway for intracellular proliferation. Infect Immun 2004; 72:1036-42. [PMID: 14742551 PMCID: PMC321618 DOI: 10.1128/iai.72.2.1036-1042.2004] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We have previously shown that Salmonella enterica serovar Typhimurium infection perturbs the host cholesterol biosynthetic pathway. Here we show that inhibiting the first step of this pathway (3-hydroxy-3-methylglutaryl coenzyme A reductase) reduces the growth of intracellular S. enterica serovar Typhimurium and has no effect on extracellular bacterial growth. Selectively inhibiting synthesis of downstream sterol components has no effect on infection, suggesting that the effect of statins on host nonsterol intermediates is detrimental to bacterial growth. Furthermore, statins also reduce bacterial proliferation in the S. enterica serovar Typhimurium mouse model. This suggests that blocking the production of nonsterol precursors in the host cell can be used to reduce infection.
Collapse
Affiliation(s)
- Drew M Catron
- Departments of Pathology and Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | | | | | | | | | | |
Collapse
|
210
|
Hapfelmeier S, Ehrbar K, Stecher B, Barthel M, Kremer M, Hardt WD. Role of the Salmonella pathogenicity island 1 effector proteins SipA, SopB, SopE, and SopE2 in Salmonella enterica subspecies 1 serovar Typhimurium colitis in streptomycin-pretreated mice. Infect Immun 2004; 72:795-809. [PMID: 14742523 PMCID: PMC321604 DOI: 10.1128/iai.72.2.795-809.2004] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Salmonella enterica subspecies 1 serovar Typhimurium (serovar Typhimurium) induces enterocolitis in humans and cattle. The mechanisms of enteric salmonellosis have been studied most extensively in calf infection models. The previous studies established that effector protein translocation into host cells via the Salmonella pathogenicity island 1 (SPI-1) type III secretion system (TTSS) is of central importance in serovar Typhimurium enterocolitis. We recently found that orally streptomycin-pretreated mice provide an alternative model for serovar Typhimurium colitis. In this model the SPI-1 TTSS also plays a key role in the elicitation of intestinal inflammation. However, whether intestinal inflammation in calves and intestinal inflammation in streptomycin-pretreated mice are induced by the same SPI-1 effector proteins is still unclear. Therefore, we analyzed the role of the SPI-1 effector proteins SopB/SigD, SopE, SopE2, and SipA/SspA in elicitation of intestinal inflammation in the murine model. We found that sipA, sopE, and, to a lesser degree, sopE2 contribute to murine colitis, but we could not assign an inflammation phenotype to sopB. These findings are in line with previous studies performed with orally infected calves. Extending these observations, we demonstrated that in addition to SipA, SopE and SopE2 can induce intestinal inflammation independent of each other and in the absence of SopB. In conclusion, our data corroborate the finding that streptomycin-pretreated mice provide a useful model for studying the molecular mechanisms of serovar Typhimurium colitis and are an important starting point for analysis of the molecular events triggered by SopE, SopE2, and SipA in vivo.
Collapse
|
211
|
Hernandez LD, Pypaert M, Flavell RA, Galán JE. A Salmonella protein causes macrophage cell death by inducing autophagy. ACTA ACUST UNITED AC 2004; 163:1123-31. [PMID: 14662750 PMCID: PMC2173598 DOI: 10.1083/jcb.200309161] [Citation(s) in RCA: 171] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Salmonella enterica, the causative agent of food poisoning and typhoid fever, induces programmed cell death in macrophages, a process found to be dependent on a type III protein secretion system, and SipB, a protein with membrane fusion activity that is delivered into host cells by this system. When expressed in cultured cells, SipB caused the formation of and localized to unusual multimembrane structures. These structures resembled autophagosomes and contained both mitochondrial and endoplasmic reticulum markers. A mutant form of SipB devoid of membrane fusion activity localized to mitochondria, but did not induce the formation of membrane structures. Upon Salmonella infection of macrophages, SipB was found in mitochondria, which appeared swollen and devoid of christae. Salmonella-infected macrophages exhibited marked accumulation of autophagic vesicles. We propose that Salmonella, through the action of SipB, kills macrophages by disrupting mitochondria, thereby inducing autophagy and cell death.
Collapse
Affiliation(s)
- Lorraine D Hernandez
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | | | | | | |
Collapse
|
212
|
Ehrbar K, Friebel A, Miller SI, Hardt WD. Role of the Salmonella pathogenicity island 1 (SPI-1) protein InvB in type III secretion of SopE and SopE2, two Salmonella effector proteins encoded outside of SPI-1. J Bacteriol 2004; 185:6950-67. [PMID: 14617659 PMCID: PMC262699 DOI: 10.1128/jb.185.23.6950-6967.2003] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica subspecies 1 serovar Typhimurium encodes a type III secretion system (TTSS) within Salmonella pathogenicity island 1 (SPI-1). This TTSS injects effector proteins into host cells to trigger invasion and inflammatory responses. Effector proteins are recognized by the TTSS via signals encoded in their N termini. Specific chaperones can be involved in this process. The chaperones InvB, SicA, and SicP are encoded in SPI-1 and are required for transport of SPI-1-encoded effectors. Several key effector proteins, like SopE and SopE2, are located outside of SPI-1 but are secreted in an SPI-1-dependent manner. It has not been clear how these effector proteins are recognized by the SPI-1 TTSS. Using pull-down and coimmunoprecipitation assays, we found that SopE is copurified with InvB, the known chaperone for the SPI-1-encoded effector protein Sip/SspA. We also found that InvB is required for secretion and translocation of SopE and SopE2 and for stabilization of SopE2 in the bacterial cytosol. Our data demonstrate that effector proteins encoded within and outside of SPI-1 use the same chaperone for secretion via the SPI-1 TTSS.
Collapse
Affiliation(s)
- Kristin Ehrbar
- Institute of Microbiology, D-BIOL, ETH Zürich, 8092 Zürich, Switzerland
| | | | | | | |
Collapse
|
213
|
Yoon H, Lim S, Heu S, Choi S, Ryu S. Proteome analysis of Salmonella enterica serovar Typhimurium fis mutant. FEMS Microbiol Lett 2003; 226:391-6. [PMID: 14553938 DOI: 10.1016/s0378-1097(03)00641-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is an enteric pathogen and a principal cause of gastroenteritis in humans. The factor-for-inversion stimulation protein (Fis) is known to play a pivotal role in the expression of Salmonella pathogenicity island (SPI)-1 genes in addition to various cellular processes such as recombination, replication, and transcription. In order to understand Fis function in pathogenicity of Salmonella, we performed two-dimensional gel electrophoresis and identified proteins whose expression pattern is affected by Fis using mass spectrometry. The results revealed various proteins that can be grouped according to their respective cellular functions. These groups include the genes involved in the metabolism of sugar, flagella synthesis, translation, and SPI expression. Changes in SPI expression suggest the possibility that regulation of genes in SPI-2 as well as SPI-1 is affected by Fis.
Collapse
Affiliation(s)
- Hyunjin Yoon
- Department of Food Science and Technology, School of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University, Seoul 151-742, South Korea
| | | | | | | | | |
Collapse
|
214
|
Hurley BP, McCormick BA. Translating tissue culture results into animal models: the case of Salmonella typhimurium. Trends Microbiol 2003; 11:562-9. [PMID: 14659688 DOI: 10.1016/j.tim.2003.10.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Investigators use both in vitro and in vivo models to better understand infectious disease processes. Both models are extremely useful in research, but there exists a significant gap in complexity between the highly controlled reductionist in vitro systems and the largely undefined, but relevant variability encompassing in vivo animal models. In an effort to understand how Salmonella initiates disease at the intestinal epithelium, in vitro models have served a useful purpose in allowing investigators to identify molecular mechanisms responsible for Salmonella invasion of host cells and stimulation of host inflammatory responses. Identification of these molecular mechanisms has generated hypotheses that are now being tested using in vivo models. Translating the in vitro findings into the context of an animal model and subsequently to human disease remains a difficult challenge for any disease process.
Collapse
Affiliation(s)
- Bryan P Hurley
- Combined Program in Pediatric Gastroenterology and Nutrition, Massachusetts General Hospital, 114 16th Street (114-3503), Charlestown, MA 02129, USA
| | | |
Collapse
|
215
|
Parikh SS, Litherland SA, Clare-Salzler MJ, Li W, Gulig PA, Southwick FS. CapG(-/-) mice have specific host defense defects that render them more susceptible than CapG(+/+) mice to Listeria monocytogenes infection but not to Salmonella enterica serovar Typhimurium infection. Infect Immun 2003; 71:6582-90. [PMID: 14573680 PMCID: PMC219612 DOI: 10.1128/iai.71.11.6582-6590.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Loss of the actin filament capping protein CapG has no apparent effect on the phenotype of mice maintained under sterile conditions; however, bone marrow-derived macrophages from CapG(-/-) mice exhibited distinct motility defects. We examined the ability of CapG(-/-) mice to clear two intracellular bacteria, Listeria monocytogenes and Salmonella enterica serovar Typhimurium. The 50% lethal dose of Listeria was 10-fold lower for CapG(-/-) mice than for CapG(+/+) mice (6 x 10(3) CFU for CapG(-/-) mice and 6 x 10(4) CFU for CapG(+/+) mice), while no difference was observed for Salmonella: The numbers of Listeria cells in the spleens and livers were significantly higher in CapG(-/-) mice than in CapG(+/+) mice at days 5 to 9, while the bacterial counts were identical on day 5 for Salmonella-infected mice. Microscopic analysis revealed qualitatively similar inflammatory responses in the spleens and livers of the two types of mice. Specific immunofluorescence staining analyzed by fluorescence-activated cell sorting revealed similar numbers of macrophages and dendritic cells in infected CapG(-/-) and CapG(+/+) spleens. However, analysis of bone marrow-derived macrophages revealed a 50% reduction in the rate of phagocytosis of Listeria in CapG(-/-) cells but a normal rate of phagocytosis of Salmonella: Stimulation of bone marrow-derived dendritic cells with granulocyte-macrophage colony-stimulating factor resulted in a reduction in the ruffling response of CapG(-/-) cells compared to the response of CapG(+/+) cells, and CapG(-/-) bone-marrowed derived neutrophils migrated at a mean speed that was nearly 50% lower than the mean speed of CapG(+/+) neutrophils. Our findings suggest that specific motility deficits in macrophages, dendritic cells, and neutrophils render CapG(-/-) mice more susceptible than CapG(+/+) mice to Listeria infection.
Collapse
Affiliation(s)
- Shefal S Parikh
- Department of Medicine, University of Florida College of Medicine, Gainesville, Florida 32610, USA
| | | | | | | | | | | |
Collapse
|
216
|
Abstract
HilA activates the transcription of genes on Salmonella pathogenicity island 1 (SPI1), which encodes a type III secretion system (TTSS). Previous studies showed that transposon insertions in orgC, a gene located on SPI1, increase hilA expression. We characterize the orgC gene product and show that it is secreted via the SPI1 TTSS. We propose a model whereby OrgC functions as a secreted repressor of the SPI1 virulence genes.
Collapse
Affiliation(s)
- James B Day
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
| | | |
Collapse
|
217
|
La Ragione RM, Cooley WA, Velge P, Jepson MA, Woodward MJ. Membrane ruffling and invasion of human and avian cell lines is reduced for aflagellate mutants of Salmonella enterica serotype Enteritidis. Int J Med Microbiol 2003; 293:261-72. [PMID: 14503791 DOI: 10.1078/1438-4221-00263] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Independent studies have demonstrated that flagella are associated with the invasive process of Salmonella enterica serotypes, and aflagellate derivatives of Salmonella enterica serotype Enteritidis are attenuated in murine and avian models of infection. One widely held view is that the motility afforded by flagella, probably aided by chemotactic responses, mediates the initial interaction between bacterium and host cell. The adherence and invasion properties of two S. Enteritidis wild-type strains and isogenic aflagellate mutants were assessed on HEp-2 and Div-1 cells that are of human and avian epithelial origin, respectively. Both aflagellate derivatives showed a significant reduction of invasion compared with wild type over the three hours of the assays. Complementation of the defective fliC allele recovered partially the wild-type phenotype. Examination of the bacterium-host cell interaction by electron and confocal microscopy approaches showed that wild-type bacteria induced ruffle formation and significant cytoskeletal rearrangements on HEp-2 cells within 5 minutes of contact. The aflagellate derivatives induced fewer ruffles than wild type. Ruffle formation on the Div-1 cell line was less pronounced than for HEp-2 cells for wild-type S. Enteritidis. Collectively, these data support the hypothesis that flagella play an active role in the early events of the invasive process.
Collapse
Affiliation(s)
- Roberto M La Ragione
- Department of Bacterial Diseases, Veterinary Laboratories Agency, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | | | | | | | | |
Collapse
|
218
|
Lilic M, Galkin VE, Orlova A, VanLoock MS, Egelman EH, Stebbins CE. Salmonella SipA polymerizes actin by stapling filaments with nonglobular protein arms. Science 2003; 301:1918-21. [PMID: 14512630 DOI: 10.1126/science.1088433] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Like many bacterial pathogens, Salmonella spp. use a type III secretion system to inject virulence proteins into host cells. The Salmonella invasion protein A (SipA) binds host actin, enhances its polymerization near adherent extracellular bacteria, and contributes to cytoskeletal rearrangements that internalize the pathogen. By combining x-ray crystallography of SipA with electron microscopy and image analysis of SipA-actin filaments, we show that SipA functions as a "molecular staple," in which a globular domain and two nonglobular "arms" mechanically stabilize the filament by tethering actin subunits in opposing strands. Deletion analysis of the tethering arms provides strong support for this model.
Collapse
Affiliation(s)
- Mirjana Lilic
- Laboratory of Structural Microbiology, Rockefeller University, New York, NY 10021, USA
| | | | | | | | | | | |
Collapse
|
219
|
de Andrade DR, de Andrade Júnior DR. Typhoid fever as cellular microbiological model. Rev Inst Med Trop Sao Paulo 2003; 45:185-91. [PMID: 14502344 DOI: 10.1590/s0036-46652003000400002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The knowledge about typhoid fever pathogenesis is growing in the last years, mainly about the cellular and molecular phenomena that are responsible by clinical manifestations of this disease. In this article are discussed several recent discoveries, as follows: a) Bacterial type III protein secretion system; b) The five virulence genes of Salmonella spp. that encoding Sips (Salmonella invasion protein) A, B, C, D and E, which are capable of induce apoptosis in macrophages; c) The function of Toll R2 and Toll R4 receptors present in the macrophage surface (discovered in the Drosophila). The Toll family receptors are critical in the signalizing mediated by LPS in macrophages in association with LBP and CD14; d) The lines of immune defense between intestinal lumen and internal organs; e) The fundamental role of the endothelial cells in the inflammatory deviation from bloodstream into infected tissues by bacteria. In addition to above subjects, the authors comment the correlation between the clinical features of typhoid fever and the cellular and molecular phenomena of this disease, as well as the therapeutic consequences of this knowledge.
Collapse
Affiliation(s)
- Dahir Ramos de Andrade
- Laboratório de Investigação Médica, School of Medicine, University of São Paulo, São Paulo, SP, Brazil.
| | | |
Collapse
|
220
|
Zhang S, Adams LG, Nunes J, Khare S, Tsolis RM, Bäumler AJ. Secreted effector proteins of Salmonella enterica serotype typhimurium elicit host-specific chemokine profiles in animal models of typhoid fever and enterocolitis. Infect Immun 2003; 71:4795-803. [PMID: 12874363 PMCID: PMC166006 DOI: 10.1128/iai.71.8.4795-4803.2003] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Infection of bovine ligated loops with the Salmonella enterica serotype Typhimurium wild type but not a sipA sopABDE2 mutant resulted in fluid accumulation, polymorphonuclear cell infiltration, and expression of CXC chemokines, particularly GRO alpha. None of these sipA sopABDE2-dependent responses was observed in murine-ligated loops. The majority of GRO alpha transcripts localized to bovine intestinal epithelium. Thus, different disease outcomes between mice (i.e., no diarrhea) and calves (i.e., diarrhea) may be due to differences in sipA sopABDE2-dependent CXC chemokine gene expression in epithelial cells.
Collapse
Affiliation(s)
- Shuping Zhang
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843-4467, USA
| | | | | | | | | | | |
Collapse
|
221
|
Gophna U, Ron EZ, Graur D. Bacterial type III secretion systems are ancient and evolved by multiple horizontal-transfer events. Gene 2003; 312:151-63. [PMID: 12909351 DOI: 10.1016/s0378-1119(03)00612-7] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Type III secretion systems (TTSS) are unique bacterial mechanisms that mediate elaborate interactions with their hosts. The fact that several of the TTSS proteins are closely related to flagellar export proteins has led to the suggestion that TTSS had evolved from flagella. Here we reconstruct the evolutionary history of four conserved type III secretion proteins and their phylogenetic relationships with flagellar paralogs. Our analysis indicates that the TTSS and the flagellar export mechanism share a common ancestor, but have evolved independently from one another. The suggestion that TTSS genes have evolved from genes encoding flagellar proteins is effectively refuted. A comparison of the species tree, as deduced from 16S rDNA sequences, to the protein phylogenetic trees has led to the identification of several major lateral transfer events involving clusters of TTSS genes. It is hypothesized that horizontal gene transfer has occurred much earlier and more frequently than previously inferred for TTSS genes and is, consequently, a major force shaping the evolution of species that harbor type III secretion systems.
Collapse
Affiliation(s)
- Uri Gophna
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel 69978.
| | | | | |
Collapse
|
222
|
Royle MCJ, Tötemeyer S, Alldridge LC, Maskell DJ, Bryant CE. Stimulation of Toll-like receptor 4 by lipopolysaccharide during cellular invasion by live Salmonella typhimurium is a critical but not exclusive event leading to macrophage responses. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:5445-54. [PMID: 12759420 DOI: 10.4049/jimmunol.170.11.5445] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Invasion of macrophages by salmonellae induces cellular responses, with the bacterial inducers likely to include a number of pathogen-associated molecular patterns. LPS is one of the prime candidates, but its precise role in the process, especially when presented as a component of live infecting bacteria, is unclear. We thus investigated this question using the lipid A antagonist E5531, the macrophage-like cell line RAW 264.7, and primary macrophage cultures from C3H/HeJ and Toll-like receptor 4(-/-) (TLR-4(-/-)) mice. We show that LPS presented on live salmonellae provides an essential signal, via functional TLR-4, for macrophages to produce NO and TNF-alpha. Furthermore, the mitogen-activated protein kinase c-Jun N-terminal kinase and p38 are activated, and the transcription factor NF-kappa B is translocated to the nucleus when RAW 264.7 cells are presented with purified LPS or live salmonellae. Purified LPS stimulates rapid, transitory mitogen-activated protein kinase activation that is inhibited by E5531, whereas bacterial invasion stimulates delayed, prolonged activation, unaffected by E5531. Both purified LPS and bacterial invasion caused translocation of NF-kappa B, but whereas E5531 always inhibited activation by purified LPS, activation by bacterial invasion was only inhibited at later time points. In conclusion, we show for the first time that production of NO and TNF-alpha is critically dependent on activation of TLR-4 by LPS during invasion of macrophages by salmonellae, but that different patterns of activation of intracellular signaling pathways are induced by purified LPS vs live salmonellae.
Collapse
Affiliation(s)
- Matthew C J Royle
- Department of Clinical Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | | | | | | | | |
Collapse
|
223
|
Abstract
Bacterial pathogens utilize several strategies to modulate the organization of the actin cytoskeleton. Some bacterial toxins catalyze the covalent modification of actin or the Rho GTPases, which are involved in the control of the actin cytoskeleton. Other bacteria produce toxins that act as guanine nucleotide exchange factors or GTPase-activating proteins to modulate the nucleotide state of the Rho GTPases. This latter group of toxins provides a temporal modulation of the actin cytoskeleton. A third group of bacterial toxins act as adenylate cyclases, which directly elevate intracellular cAMP to supra-physiological levels. Each class of toxins gives the bacterial pathogen a selective advantage in modulating host cell resistance to infection.
Collapse
Affiliation(s)
- Joseph T Barbieri
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee 53226, USA.
| | | | | |
Collapse
|
224
|
Kusner DJ, Barton JA, Qin C, Wang X, Iyer SS. Evolutionary conservation of physical and functional interactions between phospholipase D and actin. Arch Biochem Biophys 2003; 412:231-41. [PMID: 12667487 DOI: 10.1016/s0003-9861(03)00052-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Phospholipase D (PLD) enzymes from bacteria to mammals exhibit a highly conserved core structure and catalytic mechanism, but whether protein-protein interactions exhibit similar commonality is unknown. Our objective was to determine whether the physical and functional interactions of mammalian PLDs with actin are evolutionarily conserved among bacterial and plant PLDs. Highly purified bacterial and plant PLDs cosedimented with mammalian skeletal muscle alpha-actin, indicating direct interaction with F-actin. The binding of bacterial PLD to G-actin exhibited two affinity states, with dissociation constants of 1.13 pM and 0.58 microM. The effects of actin on the activities of bacterial and plant PLDs were polymerization dependent; monomeric G-actin inhibited PLD activity, whereas polymerized F-actin augmented PLD activity. Actin modulation of bacterial and plant PLDs demonstrated kinetic characteristics, efficacies, and potencies similar to those of human PLD1. Thus, physical and functional interactions between PLD and actin in PLD family members from bacteria to mammals are highly conserved throughout evolution.
Collapse
Affiliation(s)
- David J Kusner
- Department of Internal Medicine, University of Iowa Carrer College of Medicine and VA Medical Center, Iowa City, IA 52242, USA.
| | | | | | | | | |
Collapse
|
225
|
Miao EA, Brittnacher M, Haraga A, Jeng RL, Welch MD, Miller SI. Salmonella effectors translocated across the vacuolar membrane interact with the actin cytoskeleton. Mol Microbiol 2003; 48:401-15. [PMID: 12675800 DOI: 10.1046/j.1365-2958.2003.t01-1-03456.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A family of nine Salmonella typhimurium type III secretion effectors with a conserved amino-terminus have been defined. Three family members (SifA, SifB and SseJ) have previously been demonstrated to localize to the Salmonella-containing vacuole and to Salmonella-induced filaments. In contrast, we demonstrate that two other family members, SspH2 and SseI, co-localized with the polymerizing actin cytoskeleton. These proteins also interacted with the mammalian actin cross-linking protein filamin in the yeast two-hybrid assay through their highly conserved amino-terminal domains. This amino-terminus was sufficient to direct localization to the polymerizing actin cytoskeleton, suggesting that the interaction with filamin is important for this subcellular localization. In addition, SspH2 co-localized with vacuole-associated actin polymerizations (VAP) induced by intracellular bacteria through the Salmonella pathogenicity island (SPI)-2 type III secretion system (TTSS). SspH2 interacted with the actin-binding protein profilin in the yeast two-hybrid assay and by affinity chromatography. This interaction was highly specific to SspH2 and was mediated by its carboxy-terminus. Furthermore, SspH2 inhibited the rate of actin polymerization in vitro, suggesting that it functions to reduce or remodel VAP. Strains with mutations in sspH2 and sseI retained the ability to form VAP. However, a third intracellular virulence factor, spvB, which ADP-ribosylates actin, strongly inhibited VAP formation in HeLa cells, suggesting a more subtle effect for SspH2 and SseI on the actin cytoskeleton.
Collapse
Affiliation(s)
- Edward A Miao
- Department of Microbiology, University of Washington, HSB K-140, Box 357710, Seattle, WA 98195-7710, USA
| | | | | | | | | | | |
Collapse
|
226
|
Pasmans F, Van Immerseel F, Van den Broeck W, Bottreau E, Velge P, Ducatelle R, Haesebrouck F. Interactions of Salmonella enterica subsp. enterica serovar Muenchen with intestinal explants of the turtle Trachemys scripta scripta. J Comp Pathol 2003; 128:119-26. [PMID: 12634088 DOI: 10.1053/jcpa.2002.0614] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Salmonella infections in reptiles, in contrast to those in birds and mammals, are limited to the intestinal tract. In this study, interactions of a strain of Salmonella enterica subsp. enterica serovar Muenchen (SEEM) with intestinal explants of the turtle Trachemys scripta scripta were examined by scanning electron microscopy (SEM). Adhesion and invasion in the chelonian intestinal explants at 30 degrees C and 37 degrees C were evaluated quantitatively. For purposes of comparison, the invasive capacity of SEEM in the continuous avian epithelial cell line DIV-1 at 30 degrees C and 37 degrees C was determined. Small numbers of M-like cells were found in the ileum of the turtles. The bacteria adhered mainly to the mucus of the intestinal explants. Only small numbers of salmonellae were associated with epithelial cells. Higher numbers of bacteria adhered at 30 degrees C than at 37 degrees C. Epithelial damage, embedding of bacteria in the epithelial surface and a ruffling-like process were noted only at 37 degrees C. Minimal numbers of salmonellae invaded the explants at 30 degrees C and 37 degrees C. Invasion of DIV-1 cells was greater at 37 degrees C than at 30 degrees C. The study suggested that the intestinal mucous layer provides an important site of colonization for salmonellae in the chelonian host and protects the underlying epithelial cells.
Collapse
Affiliation(s)
- F Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | | | | | | | | | | | | |
Collapse
|
227
|
Köhler H, McCormick BA, Walker WA. Bacterial-enterocyte crosstalk: cellular mechanisms in health and disease. J Pediatr Gastroenterol Nutr 2003; 36:175-85. [PMID: 12548051 DOI: 10.1097/00005176-200302000-00005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Henrik Köhler
- Mucosal Immunology Laboratory, Combined Program in Pediatric Gastroenterology and Nutrition, Massachusetts General Hospital and Harvard Medical School, 114 16th Street, Charlestown, MA 02129, USA
| | | | | |
Collapse
|
228
|
Zhang S, Kingsley RA, Santos RL, Andrews-Polymenis H, Raffatellu M, Figueiredo J, Nunes J, Tsolis RM, Adams LG, Bäumler AJ. Molecular pathogenesis of Salmonella enterica serotype typhimurium-induced diarrhea. Infect Immun 2003; 71:1-12. [PMID: 12496143 PMCID: PMC143292 DOI: 10.1128/iai.71.1.1-12.2003] [Citation(s) in RCA: 211] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Shuping Zhang
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
229
|
Abstract
Infections with Salmonella serotypes are a major cause of food-borne diseases worldwide. Animal models other than the mouse have been employed for the study of nontyphoidal Salmonella infections because the murine model is not suitable for the study of Salmonella-induced diarrhea. The microbe has developed mechanisms to exploit the host cell machinery to its own purpose. Bacterial proteins delivered directly into the host cell cytosol cause cytoskeletal changes and interfere with host cell signaling pathways, which ultimately enhance disease manifestation. Recently, marked advances have been made in our understanding of the molecular interactions between Salmonella serotypes and their hosts. Here, we discuss the molecular basis of the pathogenesis of Salmonella-induced enteritis.
Collapse
Affiliation(s)
- R L Santos
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | | | | | | |
Collapse
|
230
|
Hobert ME, Sands KA, Mrsny RJ, Madara JL. Cdc42 and Rac1 regulate late events in Salmonella typhimurium-induced interleukin-8 secretion from polarized epithelial cells. J Biol Chem 2002; 277:51025-32. [PMID: 12381718 DOI: 10.1074/jbc.m210466200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Salmonella typhimurium colonization of the intestinal epithelium initiates biochemical cross-talk between pathogen and host that results in the secretion of chemokines, such as interleukin (IL)-8, that direct neutrophil migration to the site of infection. In nonpolarized cells, Rac1 and Cdc42 have been shown to regulate both bacterial invasion and signaling events leading to nuclear responses and IL-8 secretion. However, because the underlying actin cytoskeleton and the associated signaling machinery are distributed much differently in polarized epithelial cells, we used polarized Madin-Darby canine kidney monolayers to investigate the role of Rac1 and Cdc42 in S. typhimurium-induced pro-inflammatory responses in the more physiologically relevant polarized state. In Madin-Darby canine kidney monolayers expressing dominant-negative Rac1 or Cdc42, both Salmonella- and tumor necrosis factor alpha-induced activation of NFkappaB and mitogen-activated protein kinase signaling cascades proceeded normally, but IL-8 secretion was inhibited. We found that Rac1 and Cdc42 were not involved in early pro-inflammatory signaling events, as in nonpolarized cells, but rather regulated the basolateral exocytosis and secretion of IL-8. In contrast, dominant-negative Rac1 inhibited apical actin pedestal formation, indicating that pedestal formation and nuclear signaling for pro-inflammatory activation are not linked. These findings indicate that there are significant differences in the requirements of pathogen-induced host cell signaling pathways in polarized and nonpolarized cells.
Collapse
Affiliation(s)
- Michael E Hobert
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
| | | | | | | |
Collapse
|
231
|
Lawhon SD, Maurer R, Suyemoto M, Altier C. Intestinal short-chain fatty acids alter Salmonella typhimurium invasion gene expression and virulence through BarA/SirA. Mol Microbiol 2002; 46:1451-64. [PMID: 12453229 DOI: 10.1046/j.1365-2958.2002.03268.x] [Citation(s) in RCA: 315] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Salmonella typhimurium causes enteric and systemic disease by invading the intestinal epithelium of the distal ileum, a process requiring the invasion genes of Salmonella pathogenicity island 1 (SPI-1). BarA, a sensor kinase postulated to interact with the response regulator SirA, is required for the expression of SPI-1 invasion genes. We found, however, that a barA null mutation had little effect on virulence using the mouse model for septicaemia. This confounding result led us to seek environmental signals present in the distal ileum that might supplant the need for BarA. We found that acetate restored the expression of invasion genes in the barA mutant, but had no effect on a sirA mutant. Acetate had its effect only at a pH that allowed its accumulation within the bacterial cytoplasm and not with the deletion of ackA and pta, the two genes required to produce acetyl-phosphate. These results suggest that the rising concentration of acetate in the distal ileum provides a signal for invasion gene expression by the production of acetyl-phosphate in the bacterial cytoplasm, a pathway that bypasses barA. We also found that a Delta(ackA-pta) mutation alone had no effect on virulence but, in combination with Delta(barA), it increased the oral LD50 24-fold. Thus, the combined loss of the BarA- and acetate-dependent pathways is required to reduce virulence. Two other short-chain fatty acids (SCFA), propionate and butyrate, present in high concentrations in the caecum and colon, had effects opposite to those of acetate: neither restored invasion gene expression in the barA mutant, and both, in fact, reduced expression in the wild-type strain. Further, a combination of SCFAs found in the distal ileum restored invasion gene expression in the barA mutant, whereas colonic conditions failed to do so and also reduced expression in the wild-type strain. These results suggest that the concentration and composition of SCFAs in the distal ileum provide a signal for productive infection by Salmonella, whereas those of the large intestine inhibit invasion.
Collapse
Affiliation(s)
- Sara D Lawhon
- Department of Microbiology, Pathology and Parasitology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606, USA
| | | | | | | |
Collapse
|
232
|
Carlson SA, Casey TA, Wu MT, Hammes BD, Jones BD. A high-throughput genetic system for assessing the inhibition of proteins: identification of antibiotic resistance and virulence targets and their cognate inhibitors in Salmonella. Anal Biochem 2002; 310:72-83. [PMID: 12413476 DOI: 10.1016/s0003-2697(02)00251-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study describes the development of a high-throughput genetic system for producing oligopeptides that can be used to identify molecular interactions leading to inhibition of specific proteins. Using a pathogenic bacteria model, we screened a library of clones expressing intracellular oligopeptides in order to identify inhibitors of proteins involved in antibiotic resistance and virulence. This method involved transforming the pathogen with an oligopeptide-encoding plasmid library, constructed using polymerase chain reaction and an oligonucleotide template designed to produce random oligopeptides composed of 2-16 amino acids, and high-throughput screening for phenotype alterations in the pathogen. A subsequent complementation phase enabled the identification of the full-length bacterial protein inhibited by the oligopeptide. Using this method we were able to identify oligopeptides that inhibit virulence and/or drug resistance in Salmonella, Shigella, and Escherichia coli; specific virulence and/or drug resistance proteins of Salmonella, Shigella, and E. coli that are sensitive to inhibition; and putative oligopeptide-binding sites on the inhibited proteins. This system is versatile and can be extended to other pathogens for analogous studies and it can be modified for used in eukaryotic models for identifying protein interactions that can be targeted for inhibition. Additionally, this system can be used for identifying protein domains involved in any biomolecular interaction.
Collapse
Affiliation(s)
- Steve A Carlson
- Pre-harvest Food Safety and Enteric Disease Research Unit, National Animal Disease Center, Agricultural Research Service/USDA, 2300 Dayton Road, Box 70, Ames, IA 50010, USA.
| | | | | | | | | |
Collapse
|
233
|
Delahay RM, Frankel G. Coiled-coil proteins associated with type III secretion systems: a versatile domain revisited. Mol Microbiol 2002; 45:905-16. [PMID: 12180912 DOI: 10.1046/j.1365-2958.2002.03083.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The pathogenic potential of many Gram-negative bacteria is indicated by the possession of a specialized type III secretion system that is used to deliver virulence effector proteins directly into the cellular environment of the eukaryotic host. Extracellular assemblies of secreted proteins contrive a physical link between the pathogen and host cytosol and enable the translocated effectors to bypass the bacterial and host membranes in a single step. Subsequent interactions of some effector proteins with host cytoskeletal and signalling proteins result in modulation of the cytoskeletal architecture of the aggressed cell and facilitate entry, survival and dissemination of the pathogen. Although the secreted components of type III secretion systems are diverse, many are predicted to share a common coiled-coil structural feature. Coiled-coils are ubiquitous and highly versatile assembly motifs found in a wide range of structural and regulatory proteins. The prevalence of these domains in secreted virulence effector proteins suggests a fundamental contribution to multiple aspects of their function, and evidence accumulating from functional studies suggests an intrinsic involvement of coiled-coils in subunit assembly, translocation and flexible interactions with multiple bacterial and host proteins. The known functional flexibility that coiled-coil domains confer upon proteins provides insights into some of the pathogenic mechanisms used during interaction with the host.
Collapse
Affiliation(s)
- Robin M Delahay
- Centre for Molecular Microbiology and Infection, Department of Biological Sciences, Imperial College of Science, Technology and Medicine, London, UK.
| | | |
Collapse
|
234
|
Carabeo RA, Grieshaber SS, Fischer E, Hackstadt T. Chlamydia trachomatis induces remodeling of the actin cytoskeleton during attachment and entry into HeLa cells. Infect Immun 2002; 70:3793-803. [PMID: 12065523 PMCID: PMC128046 DOI: 10.1128/iai.70.7.3793-3803.2002] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
To elucidate the host cell machinery utilized by Chlamydia trachomatis to invade epithelial cells, we examined the role of the actin cytoskeleton in the internalization of chlamydial elementary bodies (EBs). Treatment of HeLa cells with cytochalasin D markedly inhibited the internalization of C. trachomatis serovar L2 and D EBs. Association of EBs with HeLa cells induced localized actin polymerization at the site of attachment, as visualized by either phalloidin staining of fixed cells or the active recruitment of GFP-actin in viable infected cells. The recruitment of actin to the specific site of attachment was accompanied by dramatic changes in the morphology of cell surface microvilli. Ultrastructural studies revealed a transient microvillar hypertrophy that was dependent upon C. trachomatis attachment, mediated by structural components on the EBs, and cytochalasin D sensitive. In addition, a mutant CHO cell line that does not support entry of C. trachomatis serovar L2 did not display such microvillar hypertrophy following exposure to L2 EBs, which is in contrast to infection with serovar D, to which it is susceptible. We propose that C. trachomatis entry is facilitated by an active actin remodeling process that is induced by the attachment of this pathogen, resulting in distinct microvillar reorganization throughout the cell surface and the formation of a pedestal-like structure at the immediate site of attachment and entry.
Collapse
Affiliation(s)
- Reynaldo A Carabeo
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA
| | | | | | | |
Collapse
|
235
|
Zhang S, Santos RL, Tsolis RM, Stender S, Hardt WD, Bäumler AJ, Adams LG. The Salmonella enterica serotype typhimurium effector proteins SipA, SopA, SopB, SopD, and SopE2 act in concert to induce diarrhea in calves. Infect Immun 2002; 70:3843-55. [PMID: 12065528 PMCID: PMC128071 DOI: 10.1128/iai.70.7.3843-3855.2002] [Citation(s) in RCA: 222] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Salmonella enterica serotype Typhimurium requires a functional type III secretion system encoded by Salmonella pathogenicity island 1 (SPI1) to cause diarrhea. We investigated the role of genes encoding secreted target proteins of the SPI1-associated type III secretion system for enteropathogenicity in calves. Salmonella serotype Typhimurium strains having mutations in sptP, avrA, sspH1, or slrP induced fluid secretion in the bovine ligated ileal loop model at levels similar to that of the wild type. In contrast, mutations in sipA, sopA, sopB, sopD, or sopE2 significantly reduced fluid accumulation in bovine ligated ileal loops at 8 h postinfection. A strain carrying mutations in sipA, sopA, sopB, sopD, and sopE2 (sipA sopABDE2 mutant) caused the same level of fluid accumulation in bovine ligated ileal loops as a strain carrying a mutation in sipB, a SPI1 gene required for the translocation of effector proteins into host cells. A positive correlation was observed between the severity of histopathological lesions detected in the ileal mucosa and the levels of fluid accumulation induced by the different mutants. After oral infection of calves, the Salmonella serotype Typhimurium sipAsopABDE2 mutant caused only mild diarrhea and was more strongly attenuated than strains having only single mutations. These data demonstrate that SipA, SopA, SopB, SopD, and SopE2 are major virulence factors responsible for diarrhea during Salmonella serotype Typhimurium infection of calves.
Collapse
Affiliation(s)
- Shuping Zhang
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843-4467, USA
| | | | | | | | | | | | | |
Collapse
|
236
|
Catron DM, Sylvester MD, Lange Y, Kadekoppala M, Jones BD, Monack DM, Falkow S, Haldar K. The Salmonella-containing vacuole is a major site of intracellular cholesterol accumulation and recruits the GPI-anchored protein CD55. Cell Microbiol 2002; 4:315-28. [PMID: 12067317 DOI: 10.1046/j.1462-5822.2002.00198.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Intracellular, pathogenic Salmonella typhimurium avoids phago-lysosome fusion, and exists within a unique vacuolar niche that resembles a late endosome. This model has emerged from studying the trafficking of host proteins to the Salmonella-containing vacuole (SCV). Very little is known about the role of major host lipids during infection. Here, we show using biochemical analyses as well as fluorescence microscopy, that intracellular infection perturbs the host sterol biosynthetic pathway and induces cholesterol accumulation in the SCV. Cholesterol accumulation is seen in both macrophages and epithelial cells: at the terminal stages of infection, as much as 30% of the total cellular cholesterol resides in the SCV. We find that accumulation of cholesterol in the SCV is linked to intracellular bacterial replication and may be dependent on Salmonella pathogenicity island 2 (SPI-2). Furthermore, the construction of a three-dimensional space-filling model yields novel insights into the structure of the SCV: bacteria embedded in cholesterol-rich membranes. Finally, we show that the glycosylphosphatidylinositol (GPI)-anchored protein CD55 is recruited to the SCV. These data suggest that, in contrast to prevailing models, the SCV accumulates components of cholesterol-rich early endocytic pathways during intracellular bacterial replication.
Collapse
Affiliation(s)
- Drew M Catron
- Departments of Pathology and Microbiology-Immunology, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL 60611, USA
| | | | | | | | | | | | | | | |
Collapse
|
237
|
Higashide W, Dai S, Hombs VP, Zhou D. Involvement of SipA in modulating actin dynamics during Salmonella invasion into cultured epithelial cells. Cell Microbiol 2002; 4:357-65. [PMID: 12116966 DOI: 10.1046/j.1462-5822.2002.00196.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Salmonella entry into epithelial host cells results from the host actin cytoskeleton reorganization that is induced by a group of bacterial proteins delivered to the host cells by the Salmonella type III secretion system. SopE, SopE2 and SopB activate CDC42 and Rac1 to intercept the signal transduction pathways involved in actin cytoskeleton rearrangements. SipA and SipC directly bind actin to modulate the actin dynamics facilitating bacterial entry. Biochemical studies have indicated that SipA decreases the critical concentration for actin polymerization and may be involved in promoting the initial actin polymerization in Salmonella-induced actin reorganization. In this report, we conducted experiments to analyze the in vivo function(s) of SipA during Salmonella invasion. SipA was found to be preferentially associated with peripheral cortical actin filaments but not stress fibres using permeabilized epithelial cells. When polarized Caco-2 cells were infected with Salmonella, actin cytoskeleton rearrangements induced by the wild-type strain had many filopodia structures that were intimately associated with the bacteria. In contrast, ruffles induced by the sipA null mutant were smoother and distant from the bacteria. We also found that the F-actin content in cells infected with the sipA mutant decreased nearly 80% as compared to uninfected cells or those infected with the wild-type Salmonella strain. Furthermore, expression of either the full-length or the SipA(459-684) actin-binding fragment induced prominent punctuate actin assembly in the cortical region of COS-1 cells. These results indicate that SipA is involved in modulating actin dynamics in cultured epithelial cells during Salmonella invasion.
Collapse
Affiliation(s)
- Wendy Higashide
- Deparment of Biological Sciences, Purdue University, West Lafayette, IN 4790, USA
| | | | | | | |
Collapse
|
238
|
Scott CC, Cuellar-Mata P, Matsuo T, Davidson HW, Grinstein S. Role of 3-phosphoinositides in the maturation of Salmonella-containing vacuoles within host cells. J Biol Chem 2002; 277:12770-6. [PMID: 11821391 DOI: 10.1074/jbc.m110399200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Salmonella typhimurium invades mammalian cells and replicates within a vacuole that protects it from the host's microbicidal weapons. The Salmonella-containing vacuole (SCV) undergoes a remodelling akin to that of the host cell's endocytic pathway, but SCV progression is arrested prior to fusion with lysosomes. We studied the role of phosphatidylinositol 3-kinase (PI3-K) in SCV maturation within HeLa cells. Phosphatidylinositol 3-phosphate (PI3P), monitored in situ using fluorescent conjugates of FYVE or PX domains, was found to accumulate transiently on the SCV. Wortmannin prevented PI3P accumulation and the recruitment of EEA1 but did not affect the association of Rab5 with the SCV. Importantly, inhibition of PI3-K also impaired fusion of the SCV with vesicles containing LAMP-1. Rab7, which is thought to be required for association of LAMP-1 with the SCV, still associated with SCV in wortmannin-treated cells. We have therefore concluded that a 3-phosphoinositide-dependent step exists following recruitment of Rab7 to the SCV. The data also imply that 3-phosphoinositide-dependent effectors of Rab5 are not an absolute requirement for recruitment of Rab7. Despite failure to acquire LAMP-1, the SCV persists and allows effective replication of Salmonella within wortmannin-treated host cells. These findings imply that PI3-K is involved in the development of the SCV but is not essential for intracellular survival and proliferation of Salmonella.
Collapse
Affiliation(s)
- Cameron C Scott
- Division of Cell Biology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
| | | | | | | | | |
Collapse
|
239
|
Zaharik ML, Gruenheid S, Perrin AJ, Finlay BB. Delivery of dangerous goods: type III secretion in enteric pathogens. Int J Med Microbiol 2002; 291:593-603. [PMID: 12008913 DOI: 10.1078/1438-4221-00179] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Type III secretion systems (TTSSs) of Gram-negative pathogens are molecular syringes that inject bacterial virulence factors directly into host cells. These virulence factors manipulate host cell pathways to aid bacterial survival within the host. Four important enteric pathogens use TTSSs to colonize and persist within the intestinal environment. The following is a brief review of the way in which TTSSs and their effectors contribute to the pathogenic nature of the prototypic diarrheal pathogens Salmonella, Shigella, Yersinia and enteropathogenic Escherichia coli (EPEC).
Collapse
Affiliation(s)
- Michelle L Zaharik
- Biotechnology Laboratory, University of British Columbia, Vancouver, Canada
| | | | | | | |
Collapse
|
240
|
Knodler LA, Celli J, Hardt WD, Vallance BA, Yip C, Finlay BB. Salmonella effectors within a single pathogenicity island are differentially expressed and translocated by separate type III secretion systems. Mol Microbiol 2002; 43:1089-103. [PMID: 11918798 DOI: 10.1046/j.1365-2958.2002.02820.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Pathogenicity islands (PAIs) are large DNA segments in the genomes of bacterial pathogens that encode virulence factors. Five PAIs have been identified in the Gram-negative bacterium Salmonella enterica. Two of these PAIs, Salmonella pathogenicity island (SPI)-1 and SPI-2, encode type III secretion systems (TTSS), which are essential virulence determinants. These 'molecular syringes' inject effectors directly into the host cell, whereupon they manipulate host cell functions. These effectors are either encoded with their respective TTSS or scattered elsewhere on the Salmonella chromosome. Importantly, SPI-1 and SPI-2 are expressed under distinct environmental conditions: SPI-1 is induced upon initial contact with the host cell, whereas SPI-2 is induced intracellularly. Here, we demonstrate that a single PAI, in this case SPI-5, can encode effectors that are induced by distinct regulatory cues and targeted to different TTSS. SPI-5 encodes the SPI-1 TTSS translocated effector, SigD/SopB. In contrast, we report that the adjacently encoded effector PipB is part of the SPI-2 regulon. PipB is translocated by the SPI-2 TTSS to the Salmonella-containing vacuole and Salmonella-induced filaments. We also show that regions of SPI-5 are not conserved in all Salmonella spp. Although sigD/sopB is present in all Salmonella spp., pipB is not found in Salmonella bongori, which also lacks a functional SPI-2 TTSS. Thus, we demonstrate a functional and regulatory cross-talk between three chromosomal PAIs, SPI-1, SPI-2 and SPI-5, which has significant implications for the evolution and role of PAIs in bacterial pathogenesis.
Collapse
Affiliation(s)
- Leigh A Knodler
- Biotechnology Laboratory, Room 237, 6174 University Blvd, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | | | | | | | | | | |
Collapse
|
241
|
Ehrbar K, Mirold S, Friebel A, Stender S, Hardt WD. Characterization of effector proteins translocated via the SPI1 type III secretion system of Salmonella typhimurium. Int J Med Microbiol 2002; 291:479-85. [PMID: 11890547 DOI: 10.1078/1438-4221-00156] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Salmonella spp. employ a conserved type III secretion system encoded within the pathogenicity island 1 (SPI1; centisome 63) to translocate effector proteins into the host cytosol. The translocated effector proteins trigger diverse responses including bacterial internalization. In a mutation analysis we have defined the set of effector proteins mediating tissue culture cell invasion. This set includes sopE2 (centisome 40-42), sopB (SPI5, centisome 20) and in the case of S. typhimurium SL1344 also the phage-encoded effector sopE (SopEphi, centisome 59-60). A triple mutant SL1344 derivative deficient of SopE, SopE2 and SopB was more than 100-fold attenuated in tissue culture cell invasion. Phylogenetic analyses indicate that the last common ancestor of all contemporary Salmonella lineages already harbored all genes necessary for host cell invasion, namely the SPI1 type III secretion system, sopE2 and sopB. SopE, which is 70% identical to sopE2 is only present in some Salmonella strains and emerged later well after the divergence of the contemporary Salmonella lineages. Interestingly, S. typhimurium strains that harbor sopE are associated with epidemics, arguing that sopE is one of the factors determining the "fitness" of a strain. We found that SopE can specifically activate a different set of host cellular RhoGTPases than SopE2. This allows the bacteria to fine tune host cellular responses very precisely and may offer an explanation for the improved epidemic fitness of sopE-positive S. typhimurium strains.
Collapse
|
242
|
Abstract
Phagocytosis is an evolutionarily conserved process utilized by many cells to ingest microbial pathogens, and apoptotic and necrotic corpses. Recent investigation has revealed a fundamental requirement for two co-ordinated cellular processes--cytoskeletal alterations and membrane trafficking--in the phagocytic event. Some elements of this machinery are co-opted by certain pathogens to gain entry into host cells.
Collapse
Affiliation(s)
- Steven Greenberg
- Columbia University, Departments of Medicine and Pharmacology/BB914, 630 West 168th Street, New York, NY 10032, USA.
| | | |
Collapse
|
243
|
Lin M, Zhu MX, Rikihisa Y. Rapid activation of protein tyrosine kinase and phospholipase C-gamma2 and increase in cytosolic free calcium are required by Ehrlichia chaffeensis for internalization and growth in THP-1 cells. Infect Immun 2002; 70:889-98. [PMID: 11796624 PMCID: PMC127685 DOI: 10.1128/iai.70.2.889-898.2002] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Ehrlichia chaffeensis, a bacterium that cannot survive outside the eukaryotic cell, proliferates exclusively in human monocytes and macrophages. In this study, signaling events required for ehrlichial infection of human monocytic cell line THP-1 were characterized. Entry and proliferation of E. chaffeensis in THP-1 cells were significantly blocked by various inhibitors that can regulate calcium signaling, including 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate and 2-aminoethoxydiphenyl borate (intracellular calcium mobilization inhibitors), verapamil and 1-[beta-[3-(4-methoxyphenyl)propyl]-4-methoxyphenethyl]-1H-imidazole (SKF-96365) (calcium channel inhibitors), neomycin and 1-(6-[[17beta-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl)-1H-pyrrole-2,5-dione (U-73122) (phospholipase C [PLC] inhibitors), monodansylcadaverine (a transglutaminase [TGase] inhibitor), and genistein (a protein tyrosine kinase [PTK] inhibitor). Addition of E. chaffeensis resulted in rapid increases in the level of inositol 1,4,5-trisphosphate (IP(3)) and the level of cytosolic free calcium ([Ca(2+)](i)) in THP-1 cells, which were prevented by pretreatment of THP-1 cells with inhibitors of TGase, PTK, and PLC. E. chaffeensis induced rapid tyrosine phosphorylation of PLC-gamma2, and the presence of a PLC-gamma2 antisense oligonucleotide in THP-1 cells significantly blocked ehrlichial infection. Furthermore, tyrosine-phosphorylated proteins and PLC-gamma2 were colocalized with ehrlichial inclusions, as determined by double-immunofluorescence labeling. The heat-sensitive component of viable E. chaffeensis cells was essential for these signaling events. E. chaffeensis, therefore, can recruit interacting signal-transducing molecules and induce the following signaling events required for the establishment of infection in host cells: protein cross-linking by TGase, tyrosine phosphorylation, PLC-gamma2 activation, IP(3) production, and an increase in [Ca(2+)](i).
Collapse
Affiliation(s)
- Mingqun Lin
- Department of Veterinary Biosciences. Neurobiotechnology Center, The Ohio State University, Columbus, Ohio 43210, USA
| | | | | |
Collapse
|
244
|
Abstract
The bacterial pathogen Salmonella enterica has evolved a very sophisticated functional interface with its vertebrate hosts. At the center of this interface is a specialized organelle, the type III secretion system, that directs the translocation of bacterial proteins into the host cell. Salmonella spp. encode two such systems that deliver a remarkable array of bacterial proteins capable of modulating a variety of cellular functions, including actin cytoskeleton dynamics, nuclear responses, and endocytic trafficking. Many of these bacterial proteins operate by faithful mimicry of host proteins, in some cases representing the result of extensive molecular tinkering and convergent evolution. The coordinated action of these type III secreted proteins secures the replication and survival of the bacteria avoiding overt damage to the host. The study of this remarkable pathogen is not only illuminating general paradigms in microbial pathogenesis but is also providing valuable insight into host cell functions.
Collapse
Affiliation(s)
- J E Galán
- Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA.
| |
Collapse
|
245
|
Hayward RD, Koronakis V. Direct modulation of the host cell cytoskeleton by Salmonella actin-binding proteins. Trends Cell Biol 2002; 12:15-20. [PMID: 11854005 DOI: 10.1016/s0962-8924(01)02183-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Invasive Salmonella trigger their own uptake into non-phagocytic eukaryotic cells by delivering virulence proteins that stimulate signaling pathways and remodel the actin cytoskeleton. It has recently emerged that Salmonella encodes two actin-binding proteins, SipC and SipA, which together efficiently nucleate actin polymerization and stabilize the resulting supramolecular filament architecture. Therefore, Salmonella might directly initiate actin polymerization independently of the cellular Arp2/3 complex early in the cell entry process. This is an unprecedented example of a direct intervention strategy to facilitate entry of a pathogen into a target cell. Here, we discuss the Salmonella actin-binding proteins and how they might function in combination with entry effectors that stimulate Rho GTPases. We propose that membrane-targeted bacterial effector proteins might trigger actin polymerization through diverse mechanisms during cell entry by bacterial pathogens.
Collapse
Affiliation(s)
- Richard D Hayward
- University of Cambridge, Dept of Pathology, Tennis Court Road, CB2 1QP, Cambridge, UK.
| | | |
Collapse
|
246
|
Murli S, Watson RO, Galán JE. Role of tyrosine kinases and the tyrosine phosphatase SptP in the interaction of Salmonella with host cells. Cell Microbiol 2001; 3:795-810. [PMID: 11736992 DOI: 10.1046/j.1462-5822.2001.00158.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Salmonella has evolved an intimate functional interface with its host. Central to this interface is a battery of bacterial proteins delivered into host cells via a specialized organelle termed the type III secretion system. A subset of these bacterial proteins stimulates cellular responses by activating the Rho family GTPases Cdc42 and Rac. Stimulation of these responses leads to actin cytoskeleton reorganization and the activation of cellular transcription factors that result in bacterial uptake and proinflammatory cytokine production. Remarkably, the cellular responses stimulated by Salmonella are quickly reversed by another bacterial protein, SptP, which exerts its function as a GTPase-activating protein (GAP) for Cdc42 and Rac. In addition to its GAP activity located within its amino-terminus, the carboxy-terminal domain of SptP possesses potent tyrosine phosphatase activity. We show here that the tyrosine phosphatase activity of SptP is involved in reversing the MAP kinase activation that results from Salmonella infection. We also demonstrate an important role for tyrosine kinases, including ACK, in the cellular responses induced by Salmonella. We also found that a potential target for the tyrosine phosphatase activity of SptP is the intermediate filament protein vimentin, which is recruited to the membrane ruffles stimulated by Salmonella.
Collapse
Affiliation(s)
- S Murli
- Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale School of Medicine, New Haven, CT 06536, USA
| | | | | |
Collapse
|
247
|
Zhou D. Collective efforts to modulate the host actin cytoskeleton by Salmonella type III-secreted effector proteins. Trends Microbiol 2001; 9:567-9; discussion 569-70. [PMID: 11728859 DOI: 10.1016/s0966-842x(01)02227-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
248
|
Abstract
Phagocytosis of bacterial pathogens is at the heart of the pathogenesis of infections. Pathogens have evolved a large array of strategies to escape the deleterious effect of phagocytosis by professional phagocytes among which avoiding phagocytosis, killing the phagocytes or surviving inside them are the most 'popular' solutions. Bacterial pathogens are also using induction of phagocytic entry into non-professional phagocytic cells, such as epithelial cells, as a strategy of survival and multiplication. We have taken enteroinvasive micro-organisms such as Yersinia, Shigella and Salmonella as a paradigm of the significance of phagocytosis/antiphagocytosis in the development of an infection and on the elicitation of the host response.
Collapse
Affiliation(s)
- P Sansonetti
- Unité de Pathogénie Microbienne Moléculaire et Unité INSERM 389, Institut Pasteur, 28 Rue du Docteur Roux, 75724 Paris Cedex 15, France.
| |
Collapse
|
249
|
Collective efforts to modulate the host actin cytoskeleton by Salmonella type III-secreted effector proteins. Trends Microbiol 2001. [DOI: 10.1016/s0966-842x(01)02229-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
250
|
Zhou D, Galán J. Salmonella entry into host cells: the work in concert of type III secreted effector proteins. Microbes Infect 2001; 3:1293-8. [PMID: 11755417 DOI: 10.1016/s1286-4579(01)01489-7] [Citation(s) in RCA: 232] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Upon contact with intestinal epithelial cells, Salmonella enterica serovar spp. inject a set of bacterial proteins into host cells via the bacterial SPI-1 type III secretion system. SopE, SopE2 and SopB, activate CDC42 and Rac to initiate actin cytoskeleton rearrangements. SipA and SipC, two Salmonella actin-binding proteins, directly modulate host actin dynamics to facilitate bacterial uptake. SptP promotes the recovery of the actin cytoskeleton rearrangements by antagonizing CDC42 and Rac. Therefore, Salmonella-induced reversible actin cytoskeleton rearrangements are the result of two coordinated steps: (i) stimulation of host signal transduction to indirectly promote actin rearrangements and (ii) direct modulation of actin dynamics.
Collapse
Affiliation(s)
- D Zhou
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
| | | |
Collapse
|