1
|
Resnik N, Tratnjek L, Kreft ME, Kisovec M, Aden S, Bedina Zavec A, Anderluh G, Podobnik M, Veranič P. Cytotoxic Activity of LLO Y406A Is Targeted to the Plasma Membrane of Cancer Urothelial Cells. Int J Mol Sci 2021; 22:ijms22073305. [PMID: 33805017 PMCID: PMC8037347 DOI: 10.3390/ijms22073305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/19/2021] [Accepted: 03/21/2021] [Indexed: 01/01/2023] Open
Abstract
Identification of novel agents for bladder cancer treatment is highly desirable due to the high incidence of tumor recurrence and the risk of progression to muscle-invasive disease. The key feature of the cholesterol-dependent toxin listeriolysin O mutant (LLO Y406A) is its preferential activity at pH 5.7, which could be exploited either directly for selective targeting of cancer cells or the release of accumulated therapeutics from acidic endosomes. Therefore, our goal was to compare the cytotoxic effect of LLO Y406A on cancer cells (RT4) and normal urothelial cells (NPU), and to identify which cell membranes are the primary target of LLO Y406A by viability assays, life-cell imaging, fluorescence, and electron microscopy. LLO Y406A decreased viability, altered cell morphology, provoked membrane blebbing, and induced apoptosis in RT4 cells, while it did not affect NPU cells. LLO Y406A did not cause endosomal escape in RT4 cells, while the plasma membrane of RT4 cells was revealed as the primary target of LLO Y406A. It has been concluded that LLO Y406A has the ability to selectively eliminate cancer urothelial cells through pore-forming activity at the plasma membrane, without cytotoxic effects on normal urothelial cells. This promising selective activity merits further testing as an anti-cancer agent.
Collapse
Affiliation(s)
- Nataša Resnik
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.R.); (L.T.); (M.E.K.)
| | - Larisa Tratnjek
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.R.); (L.T.); (M.E.K.)
| | - Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.R.); (L.T.); (M.E.K.)
| | - Matic Kisovec
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (S.A.); (A.B.Z.); (G.A.); (M.P.)
| | - Saša Aden
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (S.A.); (A.B.Z.); (G.A.); (M.P.)
| | - Apolonija Bedina Zavec
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (S.A.); (A.B.Z.); (G.A.); (M.P.)
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (S.A.); (A.B.Z.); (G.A.); (M.P.)
| | - Marjetka Podobnik
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; (M.K.); (S.A.); (A.B.Z.); (G.A.); (M.P.)
| | - Peter Veranič
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (N.R.); (L.T.); (M.E.K.)
- Correspondence: ; Tel.: +386-1-543-7682
| |
Collapse
|
2
|
Maurer J, Hupp S, Pillich H, Mitchell TJ, Chakraborty T, Iliev AI. Missing elimination via membrane vesicle shedding contributes to the diminished calcium sensitivity of listeriolysin O. Sci Rep 2018; 8:15846. [PMID: 30367146 PMCID: PMC6203718 DOI: 10.1038/s41598-018-34031-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 10/10/2018] [Indexed: 01/08/2023] Open
Abstract
The lytic capacity of cholesterol-dependent cytolysins is enhanced in the extracellular calcium-free environment through a combination of limited membrane repair and diminished membrane toxin removal. For a typical neurotoxin of the group, pneumolysin, this effect has already been observed at reduced (1 mM) calcium conditions, which are pathophysiologically relevant. Here, we tested another neurotoxin of the group, listeriolysin O from L. monocytogenes, active in the primary vacuole after bacterium phagocytosis in host cells. Reduced calcium did not increase the lytic capacity of listeriolysin (in contrast to pneumolysin), while calcium-free conditions elevated it 2.5 times compared to 10 times for pneumolysin (at equivalent hemolytic capacities). To clarify these differences, we analyzed membrane vesicle shedding, known to be a calcium-dependent process for toxin removal from eukaryotic cell membranes. Both pneumolysin and listeriolysin initiated vesicle shedding, which was completely blocked by the lack of extracellular calcium. Lack of calcium, however, elevated the toxin load per a cell only for pneumolysin and not for listeriolysin. This result indicates that vesicle shedding does not play a role in the membrane removal of listeriolysin and outlines a major difference between it and other members of the CDC group. Furthermore, it provides new tools for studying membrane vesicle shedding.
Collapse
Affiliation(s)
- Jana Maurer
- Institute of Physiology and Pathophysiology, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany.,DFG Membrane/Cytoskeleton Interaction Group, Institute of Pharmacology and Toxicology and Rudolf Virchow Center for Experimental Biomedical Science, University of Würzburg, Versbacherstr. 9, 97078, Würzburg, Germany
| | - Sabrina Hupp
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012, Bern, Switzerland.,DFG Membrane/Cytoskeleton Interaction Group, Institute of Pharmacology and Toxicology and Rudolf Virchow Center for Experimental Biomedical Science, University of Würzburg, Versbacherstr. 9, 97078, Würzburg, Germany
| | - Helena Pillich
- Institute of Medical Microbiology, Justus Liebig University Giessen, Schubertstr. 81, 35392, Giessen, Germany.,German Centre for Infection research (DZIF), Partner site Giessen-Marburg-Langen, Campus Giessen, Giessen, Germany
| | - Timothy J Mitchell
- Chair of Microbial Infection and Immunity, School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Trinad Chakraborty
- Institute of Medical Microbiology, Justus Liebig University Giessen, Schubertstr. 81, 35392, Giessen, Germany.,German Centre for Infection research (DZIF), Partner site Giessen-Marburg-Langen, Campus Giessen, Giessen, Germany
| | - Asparouh I Iliev
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, 3012, Bern, Switzerland. .,DFG Membrane/Cytoskeleton Interaction Group, Institute of Pharmacology and Toxicology and Rudolf Virchow Center for Experimental Biomedical Science, University of Würzburg, Versbacherstr. 9, 97078, Würzburg, Germany.
| |
Collapse
|
3
|
Osborne SE, Brumell JH. Listeriolysin O: from bazooka to Swiss army knife. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630160 DOI: 10.1098/rstb.2016.0222] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Listeria monocytogenes (Lm) is a Gram-positive facultative intracellular pathogen. Infections in humans can lead to listeriosis, a systemic disease with a high mortality rate. One important mechanism of Lm dissemination involves cell-to-cell spread after bacteria have entered the cytosol of host cells. Listeriolysin O (LLO; encoded by the hly gene) is a virulence factor present in Lm that plays a central role in the cell-to-cell spread process. LLO is a member of the cholesterol-dependent cytolysin (CDC) family of toxins that were initially thought to promote disease largely by inducing cell death and tissue destruction-essentially acting like a 'bazooka'. This view was supported by structural studies showing CDCs can form large pores in membranes. However, it is now appreciated that LLO has many subtle activities during Lm infection of host cells, and many of these likely do not involve large pores, but rather small membrane perforations. It is also appreciated that membrane repair pathways of host cells play a major role in limiting membrane damage by LLO and other toxins. LLO is now thought to represent a 'Swiss army knife', a versatile tool that allows Lm to induce many membrane alterations and cellular responses that promote bacterial dissemination during infection.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
Collapse
Affiliation(s)
- Suzanne E Osborne
- Cell Biology Program, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8
| | - John H Brumell
- Cell Biology Program, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8 .,Sickkids IBD Centre, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada M5S 1A8.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8
| |
Collapse
|
4
|
Rezelj S, Kozorog M, Švigelj T, Ulrih NP, Žnidaršič N, Podobnik M, Anderluh G. Cholesterol Enriched Archaeosomes as a Molecular System for Studying Interactions of Cholesterol-Dependent Cytolysins with Membranes. J Membr Biol 2018; 251:491-505. [DOI: 10.1007/s00232-018-0018-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 02/05/2018] [Indexed: 12/31/2022]
|
5
|
Rampersaud R, Lewis EL, LaRocca TJ, Ratner AJ. Environmental pH modulates inerolysin activity via post-binding blockade. Sci Rep 2018; 8:1542. [PMID: 29367601 PMCID: PMC5784117 DOI: 10.1038/s41598-018-19994-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 01/11/2018] [Indexed: 11/29/2022] Open
Abstract
The cholesterol dependent cytolysins (CDCs) are a family of pore-forming toxins produced by a wide range of bacteria. Some CDCs are important virulence factors for their cognate organisms, but their activity must be tightly regulated to ensure they operate at appropriate times and within the appropriate subcellular compartments. pH-dependent activity has been described for several CDCs, but the mechanism of such regulation has been studied in depth only for listeriolysin O (LLO), which senses environmental pH through a triad of acidic residues that mediate protein unfolding. Here we present data supporting a distinct mechanism for pH-dependence for inerolysin (INY), the CDC produced by Lactobacillus iners. Inerolysin (INY) has an acidic pH optimum with loss of activity at neutral pH. INY pH-dependence is characterized by reversible loss of pore formation with preservation of membrane binding. Fluorescent membrane probe assays indicated that INY insertion into host cell membranes, but not oligomerization, was defective at neutral pH. These data support the existence of a newly appreciated form of CDC pH-dependence functioning at a late stage of pore formation.
Collapse
Affiliation(s)
- Ryan Rampersaud
- College of Physicians & Surgeons, Columbia University, New York, NY, USA.,Department of Psychiatry, University of California, San Francisco, CA, USA
| | - Emma L Lewis
- College of Physicians & Surgeons, Columbia University, New York, NY, USA.,Perelman School of Medicine, University of Pennsylvania, Pennsylvania, PA, USA
| | - Timothy J LaRocca
- College of Physicians & Surgeons, Columbia University, New York, NY, USA.,Department of Basic & Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY, USA
| | - Adam J Ratner
- College of Physicians & Surgeons, Columbia University, New York, NY, USA. .,Department of Pediatrics, New York University School of Medicine, New York, NY, USA. .,Department of Microbiology, New York University School of Medicine, New York, NY, USA.
| |
Collapse
|
6
|
Abstract
Listeriolysin O (LLO) is a cytolysin capable of forming pores in cholesterol-rich lipid membranes of host cells. It is conveniently suited for engineering a pH-governed responsiveness, due to a pH sensor identified in its structure that was shown before to affect its stability. Here we introduced a new level of control of its hemolytic activity by making a variant with hemolytic activity that was pH-dependent. Based on detailed structural analysis coupled with molecular dynamics and mutational analysis, we found that the bulky side chain of Tyr406 allosterically affects the pH sensor. Molecular dynamics simulation further suggested which other amino acid residues may also allosterically influence the pH-sensor. LLO was engineered to the point where it can, in a pH-regulated manner, perforate artificial and cellular membranes. The single mutant Tyr406Ala bound to membranes and oligomerized similarly to the wild-type LLO, however, the final membrane insertion step was pH-affected by the introduced mutation. We show that the mutant toxin can be activated at the surface of artificial membranes or living cells by a single wash with slightly acidic pH buffer. Y406A mutant has a high potential in development of novel nanobiotechnological applications such as controlled release of substances or as a sensor of environmental pH.
Collapse
|
7
|
Ruan Y, Rezelj S, Bedina Zavec A, Anderluh G, Scheuring S. Listeriolysin O Membrane Damaging Activity Involves Arc Formation and Lineaction -- Implication for Listeria monocytogenes Escape from Phagocytic Vacuole. PLoS Pathog 2016; 12:e1005597. [PMID: 27104344 PMCID: PMC4841516 DOI: 10.1371/journal.ppat.1005597] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/04/2016] [Indexed: 12/15/2022] Open
Abstract
Listeriolysin-O (LLO) plays a crucial role during infection by Listeria monocytogenes. It enables escape of bacteria from phagocytic vacuole, which is the basis for its spread to other cells and tissues. It is not clear how LLO acts at phagosomal membranes to allow bacterial escape. The mechanism of action of LLO remains poorly understood, probably due to unavailability of suitable experimental tools that could monitor LLO membrane disruptive activity in real time. Here, we used high-speed atomic force microscopy (HS-AFM) featuring high spatio-temporal resolution on model membranes and optical microscopy on giant unilamellar vesicles (GUVs) to investigate LLO activity. We analyze the assembly kinetics of toxin oligomers, the prepore-to-pore transition dynamics and the membrane disruption in real time. We reveal that LLO toxin efficiency and mode of action as a membrane-disrupting agent varies strongly depending on the membrane cholesterol concentration and the environmental pH. We discovered that LLO is able to form arc pores as well as damage lipid membranes as a lineactant, and this leads to large-scale membrane defects. These results altogether provide a mechanistic basis of how large-scale membrane disruption leads to release of Listeria from the phagocytic vacuole in the cellular context.
Collapse
Affiliation(s)
- Yi Ruan
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - Saša Rezelj
- Department for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Apolonija Bedina Zavec
- Department for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Gregor Anderluh
- Department for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
- * E-mail: (SS); (GA)
| | - Simon Scheuring
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, Marseille, France
- * E-mail: (SS); (GA)
| |
Collapse
|
8
|
Perforin-2 Protects Host Cells and Mice by Restricting the Vacuole to Cytosol Transitioning of a Bacterial Pathogen. Infect Immun 2016; 84:1083-1091. [PMID: 26831467 DOI: 10.1128/iai.01434-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Accepted: 01/23/2016] [Indexed: 12/20/2022] Open
Abstract
The host-encoded Perforin-2 (encoded by the macrophage-expressed gene 1, Mpeg1), which possesses a pore-forming MACPF domain, reduces the viability of bacterial pathogens that reside within membrane-bound compartments. Here, it is shown that Perforin-2 also restricts the proliferation of the intracytosolic pathogen Listeria monocytogenes Within a few hours of systemic infection, the massive proliferation of L. monocytogenes in Perforin-2(-/-)mice leads to a rapid appearance of acute disease symptoms. We go on to show in cultured Perforin-2(-/-)cells that the vacuole-to-cytosol transitioning of L. monocytogenesis greatly accelerated. Unexpectedly, we found that in Perforin-2(-/-)macrophages,Listeria-containing vacuoles quickly (≤ 15 min) acidify, and that this was coincident with greater virulence gene expression, likely accounting for the more rapid translocation of L. monocytogenes to its replicative niche in the cytosol. This hypothesis was supported by our finding that aL. monocytogenes strain expressing virulence factors at a constitutively high level replicated equally well in Perforin-2(+/+)and Perforin-2(-/-)macrophages. Our findings suggest that the protective role of Perforin-2 against listeriosis is based on it limiting the intracellular replication of the pathogen. This cellular activity of Perforin-2 may derive from it regulating the acidification of Listeria-containing vacuoles, thereby depriving the pathogen of favorable intracellular conditions that promote its virulence gene activity.
Collapse
|
9
|
Podobnik M, Marchioretto M, Zanetti M, Bavdek A, Kisovec M, Cajnko MM, Lunelli L, Dalla Serra M, Anderluh G. Plasticity of listeriolysin O pores and its regulation by pH and unique histidine [corrected]. Sci Rep 2015; 5:9623. [PMID: 25854672 PMCID: PMC5381700 DOI: 10.1038/srep09623] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/12/2015] [Indexed: 12/12/2022] Open
Abstract
Pore formation of cellular membranes is an ancient mechanism of bacterial pathogenesis that allows efficient damaging of target cells. Several mechanisms have been described, however, relatively little is known about the assembly and properties of pores. Listeriolysin O (LLO) is a pH-regulated cholesterol-dependent cytolysin from the intracellular pathogen Listeria monocytogenes, which forms transmembrane β-barrel pores. Here we report that the assembly of LLO pores is rapid and efficient irrespective of pH. While pore diameters at the membrane surface are comparable at either pH 5.5 or 7.4, the distribution of pore conductances is significantly pH-dependent. This is directed by the unique residue H311, which is also important for the conformational stability of the LLO monomer and the rate of pore formation. The functional pores exhibit variations in height profiles and can reconfigure significantly by merging to other full pores or arcs. Our results indicate significant plasticity of large β-barrel pores, controlled by environmental cues like pH.
Collapse
Affiliation(s)
- Marjetka Podobnik
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Marta Marchioretto
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche &Fondazione Bruno Kessler, via alla Cascata 56/C, 38123 Trento, Italy
| | - Manuela Zanetti
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche &Fondazione Bruno Kessler, via alla Cascata 56/C, 38123 Trento, Italy
| | - Andrej Bavdek
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Matic Kisovec
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Miša Mojca Cajnko
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Lorenzo Lunelli
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche &Fondazione Bruno Kessler, via alla Cascata 56/C, 38123 Trento, Italy
| | - Mauro Dalla Serra
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche &Fondazione Bruno Kessler, via alla Cascata 56/C, 38123 Trento, Italy
| | - Gregor Anderluh
- 1] Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia [2] Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| |
Collapse
|
10
|
Listeria monocytogenes exploits efferocytosis to promote cell-to-cell spread. Nature 2014; 509:230-4. [PMID: 24739967 PMCID: PMC4151619 DOI: 10.1038/nature13168] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 02/21/2014] [Indexed: 11/08/2022]
Abstract
Efferocytosis, the process by which dying or dead cells are removed by phagocytosis, has an important role in development, tissue homeostasis and innate immunity. Efferocytosis is mediated, in part, by receptors that bind to exofacial phosphatidylserine (PS) on cells or cellular debris after loss of plasma membrane asymmetry. Here we show that a bacterial pathogen, Listeria monocytogenes, can exploit efferocytosis to promote cell-to-cell spread during infection. These bacteria can escape the phagosome in host cells by using the pore-forming toxin listeriolysin O (LLO) and two phospholipase C enzymes. Expression of the cell surface protein ActA allows L. monocytogenes to activate host actin regulatory factors and undergo actin-based motility in the cytosol, eventually leading to formation of actin-rich protrusions at the cell surface. Here we show that protrusion formation is associated with plasma membrane damage due to LLO's pore-forming activity. LLO also promotes the release of bacteria-containing protrusions from the host cell, generating membrane-derived vesicles with exofacial PS. The PS-binding receptor TIM-4 (encoded by the Timd4 gene) contributes to efficient cell-to-cell spread by L. monocytogenes in macrophages in vitro and growth of these bacteria is impaired in Timd4(-/-) mice. Thus, L. monocytogenes promotes its dissemination in a host by exploiting efferocytosis. Our results indicate that PS-targeted therapeutics may be useful in the fight against infections by L. monocytogenes and other bacteria that use similar strategies of cell-to-cell spread during infection.
Collapse
|
11
|
Bavdek A, Kostanjšek R, Antonini V, Lakey JH, Dalla Serra M, Gilbert RJC, Anderluh G. pH dependence of listeriolysin O aggregation and pore-forming ability. FEBS J 2011; 279:126-41. [PMID: 22023160 DOI: 10.1111/j.1742-4658.2011.08405.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Listeriolysin O (LLO) is the major factor implicated in the escape of Listeria monocytogenes from the phagolysosome. It is the only representative of cholesterol-dependent cytolysins that exhibits pH-dependent activity. Despite intense studies of LLO pH-dependence, this feature of the toxin still remains incompletely explained. Here we used fluorescence and CD spectroscopy to show that the structure of LLO is not detectably affected by pH at room temperature. We observed slightly altered haemolytic and permeabilizing activities at different pH values, which we relate to reduced binding of LLO to the lipid membranes. However, alkaline pH and elevated temperatures caused rapid denaturation of LLO. Aggregates of the toxin were able to bind Congo red and Thioflavin T dyes and were visible under transmission electron microscopy as large, amorphous, micrometer-sized assemblies. The aggregates had the biophysical properties of amyloid. Analytical ultracentrifugation indicated dimerization of the protein in acidic conditions, which protects the protein against premature denaturation in the phagolysosome, where toxin activity takes place. We therefore suggest that LLO spontaneously aggregates at the neutral pH found in the host cell cytosol and that this is a major mechanism of LLO inactivation.
Collapse
Affiliation(s)
- Andrej Bavdek
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | | | | | | | | | | | | |
Collapse
|
12
|
Stachowiak R, Wiśniewski J, Osińska O, Bielecki J. Contribution of cysteine residue to the properties of Listeria monocytogenes listeriolysin O. Can J Microbiol 2010; 55:1153-9. [PMID: 19935887 DOI: 10.1139/w09-070] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Listeriolysin (LLO) is the key virulence factor critical for Listeria monocytogenes pathogenesis. Listerial cytolysin belongs to the family of cholesterol-dependent cytolysins (CDCs), a group of pore-forming toxins produced by related gram-positive bacteria. Most CDCs contain a cysteine residue in the conserved undecapeptide - a sequence that is highly preserved among this group of proteins. Substitutions of cysteine do not always lead to loss of hemolytic activity, questioning the purpose of such strong conservation of this amino acid in the sequence of CDC. The properties of 3 L. monocytogenes strains, a wild type and 2 mutants expressing modified LLO within the cysteine residue, were analyzed in this work. The first of these mutants producing a toxin with cysteine to alanine substitution showed similar features to the wild type except that a thiol-reducing agent was not necessary for hemolytic activity. Another strain secreting LLO containing serine instead of cysteine exhibited strikingly different properties than the wild type. Modified toxin is independent of the reducing reagents, less stable, and shows accelerated kinetics of cytolysis in comparison with the unchanged protein. However, both mutant strains are less invasive in the cell culture model showing the important role of cysteine in L. monocytogenes virulence.
Collapse
Affiliation(s)
- Radosław Stachowiak
- Department of Applied Microbiology, Institute of Microbiology, University of Warsaw, Miecznikowa 1, Warsaw 02-096, Poland.
| | | | | | | |
Collapse
|
13
|
Listeriolysin O-dependent bacterial entry into the cytoplasm is required for calpain activation and interleukin-1 alpha secretion in macrophages infected with Listeria monocytogenes. Infect Immun 2010; 78:1884-94. [PMID: 20194588 DOI: 10.1128/iai.01143-09] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Listeriolysin O (LLO), an hly-encoded cytolysin of Listeria monocytogenes, plays an essential role in the entry of L. monocytogenes into the host cell cytoplasm. L. monocytogenes-infected macrophages produce various proinflammatory cytokines, including interleukin-1 alpha (IL-1 alpha), that contribute to the host immune response. In this study, we have examined IL-1 alpha production in macrophages infected with wild-type L. monocytogenes or a nonescaping mutant strain deficient for LLO (Delta hly). Expression of IL-1 alpha mRNA and accumulation of pro-IL-1 alpha in the cytoplasm were induced by both strains. In contrast, the secretion of the mature form of IL-1 alpha from infected macrophages was observed in infection with wild-type L. monocytogenes but not with the Delta hly mutant. A recovery of the ability to induce IL-1 alpha secretion was shown in a mutant strain complemented with the hly gene. The Toll-like receptor (TLR)/MyD88 signaling pathway was exclusively required for the expression of pro-IL-1 alpha, independently of LLO-mediated cytoplasmic entry of L. monocytogenes. The LLO-dependent secretion of mature IL-1 alpha was abolished by addition of calcium chelators, and only LLO-producing L. monocytogenes strains were able to induce elevation of the intracellular calcium level in infected macrophages. A calcium-dependent protease, calpain, was implicated in the maturation and secretion of IL-1 alpha induced by LLO-producing L. monocytogenes strains based on the effect of calpain inhibitor. Functional activation of calpain was detected in macrophages infected with LLO-producing L. monocytogenes strains but not with a mutant strain lacking LLO. These results clearly indicated that LLO-mediated cytoplasmic entry of bacteria could induce the activation of intracellular calcium signaling, which is essential for maturation and secretion of IL-1 alpha in macrophages during L. monocytogenes infection through activation of a calcium-dependent calpain protease. In addition, recombinant LLO, when added to macrophages infected with the Delta hly strain, could induce calcium influx and IL-1 alpha secretion at doses exhibiting cytolytic activity, suggesting that LLO produced by intracellular L. monocytogenes may be implicated in induction of calcium influx through pore formation.
Collapse
|
14
|
Mitsuyama M. [Mechanism for the induction of host immune response by virulence factors of Listeria monocytogenes]. Nihon Saikingaku Zasshi 2009; 64:365-76. [PMID: 20023369 DOI: 10.3412/jsb.64.365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Masao Mitsuyama
- Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| |
Collapse
|
15
|
Francisella tularensis phagosomal escape does not require acidification of the phagosome. Infect Immun 2009; 77:1757-73. [PMID: 19237528 DOI: 10.1128/iai.01485-08] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Following uptake, Francisella tularensis enters a phagosome that acquires limited amounts of lysosome-associated membrane glycoproteins and does not acquire cathepsin D or markers of secondary lysosomes. With additional time after uptake, F. tularensis disrupts its phagosomal membrane and escapes into the cytoplasm. To assess the role of phagosome acidification in phagosome escape, we followed acidification using the vital stain LysoTracker red and acquisition of the proton vacuolar ATPase (vATPase) using immunofluorescence within the first 3 h after uptake of live or killed F. tularensis subsp. holarctica live vaccine strain (LVS) by human macrophages. Whereas 90% of the phagosomes containing killed LVS stained intensely for the vATPase and were acidified, only 20 to 30% of phagosomes containing live LVS stained intensely for the vATPase and were acidified. To determine whether transient acidification might be required for phagosome escape, we assessed the impact on phagosome permeabilization of the proton pump inhibitor bafilomycin A. Using electron microscopy and an adenylate cyclase reporter system, we found that bafilomycin A did not prevent phagosomal permeabilization by F. tularensis LVS or virulent type A strains (F. tularensis subsp. tularensis strain Schu S4 and a recent clinical isolate) or by "F. tularensis subsp. novicida," indicating that F. tularensis disrupts its phagosomal membrane by a mechanism that does not require acidification.
Collapse
|
16
|
Hara H, Tsuchiya K, Nomura T, Kawamura I, Shoma S, Mitsuyama M. Dependency of caspase-1 activation induced in macrophages by Listeria monocytogenes on cytolysin, listeriolysin O, after evasion from phagosome into the cytoplasm. THE JOURNAL OF IMMUNOLOGY 2008; 180:7859-68. [PMID: 18523249 DOI: 10.4049/jimmunol.180.12.7859] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Listeriolysin O (LLO), an hly-encoded cytolysin from Listeria monocytogenes, plays an essential role in the entry of this pathogen into the macrophage cytoplasm and is also a key factor in inducing the production of IFN-gamma during the innate immune stage of infection. In this study, we examined the involvement of LLO in macrophage production of the IFN-gamma-inducing cytokines IL-12 and IL-18. Significant levels of IL-12 and IL-18 were produced by macrophages upon infection with wild-type L. monocytogenes, whereas an LLO-deficient mutant (the L. monocytogenes Deltahly) lacked the ability to induce IL-18 production. Complementation of Deltahly with hly completely restored the ability. However, when Deltahly was complemented with ilo encoding ivanolysin O (ILO), a cytolysin highly homologous with LLO, such a restoration was not observed, although ILO-expressing L. monocytogenes invaded and multiplied in the macrophage cytoplasm similarly as LLO-expressing L. monocytogenes. Induction of IL-18 was diminished when pretreated with a caspase-1 inhibitor or in macrophages from caspase-1-deficient mice, suggesting the activation of caspase-1 as a key event resulting in IL-18 production. Activation of caspase-1 was induced in macrophages infected with LLO-expressing L. monocytogenes but not in those with Deltahly. A complete restoration of such an activity could not be observed even after complementation with the ILO gene. These results show that the LLO molecule is involved in the activation of caspase-1, which is essential for IL-18 production in infected macrophages, and suggest that some sequence unique to LLO is indispensable for some signaling event resulting in the caspase-1 activation induced by L. monocytogenes.
Collapse
Affiliation(s)
- Hideki Hara
- Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | | | | | | | | | | |
Collapse
|