1
|
Guk K, Yi S, Kim H, Kim S, Lim EK, Kang T, Jung J. PoreGlow: A split green fluorescent protein-based system for rapid detection of Listeria monocytogenes. Food Chem 2024; 438:138043. [PMID: 37992606 DOI: 10.1016/j.foodchem.2023.138043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 11/06/2023] [Accepted: 11/17/2023] [Indexed: 11/24/2023]
Abstract
Listeria monocytogenes, a severe foodborne pathogen causing severe diseases underscores the necessity for the development of a detection system with high specificity, sensitivity and utility. Herein, the PoreGlow system, based on split green fluorescent protein (GFP), was developed and assessed for the fast and accurate detection of L. monocytogenes. Split GFP-encapsulated liposomes were optimized for targeted analysis. The system utilizes listeriolysin O (LLO), a toxin produced by L. monocytogenes that enlarges the pores split GFP-encapsulated liposomes, to detect L. monocytogenes by measuring the fluorescent signal generated when the encapsulated GFP is released and reacted with the externally added fragment of the split GFP. The system exhibited a limit of detection of 0.17 μg/ml for LLO toxin and 10 CFU/mL for L. monocytogenes with high sensitivity and specificity and no cross-reactivity with other bacteria. The PoreGlow system is practical, rapid, and does not require sample pre-treatment, making it a promising tool for the early detection of L. monocytogenes in food products, which is crucial for preventing outbreaks and protecting public health.
Collapse
Affiliation(s)
- Kyeonghye Guk
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Soyeon Yi
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Hyeran Kim
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Suhyeon Kim
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Eun-Kyung Lim
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Nanobiotechnology, KRIBB School of Biotechnology, UST, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea; School of Pharmacy, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Republic of Korea
| | - Taejoon Kang
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; School of Pharmacy, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Republic of Korea
| | - Juyeon Jung
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Nanobiotechnology, KRIBB School of Biotechnology, UST, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea; School of Pharmacy, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Republic of Korea.
| |
Collapse
|
2
|
Shahi I, Dongas SA, Ilmain JK, Torres VJ, Ratner AJ. Characterization of tigurilysin, a novel human CD59-specific cholesterol-dependent cytolysin, reveals a role for host specificity in augmenting toxin activity. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001393. [PMID: 37702594 PMCID: PMC10569062 DOI: 10.1099/mic.0.001393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/05/2023] [Indexed: 09/14/2023]
Abstract
Cholesterol-dependent cytolysins (CDCs) are a large family of pore-forming toxins, produced by numerous Gram-positive pathogens. CDCs depend on host membrane cholesterol for pore formation; some CDCs also require surface-associated human CD59 (hCD59) for binding, conferring specificity for human cells. We purified a recombinant version of a putative CDC encoded in the genome of Streptococcus oralis subsp. tigurinus, tigurilysin (TGY), and used CRISPR/Cas9 to construct hCD59 knockout (KO) HeLa and JEG-3 cell lines. Cell viability assays with TGY on wild-type and hCD59 KO cells showed that TGY is a hCD59-dependent CDC. Two variants of TGY exist among S. oralis subsp. tigurinus genomes, only one of which is functional. We discovered that a single amino acid change between these two TGY variants determines its activity. Flow cytometry and oligomerization Western blots revealed that the single amino acid difference between the two TGY isoforms disrupts host cell binding and oligomerization. Furthermore, experiments with hCD59 KO cells and cholesterol-depleted cells demonstrated that TGY is fully dependent on both hCD59 and cholesterol for activity, unlike other known hCD59-dependent CDCs. Using full-length CDCs and toxin constructs differing only in the binding domain, we determined that having hCD59 dependence leads to increased lysis efficiency, conferring a potential advantage to organisms producing hCD59-dependent CDCs.
Collapse
Affiliation(s)
- Ifrah Shahi
- Department of Pediatrics, New York University Grossman School of Medicine, New York, NY, USA
| | - Sophia A. Dongas
- Department of Pediatrics, New York University Grossman School of Medicine, New York, NY, USA
| | - Juliana K. Ilmain
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Victor J. Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Adam J. Ratner
- Department of Pediatrics, New York University Grossman School of Medicine, New York, NY, USA
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| |
Collapse
|
3
|
Shahi I, Dongas SA, Ilmain JK, Torres VJ, Ratner AJ. Characterization of Tigurilysin, a Novel Human CD59-Specific Cholesterol-Dependent Cytolysin, Reveals a Role for Host Specificity in Augmenting Toxin Activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.21.545930. [PMID: 37546867 PMCID: PMC10401958 DOI: 10.1101/2023.06.21.545930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Cholesterol dependent cytolysins (CDCs) are a large family of pore forming toxins, produced by numerous gram-positive pathogens. CDCs depend on host membrane cholesterol for pore formation; some CDCs also require surface associated human CD59 (hCD59) for binding, conferring specificity for human cells. We purified a recombinant version of a putative CDC encoded in the genome of Streptococcus oralis subsp. tigurinus , tigurilysin (TGY), and used CRISPR/Cas9 to construct hCD59 knockout (KO) HeLa and JEG-3 cell lines. Cell viability assays with TGY on WT and hCD59 KO cells showed that TGY is a hCD59-dependent CDC. Two variants of TGY exist among S. oralis subsp. tigurinus genomes, only one of which is functional. We discovered that a single amino acid change between these two TGY variants determines its activity. Flow cytometry and oligomerization western blots revealed that the single amino acid difference between the two TGY isoforms disrupts host cell binding and oligomerization. Furthermore, experiments with hCD59 KO cells and cholesterol depleted cells demonstrated that TGY is fully dependent on both hCD59 and cholesterol for activity, unlike other known hCD59-dependent CDCs. Using full-length CDCs and toxin constructs differing only in the binding domain, we determined that having hCD59-dependence leads to increased lysis efficiency, conferring a potential advantage to organisms producing hCD59-dependent CDCs. IMPORTANCE Cholesterol dependent cytolysins (CDCs) are produced by a variety of disease-causing bacteria, and may play a significant role in pathogenesis. Understanding CDC mechanisms of action provides useful information for developing anti-virulence strategies against bacteria that utilize CDCs and other pore-forming toxins in pathogenesis. This study describes for the first time a novel human-specific CDC with an atypical pore forming mechanism compared to known CDCs. In addition, this study demonstrates that human-specificity potentially confers increased lytic efficiency to CDCs. These data provide a possible explanation for the selective advantage of developing hCD59-dependency in CDCs and the consequent host restriction.
Collapse
Affiliation(s)
- Ifrah Shahi
- New York University Grossman School of Medicine, Department of Pediatrics, New York, NY
| | - Sophia A. Dongas
- New York University Grossman School of Medicine, Department of Pediatrics, New York, NY
| | - Juliana K. Ilmain
- New York University Grossman School of Medicine, Department of Microbiology, New York, NY
| | - Victor J. Torres
- New York University Grossman School of Medicine, Department of Microbiology, New York, NY
| | - Adam J. Ratner
- New York University Grossman School of Medicine, Department of Pediatrics, New York, NY
- New York University Grossman School of Medicine, Department of Microbiology, New York, NY
| |
Collapse
|
4
|
Whiting R, Stanton S, Kucheriava M, Smith AR, Pitts M, Robertson D, Kammer J, Li Z, Fologea D. Hypo-Osmotic Stress and Pore-Forming Toxins Adjust the Lipid Order in Sheep Red Blood Cell Membranes. MEMBRANES 2023; 13:620. [PMID: 37504986 PMCID: PMC10385129 DOI: 10.3390/membranes13070620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/07/2023] [Accepted: 06/22/2023] [Indexed: 07/29/2023]
Abstract
Lipid ordering in cell membranes has been increasingly recognized as an important factor in establishing and regulating a large variety of biological functions. Multiple investigations into lipid organization focused on assessing ordering from temperature-induced phase transitions, which are often well outside the physiological range. However, particular stresses elicited by environmental factors, such as hypo-osmotic stress or protein insertion into membranes, with respect to changes in lipid status and ordering at constant temperature are insufficiently described. To fill these gaps in our knowledge, we exploited the well-established ability of environmentally sensitive membrane probes to detect intramembrane changes at the molecular level. Our steady state fluorescence spectroscopy experiments focused on assessing changes in optical responses of Laurdan and diphenylhexatriene upon exposure of red blood cells to hypo-osmotic stress and pore-forming toxins at room temperature. We verified our utilized experimental systems by a direct comparison of the results with prior reports on artificial membranes and cholesterol-depleted membranes undergoing temperature changes. The significant changes observed in the lipid order after exposure to hypo-osmotic stress or pore-forming toxins resembled phase transitions of lipids in membranes, which we explained by considering the short-range interactions between membrane components and the hydrophobic mismatch between membrane thickness and inserted proteins. Our results suggest that measurements of optical responses from the membrane probes constitute an appropriate method for assessing the status of lipids and phase transitions in target membranes exposed to mechanical stresses or upon the insertion of transmembrane proteins.
Collapse
Affiliation(s)
- Rose Whiting
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Sevio Stanton
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | | | - Aviana R Smith
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Matt Pitts
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Daniel Robertson
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Jacob Kammer
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Department of Family Medicine, Idaho College of Osteopathic Medicine, Meridian, ID 83642, USA
| | - Zhiyu Li
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Daniel Fologea
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| |
Collapse
|
5
|
Haram CS, Moitra S, Keane R, Kuhlmann FM, Frankfater C, Hsu FF, Beverley SM, Zhang K, Keyel PA. The sphingolipids ceramide and inositol phosphorylceramide protect the Leishmania major membrane from sterol-specific toxins. J Biol Chem 2023; 299:104745. [PMID: 37094699 PMCID: PMC10209034 DOI: 10.1016/j.jbc.2023.104745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 04/19/2023] [Accepted: 04/21/2023] [Indexed: 04/26/2023] Open
Abstract
The accessibility of sterols in mammalian cells to exogenous sterol-binding agents has been well-described previously, but sterol accessibility in distantly related protozoa is unclear. The human pathogen Leishmania major uses sterols and sphingolipids distinct from those used in mammals. Sterols in mammalian cells can be sheltered from sterol-binding agents by membrane components, including sphingolipids, but the surface exposure of ergosterol in Leishmania remains unknown. Here, we used flow cytometry to test the ability of the Leishmania major sphingolipids inositol phosphorylceramide (IPC), and ceramide to shelter ergosterol by preventing binding of the sterol-specific toxins streptolysin O and perfringolysin O and subsequent cytotoxicity. In contrast to mammalian systems, we found that Leishmania sphingolipids did not preclude toxin binding to sterols in the membrane. However, we show that IPC reduced cytotoxicity, and that ceramide reduced perfringolysin O-, but not streptolysin O-, mediated cytotoxicity in cells. Furthermore, we demonstrate ceramide sensing was controlled by the toxin L3 loop, and that ceramide was sufficient to protect L. major promastigotes from the anti-leishmaniasis drug amphotericin B. Based on these results, we propose a mechanism whereby pore-forming toxins engage additional lipids like ceramide to determine the optimal environment to sustain pore formation. Thus, L. major could serve as a genetically tractable protozoan model organism for understanding toxin-membrane interactions.
Collapse
Affiliation(s)
- Chaitanya S Haram
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - Samrat Moitra
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - Rilee Keane
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - F Matthew Kuhlmann
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Cheryl Frankfater
- Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Stephen M Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409
| | - Peter A Keyel
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409.
| |
Collapse
|
6
|
Couves EC, Gardner S, Voisin TB, Bickel JK, Stansfeld PJ, Tate EW, Bubeck D. Structural basis for membrane attack complex inhibition by CD59. Nat Commun 2023; 14:890. [PMID: 36797260 PMCID: PMC9935631 DOI: 10.1038/s41467-023-36441-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/01/2023] [Indexed: 02/18/2023] Open
Abstract
CD59 is an abundant immuno-regulatory receptor that protects human cells from damage during complement activation. Here we show how the receptor binds complement proteins C8 and C9 at the membrane to prevent insertion and polymerization of membrane attack complex (MAC) pores. We present cryo-electron microscopy structures of two inhibited MAC precursors known as C5b8 and C5b9. We discover that in both complexes, CD59 binds the pore-forming β-hairpins of C8 to form an intermolecular β-sheet that prevents membrane perforation. While bound to C8, CD59 deflects the cascading C9 β-hairpins, rerouting their trajectory into the membrane. Preventing insertion of C9 restricts structural transitions of subsequent monomers and indirectly halts MAC polymerization. We combine our structural data with cellular assays and molecular dynamics simulations to explain how the membrane environment impacts the dual roles of CD59 in controlling pore formation of MAC, and as a target of bacterial virulence factors which hijack CD59 to lyse human cells.
Collapse
Affiliation(s)
- Emma C Couves
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Scott Gardner
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Tomas B Voisin
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Jasmine K Bickel
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, United Kingdom
| | - Phillip J Stansfeld
- School of Life Sciences and Department of Chemistry, Gibbet Hill Campus, The University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Edward W Tate
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, United Kingdom
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, United Kingdom.
| |
Collapse
|
7
|
Liu N, Wang X, Shan Q, Li S, Li Y, Chu B, Wang J, Zhu Y. Single Point Mutation and Its Role in Specific Pathogenicity to Reveal the Mechanism of Related Protein Families. Microbiol Spectr 2022; 10:e0092322. [PMID: 36214694 PMCID: PMC9603606 DOI: 10.1128/spectrum.00923-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 09/21/2022] [Indexed: 12/30/2022] Open
Abstract
Pyolysin (PLO) is secreted by Trueperella pyogenes as a water-soluble monomer after forming transmembrane β-barrel channels in the cell membrane by binding cholesterol. Two significantly conserved residues at domain 1 of PLO are mutated, which provides novel evidence of a relationship between conformational change and interaction with the cell membrane and uncovers the pore formation mechanism of the cholesterol-dependent cytolysin (CDC) family. Moreover, PLO is a special member of the CDCs, which the percentage of sequence identities between PLO and other CDC members is from 31% to 45%, while others are usually from 40% to 70%. It is important to understand that at very low sequence identities, models can be different in the pathogenic mechanisms of these CDC members, which are dedicated to a large number of Gram-positive bacterial pathogens. Our studies, for the first time, located and mutated two different highly conserved structural sites in the primary structure critical for PLO structure and function that proved the importance of these sites. Together, novel and repeatable observations into the pore formation mechanism of CDCs are provided by our findings. IMPORTANCE Postpartum disease of dairy cows caused by persistent bacterial infection is a global disease, which has a serious impact on the development of the dairy industry and brings huge economic losses. As one of the most relevant pathogenic bacteria for postpartum diseases in dairy cows, Trueperella pyogenes can secrete pyolysin (PLO), a member of the cholesterol-dependent cytolysin (CDC) family and recognized as the most important toxin of T. pyogenes. However, the current research work on PLO is still insufficient. The pathogenic mechanism of this toxin can be fully explored by changing the local structure and overall function of the toxin by a previously unidentified single point mutation. These studies lay the groundwork for future studies that will explore the contribution of this large family of CDC proteins to microbial survival and human disease.
Collapse
Affiliation(s)
- Ning Liu
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xue Wang
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Qiang Shan
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Shuxian Li
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yanan Li
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Bingxin Chu
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jiufeng Wang
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yaohong Zhu
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| |
Collapse
|
8
|
Membrane Cholesterol Content and Lipid Organization Influence Melittin and Pneumolysin Pore-Forming Activity. Toxins (Basel) 2022; 14:toxins14050346. [PMID: 35622592 PMCID: PMC9147762 DOI: 10.3390/toxins14050346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 12/12/2022] Open
Abstract
Melittin, the main toxic component in the venom of the European honeybee, interacts with natural and artificial membranes due to its amphiphilic properties. Rather than interacting with a specific receptor, melittin interacts with the lipid components, disrupting the lipid bilayer and inducing ion leakage and osmotic shock. This mechanism of action is shared with pneumolysin and other members of the cholesterol-dependent cytolysin family. In this manuscript, we investigated the inverse correlation for cholesterol dependency of these two toxins. While pneumolysin-induced damage is reduced by pretreatment with the cholesterol-depleting agent methyl-β-cyclodextrin, the toxicity of melittin, after cholesterol depletion, increased. A similar response was also observed after a short incubation with lipophilic simvastatin, which alters membrane lipid organization and structure, clustering lipid rafts. Therefore, changes in toxin sensitivity can be achieved in cells by depleting cholesterol or changing the lipid bilayer organization.
Collapse
|
9
|
Ormsby TJR, Owens SE, Clement L, Mills TJ, Cronin JG, Bromfield JJ, Sheldon IM. Oxysterols Protect Epithelial Cells Against Pore-Forming Toxins. Front Immunol 2022; 13:815775. [PMID: 35154132 PMCID: PMC8825411 DOI: 10.3389/fimmu.2022.815775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/05/2022] [Indexed: 12/25/2022] Open
Abstract
Many species of bacteria produce toxins such as cholesterol-dependent cytolysins that form pores in cell membranes. Membrane pores facilitate infection by releasing nutrients, delivering virulence factors, and causing lytic cell damage - cytolysis. Oxysterols are oxidized forms of cholesterol that regulate cellular cholesterol and alter immune responses to bacteria. Whether oxysterols also influence the protection of cells against pore-forming toxins is unresolved. Here we tested the hypothesis that oxysterols stimulate the intrinsic protection of epithelial cells against damage caused by cholesterol-dependent cytolysins. We treated epithelial cells with oxysterols and then challenged them with the cholesterol-dependent cytolysin, pyolysin. Treating HeLa cells with 27-hydroxycholesterol, 25-hydroxycholesterol, 7α-hydroxycholesterol, or 7β-hydroxycholesterol reduced pyolysin-induced leakage of lactate dehydrogenase and reduced pyolysin-induced cytolysis. Specifically, treatment with 10 ng/ml 27-hydroxycholesterol for 24 h reduced pyolysin-induced lactate dehydrogenase leakage by 88%, and reduced cytolysis from 74% to 1%. Treating HeLa cells with 27-hydroxycholesterol also reduced pyolysin-induced leakage of potassium ions, prevented mitogen-activated protein kinase cell stress responses, and limited alterations in the cytoskeleton. Furthermore, 27-hydroxycholesterol reduced pyolysin-induced damage in lung and liver epithelial cells, and protected against the cytolysins streptolysin O and Staphylococcus aureus α-hemolysin. Although oxysterols regulate cellular cholesterol by activating liver X receptors, cytoprotection did not depend on liver X receptors or changes in total cellular cholesterol. However, oxysterol cytoprotection was partially dependent on acyl-CoA:cholesterol acyltransferase (ACAT) reducing accessible cholesterol in cell membranes. Collectively, these findings imply that oxysterols stimulate the intrinsic protection of epithelial cells against pore-forming toxins and may help protect tissues against pathogenic bacteria.
Collapse
Affiliation(s)
- Thomas J R Ormsby
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - Sian E Owens
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - Liam Clement
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - Tom J Mills
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - James G Cronin
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| | - John J Bromfield
- Department of Animal Sciences, University of Florida, Gainesville, FL, United States
| | - Iain Martin Sheldon
- Swansea University Medical School, Swansea University, Swansea, United Kingdom
| |
Collapse
|
10
|
Xie J, Meng Z, Han X, Li S, Ma X, Chen X, Liang Y, Deng X, Xia K, Zhang Y, Zhu H, Fu T. Cholesterol Microdomain Enhances the Biofilm Eradication of Antibiotic Liposomes. Adv Healthc Mater 2022; 11:e2101745. [PMID: 35037424 DOI: 10.1002/adhm.202101745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 01/09/2022] [Indexed: 11/06/2022]
Abstract
Resistance and tolerance of biofilms to antibiotics is the greatest challenge in the treatment of bacterial infections. Therefore, developing an effective strategy against biofilms is a top priority. Liposomes are widely used as antibiotic drug carriers; however, common liposomes lack affinity for biofilms. Herein, biofilm-targeted antibiotic liposomes are created by simply adjusting their cholesterol content. The tailored liposomes exhibit significantly enhanced bacterial inhibition and biofilm eradication effects that are positively correlated with the cholesterol content of liposomes. The experiments further demonstrate that this enhanced effect can be ascribed to the effective drug release through the pores, which are formed by the combination of cholesterol microdomains in liposomal lipid bilayers with membrane-damaged toxins in biofilms. Consequently, liposome encapsulation with a high cholesterol concentration improves noticeably the pharmacodynamics and biocompatibility of antibiotics after pulmonary administration. This work may provide a new direction for the development of antibiofilm formulations that can be widely used for the treatment of infections caused by bacterial biofilms.
Collapse
Affiliation(s)
- Jianjun Xie
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Zhiping Meng
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Xingxing Han
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Sipan Li
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Xinai Ma
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Xuanyu Chen
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Yinmei Liang
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Xiaomin Deng
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Kexin Xia
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Yue Zhang
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Huaxu Zhu
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Tingming Fu
- School of Pharmacy Nanjing University of Chinese Medicine Nanjing 210023 China
| |
Collapse
|
11
|
Lata K, Singh M, Chatterjee S, Chattopadhyay K. Membrane Dynamics and Remodelling in Response to the Action of the Membrane-Damaging Pore-Forming Toxins. J Membr Biol 2022; 255:161-173. [PMID: 35305136 DOI: 10.1007/s00232-022-00227-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 03/02/2022] [Indexed: 12/11/2022]
Abstract
Pore-forming protein toxins (PFTs) represent a diverse class of membrane-damaging proteins that are produced by a wide variety of organisms. PFT-mediated membrane perforation is largely governed by the chemical composition and the physical properties of the plasma membranes. The interaction between the PFTs with the target membranes is critical for the initiation of the pore-formation process, and can lead to discrete membrane reorganization events that further aids in the process of pore-formation. Punching holes on the plasma membranes by the PFTs interferes with the cellular homeostasis by disrupting the ion-balance inside the cells that in turn can turn on multiple signalling cascades required to restore membrane integrity and cellular homeostasis. In this review, we discuss the physicochemical attributes of the plasma membranes associated with the pore-formation processes by the PFTs, and the subsequent membrane remodelling events that may start off the membrane-repair mechanisms.
Collapse
Affiliation(s)
- Kusum Lata
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Mahendra Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Shamaita Chatterjee
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali, Punjab, 140306, India.
| |
Collapse
|
12
|
Tabata A, Nagamune H. Diversity of β-hemolysins produced by the human opportunistic streptococci. Microbiol Immunol 2021; 65:512-529. [PMID: 34591320 DOI: 10.1111/1348-0421.12936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 11/28/2022]
Abstract
The genus Streptococcus infects a broad range of hosts, including humans. Some species, such as S. pyogenes, S. agalactiae, S. pneumoniae, and S. mutans, are recognized as the major human pathogens, and their pathogenicity toward humans has been investigated. However, many of other streptococcal species have been recognized as opportunistic pathogens in humans, and their clinical importance has been underestimated. In our previous study, the Anginosus group streptococci (AGS) and Mitis group streptococci (MGS) showed clear β-hemolysis on blood agar, and the factors responsible for the hemolysis were homologs of two types of β-hemolysins, cholesterol-dependent cytolysin (CDC) and streptolysin S (SLS). In contrast to the regular β-hemolysins produced by streptococci (typical CDCs and SLSs), genetically, structurally, and functionally atypical β-hemolysins have been observed in AGS and MGS. These atypical β-hemolysins are thought to affect and contribute to the pathogenic potential of opportunistic streptococci mainly inhabiting the human oral cavity. In this review, we introduce the diverse characteristics of β-hemolysin produced by opportunistic streptococci, focusing on the species/strains belonging to AGS and MGS, and discuss their pathogenic potential.
Collapse
Affiliation(s)
- Atsushi Tabata
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Hideaki Nagamune
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University Graduate School, Tokushima, Japan
| |
Collapse
|
13
|
Mondal AK, Chattopadhyay K. Structures and functions of the membrane-damaging pore-forming proteins. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:241-288. [PMID: 35034720 DOI: 10.1016/bs.apcsb.2021.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pore-forming proteins (PFPs) of the diverse life forms have emerged as the potent cell-killing entities owing to their specialized membrane-damaging properties. PFPs have the unique ability to perforate the plasma membranes of their target cells, and they exert this functionality by creating oligomeric pores in the membrane lipid bilayer. Pathogenic bacteria employ PFPs as toxins to execute their virulence mechanisms, whereas in the higher vertebrates PFPs are deployed as the part of the immune system and to generate inflammatory responses. PFPs are the unique dimorphic proteins that are generally synthesized as water-soluble molecules, and transform into membrane-inserted oligomeric pore assemblies upon interacting with the target membranes. In spite of sharing very little sequence similarity, PFPs from diverse organisms display incredible structural similarity. Yet, at the same time, structure-function mechanisms of the PFPs document remarkable versatility. Such notions establish PFPs as the fascinating model system to explore variety of unsolved issues pertaining to the structure-function paradigm of the proteins that interact and act in the membrane environment. In this article, we discuss our current understanding regarding the structural basis of the pore-forming functions of the diverse class of PFPs. We attempt to highlight the similarities and differences in their structures, membrane pore-formation mechanisms, and their implications for the various biological processes, ranging from the bacterial virulence mechanisms to the inflammatory immune response generation in the higher animals.
Collapse
Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
| |
Collapse
|
14
|
Pospiech M, Owens SE, Miller DJ, Austin-Muttitt K, Mullins JGL, Cronin JG, Allemann RK, Sheldon IM. Bisphosphonate inhibitors of squalene synthase protect cells against cholesterol-dependent cytolysins. FASEB J 2021; 35:e21640. [PMID: 33991130 DOI: 10.1096/fj.202100164r] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/09/2021] [Accepted: 04/19/2021] [Indexed: 01/29/2023]
Abstract
Certain species of pathogenic bacteria damage tissues by secreting cholesterol-dependent cytolysins, which form pores in the plasma membranes of animal cells. However, reducing cholesterol protects cells against these cytolysins. As the first committed step of cholesterol biosynthesis is catalyzed by squalene synthase, we explored whether inhibiting this enzyme protected cells against cholesterol-dependent cytolysins. We first synthesized 22 different nitrogen-containing bisphosphonate molecules that were designed to inhibit squalene synthase. Squalene synthase inhibition was quantified using a cell-free enzyme assay, and validated by computer modeling of bisphosphonate molecules binding to squalene synthase. The bisphosphonates were then screened for their ability to protect HeLa cells against the damage caused by the cholesterol-dependent cytolysin, pyolysin. The most effective bisphosphonate reduced pyolysin-induced leakage of lactate dehydrogenase into cell supernatants by >80%, and reduced pyolysin-induced cytolysis from >75% to <25%. In addition, this bisphosphonate reduced pyolysin-induced leakage of potassium from cells, limited changes in the cytoskeleton, prevented mitogen-activated protein kinases cell stress responses, and reduced cellular cholesterol. The bisphosphonate also protected cells against another cholesterol-dependent cytolysin, streptolysin O, and protected lung epithelial cells and primary dermal fibroblasts against cytolysis. Our findings imply that treatment with bisphosphonates that inhibit squalene synthase might help protect tissues against pathogenic bacteria that secrete cholesterol-dependent cytolysins.
Collapse
Affiliation(s)
- Mateusz Pospiech
- Swansea University Medical School, Swansea University, Swansea, UK
| | - Siân E Owens
- Swansea University Medical School, Swansea University, Swansea, UK
| | | | | | | | - James G Cronin
- Swansea University Medical School, Swansea University, Swansea, UK
| | | | - I Martin Sheldon
- Swansea University Medical School, Swansea University, Swansea, UK
| |
Collapse
|
15
|
Draberova L, Tumova M, Draber P. Molecular Mechanisms of Mast Cell Activation by Cholesterol-Dependent Cytolysins. Front Immunol 2021; 12:670205. [PMID: 34248949 PMCID: PMC8260682 DOI: 10.3389/fimmu.2021.670205] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 06/08/2021] [Indexed: 12/23/2022] Open
Abstract
Mast cells are potent immune sensors of the tissue microenvironment. Within seconds of activation, they release various preformed biologically active products and initiate the process of de novo synthesis of cytokines, chemokines, and other inflammatory mediators. This process is regulated at multiple levels. Besides the extensively studied IgE and IgG receptors, toll-like receptors, MRGPR, and other protein receptor signaling pathways, there is a critical activation pathway based on cholesterol-dependent, pore-forming cytolytic exotoxins produced by Gram-positive bacterial pathogens. This pathway is initiated by binding the exotoxins to the cholesterol-rich membrane, followed by their dimerization, multimerization, pre-pore formation, and pore formation. At low sublytic concentrations, the exotoxins induce mast cell activation, including degranulation, intracellular calcium concentration changes, and transcriptional activation, resulting in production of cytokines and other inflammatory mediators. Higher toxin concentrations lead to cell death. Similar activation events are observed when mast cells are exposed to sublytic concentrations of saponins or some other compounds interfering with the membrane integrity. We review the molecular mechanisms of mast cell activation by pore-forming bacterial exotoxins, and other compounds inducing cholesterol-dependent plasma membrane perturbations. We discuss the importance of these signaling pathways in innate and acquired immunity.
Collapse
Affiliation(s)
- Lubica Draberova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Magda Tumova
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Petr Draber
- Department of Signal Transduction, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| |
Collapse
|
16
|
Vaginal Isolates of Candida glabrata Are Uniquely Susceptible to Ionophoric Killer Toxins Produced by Saccharomyces cerevisiae. Antimicrob Agents Chemother 2021; 65:e0245020. [PMID: 33972245 PMCID: PMC8218651 DOI: 10.1128/aac.02450-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Compared to other species of Candida yeasts, the growth of Candida glabrata is inhibited by many different strains of Saccharomyces killer yeasts. The ionophoric K1 and K2 killer toxins are broadly inhibitory to all clinical isolates of C. glabrata from patients with recurrent vulvovaginal candidiasis, despite high levels of resistance to clinically relevant antifungal therapeutics.
Collapse
|
17
|
Hernández-Castañeda MA, Lavergne M, Casanova P, Nydegger B, Merten C, Subramanian BY, Matthey P, Lannes N, Mantel PY, Walch M. A Profound Membrane Reorganization Defines Susceptibility of Plasmodium falciparum Infected Red Blood Cells to Lysis by Granulysin and Perforin. Front Immunol 2021; 12:643746. [PMID: 34093532 PMCID: PMC8170093 DOI: 10.3389/fimmu.2021.643746] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 04/26/2021] [Indexed: 01/11/2023] Open
Abstract
Malaria remains one of the most serious health problems in developing countries. The causative agent of malaria, Plasmodium spp., have a complex life cycle involving multiple developmental stages as well as different morphological, biochemical and metabolic requirements. We recently found that γδ T cells control parasite growth using pore-forming proteins to deliver their cytotoxic proteases, the granzymes, into blood residing parasites. Here, we follow up on the molecular mechanisms of parasite growth inhibition by human pore-forming proteins. We confirm that Plasmodium falciparum infection efficiently depletes the red blood cells of cholesterol, which renders the parasite surrounding membranes susceptible to lysis by prokaryotic membrane disrupting proteins, such as lymphocytic granulysin or the human cathelicidin LL-37. Interestingly, not the cholesterol depletion but rather the simultaneous exposure of phosphatidylserine, a negatively charged phospholipid, triggers resistance of late stage parasitized red blood cells towards the eukaryotic pore forming protein perforin. Overall, by revealing the molecular events we establish here a pathogen-host interaction that involves host cell membrane remodeling that defines the susceptibility towards cytolytic molecules.
Collapse
Affiliation(s)
- Maria Andrea Hernández-Castañeda
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Marilyne Lavergne
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Pierina Casanova
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Bryan Nydegger
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Carla Merten
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Bibin Yesodha Subramanian
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Patricia Matthey
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Nils Lannes
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Pierre-Yves Mantel
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Michael Walch
- Department of Oncology, Microbiology and Immunology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| |
Collapse
|
18
|
Liposomes Prevent In Vitro Hemolysis Induced by Streptolysin O and Lysenin. MEMBRANES 2021; 11:membranes11050364. [PMID: 34069894 PMCID: PMC8157566 DOI: 10.3390/membranes11050364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/08/2021] [Accepted: 05/12/2021] [Indexed: 12/12/2022]
Abstract
The need for alternatives to antibiotics in the fight against infectious diseases has inspired scientists to focus on antivirulence factors instead of the microorganisms themselves. In this respect, prior work indicates that tiny, enclosed bilayer lipid membranes (liposomes) have the potential to compete with cellular targets for toxin binding, hence preventing their biological attack and aiding with their clearance. The effectiveness of liposomes as decoy targets depends on their availability in the host and how rapidly they are cleared from the circulation. Although liposome PEGylation may improve their circulation time, little is known about how such a modification influences their interactions with antivirulence factors. To fill this gap in knowledge, we investigated regular and long-circulating liposomes for their ability to prevent in vitro red blood cell hemolysis induced by two potent lytic toxins, lysenin and streptolysin O. Our explorations indicate that both regular and long-circulating liposomes are capable of similarly preventing lysis induced by streptolysin O. In contrast, PEGylation reduced the effectiveness against lysenin-induced hemolysis and altered binding dynamics. These results suggest that toxin removal by long-circulating liposomes is feasible, yet dependent on the particular virulence factor under scrutiny.
Collapse
|
19
|
Parperis C, Wallace MI. Single-molecule imaging of pore-forming toxin dynamics in droplet interface bilayers. Methods Enzymol 2021; 649:431-459. [PMID: 33712195 DOI: 10.1016/bs.mie.2021.01.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Single-channel recording from pore-forming toxins (PFTs) provides a clear and direct molecular readout of toxin action. However to complete any mechanistic understanding of PFT behavior, this functional kinetic readout must be linked to the underlying changes in toxin structure, binding, conformation, or stoichiometry. Here we review how single-molecule imaging methods might be used to further our understanding of PFTs, and provide detailed practical guidance on the use of droplet interface bilayers as a method capable of examining both single-molecule fluorescence and single-channel electrical signals from PFTs.
Collapse
Affiliation(s)
- Christopher Parperis
- Department of Chemistry, Britannia House, King's College London, London, United Kingdom
| | - Mark I Wallace
- Department of Chemistry, Britannia House, King's College London, London, United Kingdom.
| |
Collapse
|
20
|
Drabavicius G, Daelemans D. Intermedilysin cytolytic activity depends on heparan sulfates and membrane composition. PLoS Genet 2021; 17:e1009387. [PMID: 33577603 PMCID: PMC7906465 DOI: 10.1371/journal.pgen.1009387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 02/25/2021] [Accepted: 01/27/2021] [Indexed: 12/26/2022] Open
Abstract
Cholesterol-dependent cytolysins (CDCs), of which intermedilysin (ILY) is an archetypal member, are a group of pore-forming toxins secreted by a large variety of pathogenic bacteria. These toxins, secreted as soluble monomers, oligomerize upon interaction with cholesterol in the target membrane and transect it as pores of diameters of up to 100 to 300 Å. These pores disrupt cell membranes and result in cell lysis. The immune receptor CD59 is a well-established cellular factor required for intermedilysin pore formation. In this study, we applied genome-wide CRISPR-Cas9 knock-out screening to reveal additional cellular co-factors essential for ILY-mediated cell lysis. We discovered a plethora of genes previously not associated with ILY, many of which are important for membrane constitution. We show that heparan sulfates facilitate ILY activity, which can be inhibited by heparin. Furthermore, we identified hits in both protein and lipid glycosylation pathways and show a role for glucosylceramide, demonstrating that membrane organization is important for ILY activity. We also cross-validated identified genes with vaginolysin and pneumolysin and found that pneumolysin's cytolytic activity strongly depends on the asymmetric distribution of membrane phospholipids. This study shows that membrane-targeting toxins combined with genetic screening can identify genes involved in biological membrane composition and metabolism.
Collapse
Affiliation(s)
- Gediminas Drabavicius
- KU Leuven Department of Microbiology, Immunology, and Transplantation, Laboratory of Virology and Chemotherapy, Rega Institute, Leuven, Belgium
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Vilnius, Lithuania
| | - Dirk Daelemans
- KU Leuven Department of Microbiology, Immunology, and Transplantation, Laboratory of Virology and Chemotherapy, Rega Institute, Leuven, Belgium
- * E-mail:
| |
Collapse
|
21
|
Functional and Structural Variation among Sticholysins, Pore-Forming Proteins from the Sea Anemone Stichodactyla helianthus. Int J Mol Sci 2020; 21:ijms21238915. [PMID: 33255441 PMCID: PMC7727798 DOI: 10.3390/ijms21238915] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 12/15/2022] Open
Abstract
Venoms constitute complex mixtures of many different molecules arising from evolution in processes driven by continuous prey-predator interactions. One of the most common compounds in these venomous cocktails are pore-forming proteins, a family of toxins whose activity relies on the disruption of the plasmatic membranes by forming pores. The venom of sea anemones, belonging to the oldest lineage of venomous animals, contains a large amount of a characteristic group of pore-forming proteins known as actinoporins. They bind specifically to sphingomyelin-containing membranes and suffer a conformational metamorphosis that drives them to make pores. This event usually leads cells to death by osmotic shock. Sticholysins are the actinoporins produced by Stichodactyla helianthus. Three different isotoxins are known: Sticholysins I, II, and III. They share very similar amino acid sequence and three-dimensional structure but display different behavior in terms of lytic activity and ability to interact with cholesterol, an important lipid component of vertebrate membranes. In addition, sticholysins can act in synergy when exerting their toxin action. The subtle, but important, molecular nuances that explain their different behavior are described and discussed throughout the text. Improving our knowledge about sticholysins behavior is important for eventually developing them into biotechnological tools.
Collapse
|
22
|
Phelps CC, Vadia S, Boyaka PN, Varikuti S, Attia Z, Dubey P, Satoskar AR, Tweten R, Seveau S. A listeriolysin O subunit vaccine is protective against Listeria monocytogenes. Vaccine 2020; 38:5803-5813. [PMID: 32684498 DOI: 10.1016/j.vaccine.2020.06.049] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 05/12/2020] [Accepted: 06/18/2020] [Indexed: 12/15/2022]
Abstract
Listeria monocytogenes is a facultative intracellular pathogen responsible for the life-threatening disease listeriosis. The pore-forming toxin listeriolysin O (LLO) is a critical virulence factor that plays a major role in the L. monocytogenes intracellular lifecycle and is indispensable for pathogenesis. LLO is also a dominant antigen for T cells involved in sterilizing immunity and it was proposed that LLO acts as a T cell adjuvant. In this work, we generated a novel full-length LLO toxoid (LLOT) in which the cholesterol-recognition motif, a threonine-leucine pair located at the tip of the LLO C-terminal domain, was substituted with two glycine residues. We showed that LLOT lost its ability to bind cholesterol and to form pores. Importantly, LLOT retained binding to the surface of epithelial cells and macrophages, suggesting that it could efficiently be captured by antigen-presenting cells. We then determined if LLOT can be used as an antigen and adjuvant to protect mice from L. monocytogenes infection. Mice were immunized with LLOT alone or together with cholera toxin or Alum as adjuvants. We found that mice immunized with LLOT alone or in combination with the Th2-inducing adjuvant Alum were not protected against L. monocytogenes. On the other hand, mice immunized with LLOT along with the experimental adjuvant cholera toxin, were protected against L. monocytogenes, as evidenced by a significant decrease in bacterial burden in the liver and spleen three days post-infection. This immunization regimen elicited mixed Th1, Th2, and Th17 responses, as well as the generation of LLO-neutralizing antibodies. Further, we identified T cells as being required for immunization-induced reductions in bacterial burden, whereas B cells were dispensable in our model of non-pregnant young mice. Overall, this work establishes that LLOT is a promising vaccine antigen for the induction of protective immunity against L. monocytogenes by subunit vaccines containing Th1-driving adjuvants.
Collapse
Affiliation(s)
- Christopher C Phelps
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA; Department of Microbiology, The Ohio State University, The Ohio State University, Columbus, OH, USA
| | - Stephen Vadia
- Department of Microbiology, The Ohio State University, The Ohio State University, Columbus, OH, USA; Department of Biology, Washington University in St. Louis, MO 63130, USA
| | - Prosper N Boyaka
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA; Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Sanjay Varikuti
- Department of Pathology, The Ohio State University, Columbus, OH, USA
| | - Zayed Attia
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Purnima Dubey
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Abhay R Satoskar
- Department of Pathology, The Ohio State University, Columbus, OH, USA
| | - Rodney Tweten
- Department of Microbial & Immunology, University of Oklahoma, Oklahoma City, OK, USA
| | - Stephanie Seveau
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA; Department of Microbiology, The Ohio State University, The Ohio State University, Columbus, OH, USA.
| |
Collapse
|
23
|
Glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins from pathogenic bacteria. PLoS One 2020; 15:e0219275. [PMID: 32163417 PMCID: PMC7067430 DOI: 10.1371/journal.pone.0219275] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 02/21/2020] [Indexed: 12/28/2022] Open
Abstract
Pathogenic bacteria often damage tissues by secreting toxins that form pores in cell membranes, and the most common pore-forming toxins are cholesterol-dependent cytolysins. During bacterial infections, glutamine becomes a conditionally essential amino acid, and glutamine is an important nutrient for immune cells. However, the role of glutamine in protecting tissue cells against pore-forming toxins is unclear. Here we tested the hypothesis that glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins. Stromal and epithelial cells were sensitive to damage by the cholesterol-dependent cytolysins, pyolysin and streptolysin O, as determined by leakage of potassium and lactate dehydrogenase from cells, and reduced cell viability. However, glutamine deprivation increased the leakage of lactate dehydrogenase and reduced the viability of cells challenged with cholesterol-dependent cytolysins. Without glutamine, stromal cells challenged with pyolysin leaked lactate dehydrogenase (control vs. pyolysin, 2.6 ± 0.6 vs. 34.4 ± 4.5 AU, n = 12), which was more than three-fold the leakage from cells supplied with 2 mM glutamine (control vs. pyolysin, 2.2 ± 0.3 vs. 9.4 ± 1.0 AU). Glutamine cytoprotection did not depend on glutaminolysis, replenishing the Krebs cycle via succinate, changes in cellular cholesterol, or regulators of cell metabolism (AMPK and mTOR). In conclusion, although the mechanism remains elusive, we found that glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins from pathogenic bacteria.
Collapse
|
24
|
Vötsch D, Willenborg M, Oelemann WM, Brogden G, Valentin-Weigand P. Membrane Binding, Cellular Cholesterol Content and Resealing Capacity Contribute to Epithelial Cell Damage Induced by Suilysin of Streptococcus suis. Pathogens 2019; 9:pathogens9010033. [PMID: 31905867 PMCID: PMC7168673 DOI: 10.3390/pathogens9010033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/19/2019] [Accepted: 12/24/2019] [Indexed: 12/31/2022] Open
Abstract
Streptococcus (S.) suis is a major cause of economic losses in the pig industry worldwide and is an emerging zoonotic pathogen. One important virulence-associated factor is suilysin (SLY), a toxin that belongs to the family of cholesterol-dependent pore-forming cytolysins (CDC). However, the precise role of SLY in host–pathogen interactions is still unclear. Here, we investigated the susceptibility of different respiratory epithelial cells to SLY, including immortalized cell lines (HEp-2 and NPTr cells), which are frequently used in in vitro studies on S. suis virulence mechanisms, as well as primary porcine respiratory cells, which represent the first line of barrier during S. suis infections. SLY-induced cell damage was determined by measuring the release of lactate dehydrogenase after infection with a virulent S. suis serotype 2 strain, its isogenic SLY-deficient mutant strain, or treatment with the recombinant protein. HEp-2 cells were most susceptible, whereas primary epithelial cells were hardly affected by the toxin. This prompted us to study possible explanations for these differences. We first investigated the binding capacity of SLY using flow cytometry analysis. Since binding and pore-formation of CDC is dependent on the membrane composition, we also determined the cellular cholesterol content of the different cell types using TLC and HPLC. Finally, we examined the ability of those cells to reseal SLY-induced pores using flow cytometry analysis. Our results indicated that the amount of membrane-bound SLY, the cholesterol content of the cells, as well as their resealing capacity all affect the susceptibility of the different cells regarding the effects of SLY. These findings underline the differences of in vitro pathogenicity models and may further help to dissect the biological role of SLY during S. suis infections.
Collapse
Affiliation(s)
- Désirée Vötsch
- Institute for Microbiology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany; (D.V.); (M.W.)
| | - Maren Willenborg
- Institute for Microbiology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany; (D.V.); (M.W.)
| | - Walter M.R. Oelemann
- Institute for Microbiology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany; (D.V.); (M.W.)
- Departamento de Imunologia, Instituto de Microbiologia Paulo Góes, Universidade Federal do Rio de Janeiro (UFRJ), 21941-901 Rio de Janeiro, Brazil
| | - Graham Brogden
- Department of Physiological Chemistry, University for Veterinary Medicine Hannover, 30559 Hannover, Germany;
| | - Peter Valentin-Weigand
- Institute for Microbiology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany; (D.V.); (M.W.)
- Correspondence: ; Tel.: +49-(0)511-856-7362
| |
Collapse
|
25
|
Lamb CL, Price E, Field KP, Dayton C, McIndoo ER, Katahira EJ, Stevens DL, Hobdey SE. Enrichment of Antigen-Specific Class-Switched B Cells from Individuals Naturally Immunized by Infection with Group A Streptococcus. mSphere 2019; 4:e00598-19. [PMID: 31694896 PMCID: PMC6835209 DOI: 10.1128/msphere.00598-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/17/2019] [Indexed: 01/17/2023] Open
Abstract
The low frequency of circulating antigen-specific memory B cells is a considerable obstacle in the discovery and development of human monoclonal antibodies for therapeutic application. Here, we evaluate two solid-phase isolation methods to enrich the number of antigen-specific B cells from individuals naturally immunized against streptolysin O (SLO), a key virulence factor and known immunogen of group A streptococcus (GAS). Class-switched B cells obtained from individuals with a history of GAS infection were separated from peripheral blood mononuclear cells (PBMCs) by immunomagnetic methods. SLO-specific B cells were further enriched directly by binding to SLO monomers and captured by streptavidin-coated magnetic microbeads or indirectly by binding a fluorescently labeled SLO-streptavidin tetramer and captured by anti-fluorophore immunomagnetic microbeads. SLO-bound B cells were quantitated by flow cytometry and/or expanded in batch culture to determine IgG specificity. From individuals who have suffered a GAS infection ≥2 years prior, only the direct method enriched SLO-specific B cells, as determined by flow cytometry. Likewise, in batch culture, B cells isolated by the direct method resulted in an average of 375-fold enrichment in anti-SLO IgG, while no enrichment was observed for B cells isolated by the indirect method. The direct method established here provides a simple approach to increase low-frequency antigen-specific B cell populations supporting many downstream applications, such as immortalization of B cells, cloning of immunoglobulin genes, or purification of antibodies from supernatant for future study. Overall, this process is efficient, is inexpensive, and can be applied to many naturally immunogenic antigens.IMPORTANCE Bacteria called group A streptococci can cause a variety of skin and soft tissue infections ranging from mild pharyngitis ("strep throat") to deadly necrotizing fasciitis (sometimes called "flesh-eating" disease). In each case, the development of disease and the degree of tissue damage are mediated by toxins released from the bacteria during infection. Consequently, novel therapies aimed at clearing bacterial toxins are greatly needed. One promising new treatment is the utilization of monoclonal antibodies delivered as an immunotherapeutic for toxin neutralization. However, current methods of antibody development are laborious and costly. Here, we report a method to enrich and increase the detection of highly desirable antigen-specific memory B cells from individuals previously exposed to GAS using a cost-effective and less-time-intensive strategy. We envision that this method will be incorporated into many applications supporting the development of immunotherapeutics.
Collapse
Affiliation(s)
- Cheri L Lamb
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Emily Price
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Kevin P Field
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Christopher Dayton
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| | - Eric R McIndoo
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
| | - Eva J Katahira
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
| | - Dennis L Stevens
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
- University of Washington School of Medicine, Seattle, Washington, USA
| | - Sarah E Hobdey
- Infectious Diseases Section, Veteran Affairs Medical Center, Boise, Idaho, USA
- Idaho Veterans Research and Education Foundation, Boise, Idaho, USA
| |
Collapse
|
26
|
Hilburger CE, Jacobs ML, Lewis KR, Peruzzi JA, Kamat NP. Controlling Secretion in Artificial Cells with a Membrane AND Gate. ACS Synth Biol 2019; 8:1224-1230. [PMID: 31051071 DOI: 10.1021/acssynbio.8b00435] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The assembly of channel proteins into vesicle membranes is a useful strategy to control activities of vesicle-based systems. Here, we developed a membrane AND gate that responds to both a fatty acid and a pore-forming channel protein to induce the release of encapsulated cargo. We explored how membrane composition affects the functional assembly of α-hemolysin into phospholipid vesicles as a function of oleic acid content and α-hemolysin concentration. We then showed that we could induce α-hemolysin assembly when we added oleic acid micelles to a specific composition of phospholipid vesicles. Finally, we demonstrated that our membrane AND gate could be coupled to a gene expression system. Our study provides a new method to control the temporal dynamics of vesicle permeability by controlling when the functional assembly of a channel protein into synthetic vesicles occurs. Furthermore, a membrane AND gate that utilizes membrane-associating biomolecules introduces a new way to implement Boolean logic that should complement genetic logic circuits and ultimately enhance the capabilities of artificial cellular systems.
Collapse
|
27
|
Abstract
Pneumolysin (PLY), a major virulence factor of Streptococcus pneumoniae, perforates cholesterol-rich lipid membranes. PLY protomers oligomerize as rings on the membrane and then undergo a structural transition that triggers the formation of membrane pores. Structures of PLY rings in prepore and pore conformations define the beginning and end of this transition, but the detailed mechanism of pore formation remains unclear. With atomistic and coarse-grained molecular dynamics simulations, we resolve key steps during PLY pore formation. Our simulations confirm critical PLY membrane-binding sites identified previously by mutagenesis. The transmembrane β-hairpins of the PLY pore conformation are stable only for oligomers, forming a curtain-like membrane-spanning β-sheet. Its hydrophilic inner face draws water into the protein-lipid interface, forcing lipids to recede. For PLY rings, this zone of lipid clearance expands into a cylindrical membrane pore. The lipid plug caught inside the PLY ring can escape by lipid efflux via the lower leaflet. If this path is too slow or blocked, the pore opens by membrane buckling, driven by the line tension acting on the detached rim of the lipid plug. Interestingly, PLY rings are just wide enough for the plug to buckle spontaneously in mammalian membranes. In a survey of electron cryo-microscopy (cryo-EM) and atomic force microscopy images, we identify key intermediates along both the efflux and buckling pathways to pore formation, as seen in the simulations.
Collapse
|
28
|
Ray S, Thapa R, Keyel PA. Multiple Parameters Beyond Lipid Binding Affinity Drive Cytotoxicity of Cholesterol-Dependent Cytolysins. Toxins (Basel) 2018; 11:toxins11010001. [PMID: 30577571 PMCID: PMC6356533 DOI: 10.3390/toxins11010001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 02/06/2023] Open
Abstract
The largest superfamily of bacterial virulence factors is pore-forming toxins (PFTs). PFTs are secreted by both pathogenic and non-pathogenic bacteria. PFTs sometimes kill or induce pro-pathogen signaling in mammalian cells, all primarily through plasma membrane perforation, though the parameters that determine these outcomes are unclear. Membrane binding, calcium influx, pore size, and membrane repair are factors that influence PFT cytotoxicity. To test the contribution of membrane binding to cytotoxicity and repair, we compared the closely related, similarly-sized PFTs Perfringolysin O (PFO) from Clostridium perfringens and Streptolysin O (SLO) from Streptococcus pyogenes. Cell death kinetics for PFO and SLO were different because PFO increased in cytotoxicity over time. We introduced known L3 loop mutations that swap binding affinity between toxins and measured hemolytic activity, nucleated cell death kinetics and membrane repair using viability assays, and live cell imaging. Altered hemolytic activity was directly proportional to toxin binding affinity. In contrast, L3 loop alterations reduced nucleated cell death, and they had limited effects on cytotoxicity kinetics and membrane repair. This suggests other toxin structural features, like oligomerization, drives these parameters. Overall, these findings suggest that repair mechanisms and toxin oligomerization add constraints beyond membrane binding on toxin evolution and activity against nucleated cells.
Collapse
Affiliation(s)
- Sucharit Ray
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409, USA.
| | - Roshan Thapa
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409, USA.
| | - Peter A Keyel
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409, USA.
| |
Collapse
|
29
|
Zhang W, Wang H, Wang B, Zhang Y, Hu Y, Ma B, Wang J. Replacing the 238th aspartic acid with an arginine impaired the oligomerization activity and inflammation-inducing property of pyolysin. Virulence 2018; 9:1112-1125. [PMID: 30067143 PMCID: PMC6086297 DOI: 10.1080/21505594.2018.1491256] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Trueperella pyogenes (T. pyogenes) is an important opportunistic pathogen. Pyolysin (PLO) importantly contributes to the pathogenicity of T. pyogenes. However, the relationship between the structure and function and the virulence of PLO is not well documented. In the current study, recombinant PLO (rPLO) and three rPLO mutants were prepared. rPLO D238R, a mutant with the 238th aspartic acid replaced with an arginine, showed impairment in oligomerization activity on cholesterol-containing liposome and pore-forming activity on sheep red blood cell membrane. Further study employing the prepared mutants confirmed that the pore-forming activity of PLO is essential for inducing excessive inflammation responses in mice by upregulating the expression levels of IL-1β, TNF-α, and IL-6. By contrast, rPLO P499F, another mutant with impaired cell membrane binding capacity, elicited an inflammation response that was dependent on pathogen-associated molecular pattern (PAMP) activity, given that the mutant significantly upregulated the expression of IL-10 in macrophages and in mice, whereas rPLO did not. Results indicated that domain 1 of the PLO molecule plays an important role in maintaining pore-forming activity. Moreover, the PLO pore-forming activity and not PAMP activity is responsible for the inflammation-inducing effect of PLO. The results of this study provided new information for research field on the structure, function, and virulence of PLO. Abbreviations: T. pyogenes: Trueperella pyogenes; PLO: Pyolysin; rPLO: recombinant PLO; PAMP: pathogen-associated molecular pattern; CDCs: cholesterol-dependent cytolysins; PLY: pneumolysin; NLRP3: NLR family pyrin domain containing protein 3; PRRs: pattern recognition receptors; Asp: aspartic acid; TLR4: Toll-like receptor 4; Arg: arginine; Asn: asparagine; IPTG: Isopropyl-β-d-thiogalactoside; PBS: phosphate-buffered saline; sRBCs: sheep red blood cells; TEM: Transmission electron microscopy; RBCM: red blood cell membrane; SDS-PAGE: sodium dodecyl sulfate–polyacrylamide gel electrophoresis; NC membrane: nitrocellulose membrane; SDS-AGE: dodecyl sulfate agarose gel electrophoresis; MDBK cells: Madin–Darby bovine kidney cells; RPMI-1640 medium: Roswell Park Memorial Institute-1640 medium; FBS: fetal bovine serum; BMDMs: bone marrow-derived macrophages; TNF-α: tumor necrosis factor α; IL-1β: interleukin-1β; IFN-γ: interferon-γ; TGF-β: transforming growth factor-β; ELISA: enzyme-linked immunosorbent assay
Collapse
Affiliation(s)
- Wenlong Zhang
- a College of Veterinary Medicine , Northeast Agricultural University , Harbin , PR China.,b China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology , Northeastern Science Inspection Station , Harbin , PR China
| | - Haili Wang
- a College of Veterinary Medicine , Northeast Agricultural University , Harbin , PR China.,b China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology , Northeastern Science Inspection Station , Harbin , PR China
| | - Bing Wang
- a College of Veterinary Medicine , Northeast Agricultural University , Harbin , PR China.,b China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology , Northeastern Science Inspection Station , Harbin , PR China
| | - Yue Zhang
- a College of Veterinary Medicine , Northeast Agricultural University , Harbin , PR China.,b China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology , Northeastern Science Inspection Station , Harbin , PR China
| | - Yunhao Hu
- a College of Veterinary Medicine , Northeast Agricultural University , Harbin , PR China.,b China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology , Northeastern Science Inspection Station , Harbin , PR China
| | - Bo Ma
- a College of Veterinary Medicine , Northeast Agricultural University , Harbin , PR China.,b China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology , Northeastern Science Inspection Station , Harbin , PR China
| | - Junwei Wang
- a College of Veterinary Medicine , Northeast Agricultural University , Harbin , PR China.,b China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology , Northeastern Science Inspection Station , Harbin , PR China
| |
Collapse
|
30
|
Revisiting the role of cholesterol in regulating the pore-formation mechanism of Vibrio cholerae cytolysin, a membrane-damaging β-barrel pore-forming toxin. Biochem J 2018; 475:3039-3055. [DOI: 10.1042/bcj20180387] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/03/2018] [Accepted: 09/10/2018] [Indexed: 11/17/2022]
Abstract
Vibrio cholerae cytolysin (VCC) is a β-barrel pore-forming toxin with potent membrane-damaging cell-killing activity. Previous studies employing the model membranes of lipid vesicles (liposomes) have shown that pore formation by VCC requires the presence of cholesterol in the liposome membranes. However, the exact role of cholesterol in the mode of action of VCC still remains unclear. Most importantly, implication of cholesterol, if any, in regulating the pore-formation mechanism of VCC in the biomembranes of eukaryotic cells remains unexplored. Here, we show that the presence of cholesterol promotes the interaction of VCC with the membrane lipid bilayer, when non-lipid-dependent interactions are absent. However, in the case of biomembranes of human erythrocytes, where accessory interactions are available, cholesterol appears to play a less critical role in the binding step. Nevertheless, in the absence of an optimal level of membrane cholesterol in the human erythrocytes, membrane-bound fraction of the toxin remains trapped in the form of abortive oligomeric assembly, devoid of functional pore-forming activity. Our study also shows that VCC exhibits a prominent propensity to associate with the cholesterol-rich membrane micro-domains of human erythrocytes. Interestingly, mutation of the cholesterol-binding ability of VCC does not block association with the cholesterol-rich membrane micro-domains on human erythrocytes. Based on these results, we propose that the specific cholesterol-binding ability of VCC does not appear to dictate its association with the cholesterol-rich micro-domains on human erythrocytes. Rather, targeting of VCC toward the membrane micro-domains of human erythrocytes possibly acts to facilitate the cholesterol-dependent pore-formation mechanism of the toxin.
Collapse
|
31
|
Cholesterol promotes Cytolysin A activity by stabilizing the intermediates during pore formation. Proc Natl Acad Sci U S A 2018; 115:E7323-E7330. [PMID: 30012608 DOI: 10.1073/pnas.1721228115] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Pore-forming toxins (PFTs) form nanoscale pores across target membranes causing cell death. Cytolysin A (ClyA) from Escherichia coli is a prototypical α-helical toxin that contributes to cytolytic phenotype of several pathogenic strains. It is produced as a monomer and, upon membrane exposure, undergoes conformational changes and finally oligomerizes to form a dodecameric pore, thereby causing ion imbalance and finally cell death. However, our current understanding of this assembly process is limited to studies in detergents, which do not capture the physicochemical properties of biological membranes. Here, using single-molecule imaging and molecular dynamics simulations, we study the ClyA assembly pathway on phospholipid bilayers. We report that cholesterol stimulates pore formation, not by enhancing initial ClyA binding to the membrane but by selectively stabilizing a protomer-like conformation. This was mediated by specific interactions by cholesterol-interacting residues in the N-terminal helix. Additionally, cholesterol stabilized the oligomeric structure using bridging interactions in the protomer-protomer interfaces, thereby resulting in enhanced ClyA oligomerization. This dual stabilization of distinct intermediates by cholesterol suggests a possible molecular mechanism by which ClyA achieves selective membrane rupture of eukaryotic cell membranes. Topological similarity to eukaryotic membrane proteins suggests evolution of a bacterial α-toxin to adopt eukaryotic motifs for its activation. Broad mechanistic correspondence between pore-forming toxins hints at a wider prevalence of similar protein membrane insertion mechanisms.
Collapse
|
32
|
Sarangi NK, Basu JK. Pathways for creation and annihilation of nanoscale biomembrane domains reveal alpha and beta-toxin nanopore formation processes. Phys Chem Chem Phys 2018; 20:29116-29130. [DOI: 10.1039/c8cp05729j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Raft-like functional domains with putative sizes of 20–200 nm and which are evolving dynamically are believed to be the most crucial regions in cellular membranes which determine cell signaling and various functions of cells.
Collapse
Affiliation(s)
| | - Jaydeep Kumar Basu
- Department of Physics
- Indian Institute of Science
- Bangalore – 560 012
- India
| |
Collapse
|
33
|
Griffin S, Preta G, Sheldon IM. Inhibiting mevalonate pathway enzymes increases stromal cell resilience to a cholesterol-dependent cytolysin. Sci Rep 2017; 7:17050. [PMID: 29213055 PMCID: PMC5719056 DOI: 10.1038/s41598-017-17138-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/22/2017] [Indexed: 01/28/2023] Open
Abstract
Animal health depends on the ability of immune cells to kill invading pathogens, and on the resilience of tissues to tolerate the presence of pathogens. Trueperella pyogenes causes tissue pathology in many mammals by secreting a cholesterol-dependent cytolysin, pyolysin (PLO), which targets stromal cells. Cellular cholesterol is derived from squalene, which is synthesized via the mevalonate pathway enzymes, including HMGCR, FDPS and FDFT1. The present study tested the hypothesis that inhibiting enzymes in the mevalonate pathway to reduce cellular cholesterol increases the resilience of stromal cells to PLO. We first verified that depleting cellular cholesterol with methyl-β-cyclodextrin increased the resilience of stromal cells to PLO. We then used siRNA to deplete mevalonate pathway enzyme gene expression, and used pharmaceutical inhibitors, atorvastatin, alendronate or zaragozic acid to inhibit the activity of HMGCR, FDPS and FDFT1, respectively. These approaches successfully reduced cellular cholesterol abundance, but mevalonate pathway enzymes did not affect cellular resilience equally. Inhibiting FDFT1 was most effective, with zaragozic acid reducing the impact of PLO on cell viability. The present study provides evidence that inhibiting FDFT1 increases stromal cell resilience to a cholesterol-dependent cytolysin.
Collapse
Affiliation(s)
- Sholeem Griffin
- Swansea University Medical School, Swansea University, Swansea, SA2 8PP, United Kingdom
| | - Giulio Preta
- Swansea University Medical School, Swansea University, Swansea, SA2 8PP, United Kingdom.,Institute of Biochemistry, Vilnius University, Sauletekio 7, Vilnius LT-10257, Lithuania
| | - Iain Martin Sheldon
- Swansea University Medical School, Swansea University, Swansea, SA2 8PP, United Kingdom.
| |
Collapse
|
34
|
Interaction of Cholesterol with Perfringolysin O: What Have We Learned from Functional Analysis? Toxins (Basel) 2017; 9:toxins9120381. [PMID: 29168745 PMCID: PMC5744101 DOI: 10.3390/toxins9120381] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/16/2017] [Accepted: 11/17/2017] [Indexed: 12/27/2022] Open
Abstract
Cholesterol-dependent cytolysins (CDCs) constitute a family of pore-forming toxins secreted by Gram-positive bacteria. These toxins form transmembrane pores by inserting a large β-barrel into cholesterol-containing membranes. Cholesterol is absolutely required for pore-formation. For most CDCs, binding to cholesterol triggers conformational changes that lead to oligomerization and end in pore-formation. Perfringolysin O (PFO), secreted by Clostridium perfringens, is the prototype for the CDCs. The molecular mechanisms by which cholesterol regulates the cytolytic activity of the CDCs are not fully understood. In particular, the location of the binding site for cholesterol has remained elusive. We have summarized here the current body of knowledge on the CDCs-cholesterol interaction, with focus on PFO. We have employed sterols in aqueous solution to identify structural elements in the cholesterol molecule that are critical for its interaction with PFO. In the absence of high-resolution structural information, site-directed mutagenesis data combined with binding studies performed with different sterols, and molecular modeling are beginning to shed light on this interaction.
Collapse
|
35
|
Danesh Mesgaran S, Gärtner MA, Wagener K, Drillich M, Ehling-Schulz M, Einspanier R, Gabler C. Different inflammatory responses of bovine oviductal epithelial cells in vitro to bacterial species with distinct pathogenicity characteristics and passage number. Theriogenology 2017; 106:237-246. [PMID: 29096271 DOI: 10.1016/j.theriogenology.2017.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 09/05/2017] [Accepted: 10/03/2017] [Indexed: 12/24/2022]
Abstract
The bovine oviduct provides the site for fertilization and early embryonic development. Modifications to this physiological environment, for instance the presence of pathogenic bacterial species, could diminish reproductive success at early stages of pregnancy. The aim of this study was to elucidate the inflammatory responses of bovine oviductal epithelial cells (BOEC) to a pathogenic bacterial species (Trueperella pyogenes) and a potentially pathogenic bacterium (Bacillus pumilus). BOEC from four healthy animals were isolated, cultured in passage 0 (P0) and passaged until P3. Trypan blue staining determined BOEC viability during 24 h co-culture with different multiplicities of infection (MOI) of T. pyogenes (MOI 0.01, 0.05, 0.1 and 1) or B. pumilus (MOI 1 and 10). BOEC remained viable when co-cultured with T. pyogenes at MOI 0.01 and with B. pumilus at MOI 1 and 10. Extracted total RNA from control and bacteria co-cultured samples was subjected to reverse transcription-quantitative polymerase chain reaction (RTq-PCR) to determine mRNA expression of various studied genes. The rate of release of interleukin 8 (IL8) and prostaglandin E2 (PGE2) from BOEC was measured by ELISA after 24 h co-culture with bacteria. RT-qPCR of various selected pro-inflammatory factors revealed similar mRNA expression of pro-inflammatory factors in BOEC co-cultured with T. pyogenes and in the controls. Higher mRNA expression of IL 1A, -1B, tumor necrosis factor alpha and CXC ligand (CXCL) 1/2, -3, -5 and IL8 and PG synthesis enzymes in BOEC co-cultured with B. pumilus was observed. In the presence of B. pumilus a higher amount of IL8 and PGE2 was released from BOEC than from controls. The viability and pro-inflammatory response of P3 BOEC incubated with bacteria was lower than in P0 BOEC. These findings illustrate the pathogenicity of T. pyogenes towards BOEC in detail and the potential role of B. pumilus in generating inflammation in oviductal cells. Culturing conditions influenced the pro-inflammatory responses of BOEC towards bacteria. Therefore, researchers conducting epithelial-bacterial in vitro co-culture should not underestimate the effects of these parameters.
Collapse
Affiliation(s)
- S Danesh Mesgaran
- Institute of Veterinary Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - M A Gärtner
- Institute of Veterinary Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - K Wagener
- University Clinic for Ruminants, Clinical Unit for Herd Health Management in Ruminants, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria; Institute of Microbiology, Functional Microbiology, Department for Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - M Drillich
- University Clinic for Ruminants, Clinical Unit for Herd Health Management in Ruminants, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
| | - M Ehling-Schulz
- Institute of Microbiology, Functional Microbiology, Department for Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - R Einspanier
- Institute of Veterinary Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - C Gabler
- Institute of Veterinary Biochemistry, Freie Universität Berlin, Berlin, Germany.
| |
Collapse
|
36
|
Malabed R, Hanashima S, Murata M, Sakurai K. Sterol-recognition ability and membrane-disrupting activity of Ornithogalum saponin OSW-1 and usual 3-O-glycosyl saponins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2516-2525. [PMID: 28947142 DOI: 10.1016/j.bbamem.2017.09.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/05/2017] [Accepted: 09/18/2017] [Indexed: 12/14/2022]
Abstract
OSW-1 is a structurally unique steroidal saponin isolated from the bulbs of Ornithogalum saundersiae, and has exhibited highly potent and selective cytotoxicity in tumor cell lines. This study aimed to investigate the molecular mechanism for the membrane-permeabilizing activity of OSW-1 in comparison with those of other saponins by using various spectroscopic approaches. The membrane effects and hemolytic activity of OSW-1 were markedly enhanced in the presence of membrane cholesterol. Binding affinity measurements using fluorescent cholestatrienol and solid-state NMR spectroscopy of a 3-d-cholesterol probe suggested that OSW-1 interacts with membrane cholesterol without forming large aggregates while 3-O-glycosyl saponin, digitonin, forms cholesterol-containing aggregates. The results suggest that OSW-1/cholesterol interaction is likely to cause membrane permeabilization and pore formation without destroying the whole membrane integrity, which could partly be responsible for its highly potent cell toxicity.
Collapse
Affiliation(s)
- Raymond Malabed
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
| | - Kaori Sakurai
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588, Japan
| |
Collapse
|
37
|
Yang L, Zhang Y, Wang H, Ma B, Xu L, Wang J, Zhang W. Identification of B-cell linear epitopes in domains 1-3 of pyolysin of Trueperella pyogenes using polyclonal antibodies. Vet Microbiol 2017; 210:24-31. [PMID: 29103692 DOI: 10.1016/j.vetmic.2017.08.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/23/2017] [Accepted: 08/26/2017] [Indexed: 11/17/2022]
Abstract
Trueperella pyogenes is an important opportunistic pathogen. Pyolysin (PLO) makes important contributions to the pathogenicity of T. pyogenes. However, the structure and function of PLO has not been well documented. In the current study, epitopes in domain 1-3 of PLO have been mapped using rabbit anti-recombinant PLO (rPLO) polyclonal antibodies, and then the results were re-checked by using mouse and chicken anti-rPLO polyclonal antibodies, respectively. The results indicated that the region of aa 281-393 in PLO could not elicit antibodies against linear epitopes. A total of six B cell linear epitopes have been found in domain 1 of PLO. Two of the six epitopes (EP1 and EP2) were used to immunize mice and chicken. Chicken anti-EP1 and anti-EP2 serum and mouse anti-EP2 serum could react with rPLO and corresponding epitope polypeptide in western blot assay; however, only mouse anti-EP2 serum shows weak anti-hemolysis effect in the rPLO and sheep red blood system. Our results provide some new information to the research field of PLO structure and function.
Collapse
Affiliation(s)
- Lingxiao Yang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology, PR China
| | - Yue Zhang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology, PR China
| | - Haili Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology, PR China
| | - Bo Ma
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology, PR China
| | - Li Xu
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China
| | - Junwei Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology, PR China.
| | - Wenlong Zhang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen Biology, PR China; College of Animal Science and Technology, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China.
| |
Collapse
|
38
|
Intrinsic repair protects cells from pore-forming toxins by microvesicle shedding. Cell Death Differ 2017; 24:798-808. [PMID: 28186501 DOI: 10.1038/cdd.2017.11] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 12/13/2016] [Accepted: 01/17/2017] [Indexed: 01/01/2023] Open
Abstract
Pore-forming toxins (PFTs) are used by both the immune system and by pathogens to disrupt cell membranes. Cells attempt to repair this disruption in various ways, but the exact mechanism(s) that cells use are not fully understood, nor agreed upon. Current models for membrane repair include (1) patch formation (e.g., fusion of internal vesicles with plasma membrane defects), (2) endocytosis of the pores, and (3) shedding of the pores by blebbing from the cell membrane. In this study, we sought to determine the specific mechanism(s) that cells use to resist three different cholesterol-dependent PFTs: Streptolysin O, Perfringolysin O, and Intermedilysin. We found that all three toxins were shed from cells by blebbing from the cell membrane on extracellular microvesicles (MVs). Unique among the cells studied, we found that macrophages were 10 times more resistant to the toxins, yet they shed significantly smaller vesicles than the other cells. To examine the mechanism of shedding, we tested whether toxins with engineered defects in pore formation or oligomerization were shed. We found that oligomerization was necessary and sufficient for membrane shedding, suggesting that calcium influx and patch formation were not required for shedding. However, pore formation enhanced shedding, suggesting that calcium influx and patch formation enhance repair. In contrast, monomeric toxins were endocytosed. These data indicate that cells use two interrelated mechanisms of membrane repair: lipid-dependent MV shedding, which we term 'intrinsic repair', and patch formation by intracellular organelles. Endocytosis may act after membrane repair is complete by removing inactivated and monomeric toxins from the cell surface.
Collapse
|
39
|
Al Khamici H, Hossain KR, Cornell BA, Valenzuela SM. Investigating Sterol and Redox Regulation of the Ion Channel Activity of CLIC1 Using Tethered Bilayer Membranes. MEMBRANES 2016; 6:membranes6040051. [PMID: 27941637 PMCID: PMC5192407 DOI: 10.3390/membranes6040051] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/04/2016] [Accepted: 12/05/2016] [Indexed: 12/03/2022]
Abstract
The Chloride Intracellular Ion Channel (CLIC) family consists of six conserved proteins in humans. These are a group of enigmatic proteins, which adopt both a soluble and membrane bound form. CLIC1 was found to be a metamorphic protein, where under specific environmental triggers it adopts more than one stable reversible soluble structural conformation. CLIC1 was found to spontaneously insert into cell membranes and form chloride ion channels. However, factors that control the structural transition of CLIC1 from being an aqueous soluble protein into a membrane bound protein have yet to be adequately described. Using tethered bilayer lipid membranes and electrical impedance spectroscopy system, herein we demonstrate that CLIC1 ion channel activity is dependent on the type and concentration of sterols in bilayer membranes. These findings suggest that membrane sterols play an essential role in CLIC1’s acrobatic switching from a globular soluble form to an integral membrane form, promoting greater ion channel conductance in membranes. What remains unclear is the precise nature of this regulation involving membrane sterols and ultimately determining CLIC1’s membrane structure and function as an ion channel. Furthermore, our impedance spectroscopy results obtained using CLIC1 mutants, suggest that the residue Cys24 is not essential for CLIC1’s ion channel function. However Cys24 does appear important for optimal ion channel activity. We also observe differences in conductance between CLIC1 reduced and oxidized forms when added to our tethered membranes. Therefore, we conclude that both membrane sterols and redox play a role in the ion channel activity of CLIC1.
Collapse
Affiliation(s)
- Heba Al Khamici
- School of Life Sciences, University of Technology Sydney, Sydney 2007, Australia.
| | - Khondher R Hossain
- School of Life Sciences, University of Technology Sydney, Sydney 2007, Australia.
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), NSW 2234, Australia.
| | | | - Stella M Valenzuela
- School of Life Sciences, University of Technology Sydney, Sydney 2007, Australia.
| |
Collapse
|
40
|
Boyd CM, Parsons ES, Smith RAG, Seddon JM, Ces O, Bubeck D. Disentangling the roles of cholesterol and CD59 in intermedilysin pore formation. Sci Rep 2016; 6:38446. [PMID: 27910935 PMCID: PMC5133593 DOI: 10.1038/srep38446] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/08/2016] [Indexed: 01/08/2023] Open
Abstract
The plasma membrane provides an essential barrier, shielding a cell from the pressures of its external environment. Pore-forming proteins, deployed by both hosts and pathogens alike, breach this barrier to lyse target cells. Intermedilysin is a cholesterol-dependent cytolysin that requires the human immune receptor CD59, in addition to cholesterol, to form giant β-barrel pores in host membranes. Here we integrate biochemical assays with electron microscopy and atomic force microscopy to distinguish the roles of these two receptors in mediating structural transitions of pore formation. CD59 is required for the specific coordination of intermedilysin (ILY) monomers and for triggering collapse of an oligomeric prepore. Movement of Domain 2 with respect to Domain 3 of ILY is essential for forming a late prepore intermediate that releases CD59, while the role of cholesterol may be limited to insertion of the transmembrane segments. Together these data define a structural timeline for ILY pore formation and suggest a mechanism that is relevant to understanding other pore-forming toxins that also require CD59.
Collapse
Affiliation(s)
- Courtney M. Boyd
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| | - Edward S. Parsons
- Department of Chemistry and Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
| | - Richard A. G. Smith
- MRC Centre for Transplantation, King’s College London, 5th Floor Tower Wing, Guys’ Hospital, London SE1 9RT, UK
| | - John M. Seddon
- Department of Chemistry and Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Oscar Ces
- Department of Chemistry and Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
41
|
Hermand P, Vandercammen A, Mertens E, Di Paolo E, Verlant V, Denoël P, Godfroid F. Preclinical evaluation of a chemically detoxified pneumolysin as pneumococcal vaccine antigen. Hum Vaccin Immunother 2016; 13:220-228. [PMID: 27768518 PMCID: PMC5287308 DOI: 10.1080/21645515.2016.1234553] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The use of protein antigens able to protect against the majority of Streptococcus pneumoniae serotypes is envisaged as stand-alone and/or complement to the current capsular polysaccharide-based pneumococcal vaccines. Pneumolysin (Ply) is a key virulence factor that is highly conserved in amino acid sequence across pneumococcal serotypes, and therefore may be considered as a vaccine target. However, native Ply cannot be used in vaccines due to its intrinsic cytolytic activity. In the present work a completely, irreversibly detoxified pneumolysin (dPly) has been generated using an optimized formaldehyde treatment. Detoxi-fication was confirmed by dPly challenge in mice and histological analysis of the injection site in rats. Immunization with dPly elicited Ply-specific functional antibodies that were able to inhibit Ply activity in a hemolysis assay. In addition, immunization with dPly protected mice against lethal intranasal challenge with Ply, and intranasal immunization inhibited nasopharyngeal colonization after intranasal challenge with homologous or heterologous pneumococcal strain. Our findings supported dPly as a valid candidate antigen for further pneumococcal vaccine development.
Collapse
|
42
|
Lawrence SL, Gorman MA, Feil SC, Mulhern TD, Kuiper MJ, Ratner AJ, Tweten RK, Morton CJ, Parker MW. Structural Basis for Receptor Recognition by the Human CD59-Responsive Cholesterol-Dependent Cytolysins. Structure 2016; 24:1488-98. [PMID: 27499440 PMCID: PMC5320943 DOI: 10.1016/j.str.2016.06.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 06/15/2016] [Accepted: 06/20/2016] [Indexed: 11/23/2022]
Abstract
Cholesterol-dependent cytolysins (CDCs) are a family of pore-forming toxins that punch holes in the outer membrane of eukaryotic cells. Cholesterol serves as the receptor, but a subclass of CDCs first binds to human CD59. Here we describe the crystal structures of vaginolysin and intermedilysin complexed to CD59. These studies, together with small-angle X-ray scattering, reveal that CD59 binds to each at different, though overlapping, sites, consistent with molecular dynamics simulations and binding studies. The CDC consensus undecapeptide motif, which for the CD59-responsive CDCs has a proline instead of a tryptophan in the motif, adopts a strikingly different conformation between the structures; our data suggest that the proline acts as a selectivity switch to ensure CD59-dependent CDCs bind their protein receptor first in preference to cholesterol. The structural data suggest a detailed model of how these water-soluble toxins assemble as prepores on the cell surface.
Collapse
Affiliation(s)
- Sara L Lawrence
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Michael A Gorman
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Susanne C Feil
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Terrence D Mulhern
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Michael J Kuiper
- Victorian Life Sciences Computation Initiative, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Adam J Ratner
- Departments of Pediatrics and Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Rodney K Tweten
- Department of Microbiology and Immunology, University of Oklahoma, Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Craig J Morton
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia
| | - Michael W Parker
- ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia; Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3010, Australia.
| |
Collapse
|
43
|
GsdmD p30 elicited by caspase-11 during pyroptosis forms pores in membranes. Proc Natl Acad Sci U S A 2016; 113:7858-63. [PMID: 27339137 DOI: 10.1073/pnas.1607769113] [Citation(s) in RCA: 640] [Impact Index Per Article: 80.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Gasdermin-D (GsdmD) is a critical mediator of innate immune defense because its cleavage by the inflammatory caspases 1, 4, 5, and 11 yields an N-terminal p30 fragment that induces pyroptosis, a death program important for the elimination of intracellular bacteria. Precisely how GsdmD p30 triggers pyroptosis has not been established. Here we show that human GsdmD p30 forms functional pores within membranes. When liberated from the corresponding C-terminal GsdmD p20 fragment in the presence of liposomes, GsdmD p30 localized to the lipid bilayer, whereas p20 remained in the aqueous environment. Within liposomes, p30 existed as higher-order oligomers and formed ring-like structures that were visualized by negative stain electron microscopy. These structures appeared within minutes of GsdmD cleavage and released Ca(2+) from preloaded liposomes. Consistent with GsdmD p30 favoring association with membranes, p30 was only detected in the membrane-containing fraction of immortalized macrophages after caspase-11 activation by lipopolysaccharide. We found that the mouse I105N/human I104N mutation, which has been shown to prevent macrophage pyroptosis, attenuated both cell killing by p30 in a 293T transient overexpression system and membrane permeabilization in vitro, suggesting that the mutants are actually hypomorphs, but must be above certain concentration to exhibit activity. Collectively, our data suggest that GsdmD p30 kills cells by forming pores that compromise the integrity of the cell membrane.
Collapse
|
44
|
Bokori-Brown M, Petrov PG, Khafaji MA, Mughal MK, Naylor CE, Shore AC, Gooding KM, Casanova F, Mitchell TJ, Titball RW, Winlove CP. Red Blood Cell Susceptibility to Pneumolysin: CORRELATION WITH MEMBRANE BIOCHEMICAL AND PHYSICAL PROPERTIES. J Biol Chem 2016; 291:10210-27. [PMID: 26984406 DOI: 10.1074/jbc.m115.691899] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Indexed: 12/20/2022] Open
Abstract
This study investigated the effect of the biochemical and biophysical properties of the plasma membrane as well as membrane morphology on the susceptibility of human red blood cells to the cholesterol-dependent cytolysin pneumolysin, a key virulence factor of Streptococcus pneumoniae, using single cell studies. We show a correlation between the physical properties of the membrane (bending rigidity and surface and dipole electrostatic potentials) and the susceptibility of red blood cells to pneumolysin-induced hemolysis. We demonstrate that biochemical modifications of the membrane induced by oxidative stress, lipid scrambling, and artificial cell aging modulate the cell response to the toxin. We provide evidence that the diversity of response to pneumolysin in diabetic red blood cells correlates with levels of glycated hemoglobin and that the mechanical properties of the red blood cell plasma membrane are altered in diabetes. Finally, we show that diabetic red blood cells are more resistant to pneumolysin and the related toxin perfringolysin O relative to healthy red blood cells. Taken together, these studies indicate that the diversity of cell response to pneumolysin within a population of human red blood cells is influenced by the biophysical and biochemical status of the plasma membrane and the chemical and/or oxidative stress pre-history of the cell.
Collapse
Affiliation(s)
- Monika Bokori-Brown
- From the College of Life and Environmental Sciences, School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom,
| | - Peter G Petrov
- the College of Engineering, Mathematics and Physical Sciences, School of Physics, University of Exeter, Exeter EX4 4QL, United Kingdom
| | - Mawya A Khafaji
- the College of Engineering, Mathematics and Physical Sciences, School of Physics, University of Exeter, Exeter EX4 4QL, United Kingdom
| | - Muhammad K Mughal
- the Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Claire E Naylor
- the Department of Biological Sciences, Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom
| | - Angela C Shore
- the Department of Diabetes and Vascular Medicine, University of Exeter Medical School, Barrack Road, Exeter EX2 5AX, United Kingdom, the National Institute for Health Research Exeter Clinical Research Facility, Royal Devon and Exeter National Health Service Foundation Trust, Exeter EX2 5DW, United Kingdom, and
| | - Kim M Gooding
- the Department of Diabetes and Vascular Medicine, University of Exeter Medical School, Barrack Road, Exeter EX2 5AX, United Kingdom, the National Institute for Health Research Exeter Clinical Research Facility, Royal Devon and Exeter National Health Service Foundation Trust, Exeter EX2 5DW, United Kingdom, and
| | - Francesco Casanova
- the Department of Diabetes and Vascular Medicine, University of Exeter Medical School, Barrack Road, Exeter EX2 5AX, United Kingdom, the National Institute for Health Research Exeter Clinical Research Facility, Royal Devon and Exeter National Health Service Foundation Trust, Exeter EX2 5DW, United Kingdom, and
| | - Tim J Mitchell
- the Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Richard W Titball
- From the College of Life and Environmental Sciences, School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - C Peter Winlove
- the College of Engineering, Mathematics and Physical Sciences, School of Physics, University of Exeter, Exeter EX4 4QL, United Kingdom
| |
Collapse
|
45
|
Sarangi NK, Ayappa KG, Visweswariah SS, Basu JK. Nanoscale dynamics of phospholipids reveals an optimal assembly mechanism of pore-forming proteins in bilayer membranes. Phys Chem Chem Phys 2016; 18:29935-29945. [DOI: 10.1039/c6cp04631b] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Using STED-FCS, we show that the fluidity of the membrane controls the induced dynamical heterogeneity in model membranes upon interacting with pore-forming toxins.
Collapse
Affiliation(s)
| | - K. G. Ayappa
- Department of Chemical Engineering
- Indian Institute of Science
- Bangalore 560 012
- India
- Centre for Biosystems Science and Engineering
| | - Sandhya. S. Visweswariah
- Centre for Biosystems Science and Engineering
- Indian Institute of Science
- Bangalore 560012
- India
- Department of Molecular Reproduction
| | | |
Collapse
|
46
|
Yan M, Hu Y, Bao J, Xiao Y, Zhang Y, Yang L, Wang J, Zhang W. Isoleucine 61 is important for the hemolytic activity of pyolysin of Trueperella pyogenes. Vet Microbiol 2015; 182:196-201. [PMID: 26711048 DOI: 10.1016/j.vetmic.2015.11.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/20/2015] [Accepted: 11/22/2015] [Indexed: 11/16/2022]
Abstract
Pyolysin (PLO) is a hemolysin secreted by Trueperella pyogenes (T. pyogenes) and is important for the pathogenicity of T. pyogenes. Oligomerization of PLO monomers is a critical step in the process of hemolysis. However, the mechanisms of intermolecular interaction of PLO monomers are still not clearly illuminated. In this study, two monoclonal antibodies (mAbs) against PLO, named AP-1A3 and AP-4F12, respectively, were generated firstly, of which AP-1A3 showed no or undetectable hemolysis inhibition activity against recombinant PLO (rPLO), whereas AP-4F12 could markedly inhibit the hemolytic activity of rPLO. Epitope mapping revealed that AP-1A3 recognized amino acid residues ranging from 64 to 79 of mature PLO (91-106 including the signal peptide), whereas AP-4F12 recognized amino acid residues ranging from 58 to 75 (85-102 including the signal peptide). Comparison of the amino acid sequence of two epitopes revealed that six amino acid residues ranging from 58 to 63 of PLO were associated with the hemolytic activity of PLO. Alanine scan showed that substitution of each amino acid ranging from 58 to 62 with alanine had apparent impact on the hemolytic activity of rPLO, especially for the substitution of isoleucine 61 which caused almost complete loss of hemolytic activity of rPLO. Our findings identified a region in PLO and an amino acid in that region might play important role in the process of oligomerization of PLO monomers.
Collapse
Affiliation(s)
- Minghui Yan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China
| | - Yunhao Hu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China
| | - Jun Bao
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; National Food Safety and Nutrition Collaborative Innovation Center, Wuxi, Jiangsu 214122, PR China
| | - Ya Xiao
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China
| | - Yue Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China
| | - Lingxiao Yang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China
| | - Junwei Wang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China; National Food Safety and Nutrition Collaborative Innovation Center, Wuxi, Jiangsu 214122, PR China.
| | - Wenlong Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, PR China.
| |
Collapse
|
47
|
Crystal structure of Streptococcus pneumoniae pneumolysin provides key insights into early steps of pore formation. Sci Rep 2015; 5:14352. [PMID: 26403197 PMCID: PMC4585913 DOI: 10.1038/srep14352] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 08/26/2015] [Indexed: 11/16/2022] Open
Abstract
Pore-forming proteins are weapons often used by bacterial pathogens to breach the membrane barrier of target cells. Despite their critical role in infection important structural aspects of the mechanism of how these proteins assemble into pores remain unknown. Streptococcus pneumoniae is the world’s leading cause of pneumonia, meningitis, bacteremia and otitis media. Pneumolysin (PLY) is a major virulence factor of S. pneumoniae and a target for both small molecule drug development and vaccines. PLY is a member of the cholesterol-dependent cytolysins (CDCs), a family of pore-forming toxins that form gigantic pores in cell membranes. Here we present the structure of PLY determined by X-ray crystallography and, in solution, by small-angle X-ray scattering. The crystal structure reveals PLY assembles as a linear oligomer that provides key structural insights into the poorly understood early monomer-monomer interactions of CDCs at the membrane surface.
Collapse
|
48
|
Mozola CC, Caparon MG. Dual modes of membrane binding direct pore formation by Streptolysin O. Mol Microbiol 2015; 97:1036-50. [PMID: 26059530 DOI: 10.1111/mmi.13085] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2015] [Indexed: 11/30/2022]
Abstract
Effector translocation is central to the virulence of many bacterial pathogens, including Streptococcus pyogenes, which utilizes the cholesterol-dependent cytolysin Streptolysin O (SLO) to translocate the NAD(+) glycohydrolase SPN into host cells during infection. SLO's translocation activity does not require host cell membrane cholesterol or pore formation by SLO, yet SLO does form pores during infection via a cholesterol-dependent mechanism. Although cholesterol was considered the primary receptor for SLO, SLO's membrane-binding domain also encodes a putative carbohydrate-binding site, implicating a potential glycan receptor in binding and pore formation. Analysis of carbohydrate-binding site SLO mutants and carbohydrate-defective cell lines revealed that glycan recognition is involved in SLO's pore formation pathway and is an essential step when SLO is secreted by non-adherent bacteria, as occurs during lysis of erythrocytes. However, SLO also recognizes host cell membranes via a second mechanism when secreted from adherent bacteria, which requires co-secretion of SPN but not glycan binding by SLO. This SPN-mediated membrane binding of SLO correlates with SPN translocation, and requires SPN's non-enzymatic domain, which is predicted to adopt the structure of a carbohydrate-binding module. SPN-dependent membrane binding also promotes pore formation by SLO, demonstrating that pore formation can occur by distinct pathways during infection.
Collapse
Affiliation(s)
- Cara C Mozola
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO, 63110-1093, USA
| | - Michael G Caparon
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO, 63110-1093, USA
| |
Collapse
|
49
|
Farrand AJ, Hotze EM, Sato TK, Wade KR, Wimley WC, Johnson AE, Tweten RK. The Cholesterol-dependent Cytolysin Membrane-binding Interface Discriminates Lipid Environments of Cholesterol to Support β-Barrel Pore Insertion. J Biol Chem 2015; 290:17733-17744. [PMID: 26032415 DOI: 10.1074/jbc.m115.656769] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Indexed: 12/25/2022] Open
Abstract
The majority of cholesterol-dependent cytolysins (CDCs) utilize cholesterol as a membrane receptor, whereas a small number are restricted to the GPI-anchored protein CD59 for initial membrane recognition. Two cholesterol-binding CDCs, perfringolysin O (PFO) and streptolysin O (SLO), were found to exhibit strikingly different binding properties to cholesterol-rich natural and synthetic membranes. The structural basis for this difference was mapped to one of the loops (L3) in the membrane binding interface that help anchor the toxin monomers to the membrane after receptor (cholesterol) binding by the membrane insertion of its amino acid side chains. A single point mutation in this loop conferred the binding properties of SLO to PFO and vice versa. Our studies strongly suggest that changing the side chain structure of this loop alters its equilibrium between membrane-inserted and uninserted states, thereby affecting the overall binding affinity and total bound toxin. Previous studies have shown that the lipid environment of cholesterol has a dramatic effect on binding and activity. Combining this data with the results of our current studies on L3 suggests that the structure of this loop has evolved in the different CDCs to preferentially direct binding to cholesterol in different lipid environments. Finally, the efficiency of β-barrel pore formation was inversely correlated with the increased binding and affinity of the PFO L3 mutant, suggesting that selection of a compatible lipid environment impacts the efficiency of membrane insertion of the β-barrel pore.
Collapse
Affiliation(s)
- Allison J Farrand
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Eileen M Hotze
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Takehiro K Sato
- Departments of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843
| | - Kristin R Wade
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - William C Wimley
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, Louisiana 70112
| | - Arthur E Johnson
- Departments of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843; Departments of Chemistry and Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Rodney K Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
| |
Collapse
|
50
|
Perfringolysin O: The Underrated Clostridium perfringens Toxin? Toxins (Basel) 2015; 7:1702-21. [PMID: 26008232 PMCID: PMC4448169 DOI: 10.3390/toxins7051702] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 05/08/2015] [Indexed: 12/21/2022] Open
Abstract
The anaerobic bacterium Clostridium perfringens expresses multiple toxins that promote disease development in both humans and animals. One such toxin is perfringolysin O (PFO, classically referred to as θ toxin), a pore-forming cholesterol-dependent cytolysin (CDC). PFO is secreted as a water-soluble monomer that recognizes and binds membranes via cholesterol. Membrane-bound monomers undergo structural changes that culminate in the formation of an oligomerized prepore complex on the membrane surface. The prepore then undergoes conversion into the bilayer-spanning pore measuring approximately 250–300 Å in diameter. PFO is expressed in nearly all identified C. perfringens strains and harbors interesting traits that suggest a potential undefined role for PFO in disease development. Research has demonstrated a role for PFO in gas gangrene progression and bovine necrohemorrhagic enteritis, but there is limited data available to determine if PFO also functions in additional disease presentations caused by C. perfringens. This review summarizes the known structural and functional characteristics of PFO, while highlighting recent insights into the potential contributions of PFO to disease pathogenesis.
Collapse
|