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Shen Q, Xiong Q, Zhou K, Feng Q, Liu L, Tian T, Wu C, Xiong Y, Melia TJ, Lusk CP, Lin C. Functionalized DNA-Origami-Protein Nanopores Generate Large Transmembrane Channels with Programmable Size-Selectivity. J Am Chem Soc 2023; 145:1292-1300. [PMID: 36577119 PMCID: PMC9852090 DOI: 10.1021/jacs.2c11226] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The DNA-origami technique has enabled the engineering of transmembrane nanopores with programmable size and functionality, showing promise in building biosensors and synthetic cells. However, it remains challenging to build large (>10 nm), functionalizable nanopores that spontaneously perforate lipid membranes. Here, we take advantage of pneumolysin (PLY), a bacterial toxin that potently forms wide ring-like channels on cell membranes, to construct hybrid DNA-protein nanopores. This PLY-DNA-origami complex, in which a DNA-origami ring corrals up to 48 copies of PLY, targets the cholesterol-rich membranes of liposomes and red blood cells, readily forming uniformly sized pores with an average inner diameter of ∼22 nm. Such hybrid nanopores facilitate the exchange of macromolecules between perforated liposomes and their environment, with the exchange rate negatively correlating with the macromolecule size (diameters of gyration: 8-22 nm). Additionally, the DNA ring can be decorated with intrinsically disordered nucleoporins to further restrict the diffusion of traversing molecules, highlighting the programmability of the hybrid nanopores. PLY-DNA pores provide an enabling biophysical tool for studying the cross-membrane translocation of ultralarge molecules and open new opportunities for analytical chemistry, synthetic biology, and nanomedicine.
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Affiliation(s)
- Qi Shen
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
- Nanobiology Institute, Yale University, 850 West Campus Drive, West Haven, Connecticut 06516, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06511, United States
| | - Qiancheng Xiong
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
- Nanobiology Institute, Yale University, 850 West Campus Drive, West Haven, Connecticut 06516, United States
| | - Kaifeng Zhou
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06511, United States
| | - Qingzhou Feng
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
- Nanobiology Institute, Yale University, 850 West Campus Drive, West Haven, Connecticut 06516, United States
| | - Longfei Liu
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
- Nanobiology Institute, Yale University, 850 West Campus Drive, West Haven, Connecticut 06516, United States
| | - Taoran Tian
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
| | - Chunxiang Wu
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06511, United States
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, Connecticut 06511, United States
| | - Thomas J. Melia
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
| | - C. Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
| | - Chenxiang Lin
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, United States
- Nanobiology Institute, Yale University, 850 West Campus Drive, West Haven, Connecticut 06516, United States
- Department of Biomedical Engineering, Yale University, 17 Hillhouse Ave, New Haven, Connecticut 06511, United States
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The molecular mechanisms of listeriolysin O-induced lipid membrane damage. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183604. [PMID: 33722646 DOI: 10.1016/j.bbamem.2021.183604] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/05/2021] [Accepted: 03/05/2021] [Indexed: 12/22/2022]
Abstract
Listeria monocytogenes is an intracellular food-borne pathogen that causes listeriosis, a severe and potentially life-threatening disease. Listeria uses a number of virulence factors to proliferate and spread to various cells and tissues. In this process, three bacterial virulence factors, the pore-forming protein listeriolysin O and phospholipases PlcA and PlcB, play a crucial role. Listeriolysin O belongs to a family of cholesterol-dependent cytolysins that are mostly expressed by gram-positive bacteria. Its unique structural features in an otherwise conserved three-dimensional fold, such as the acidic triad and proline-glutamate-serine-threonine-like sequence, enable the regulation of its intracellular activity as well as distinct extracellular functions. The stability of listeriolysin O is pH- and temperature-dependent, and this provides another layer of control of its activity in cells. Moreover, many recent studies have demonstrated a unique mechanism of pore formation by listeriolysin O, i.e., the formation of arc-shaped oligomers that can subsequently fuse to form membrane defects of various shapes and sizes. During listerial invasion of host cells, these membrane defects can disrupt phagosome membranes, allowing bacteria to escape into the cytosol and rapidly multiply. The activity of listeriolysin O is profoundly dependent on the amount and accessibility of cholesterol in the lipid membrane, which can be modulated by the phospholipase PlcB. All these prominent features of listeriolysin O play a role during different stages of the L. monocytogenes life cycle by promoting the proliferation of the pathogen while mitigating excessive damage to its replicative niche in the cytosol of the host cell.
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Interaction of Macrophages and Cholesterol-Dependent Cytolysins: The Impact on Immune Response and Cellular Survival. Toxins (Basel) 2020; 12:toxins12090531. [PMID: 32825096 PMCID: PMC7551085 DOI: 10.3390/toxins12090531] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/13/2020] [Accepted: 08/15/2020] [Indexed: 02/07/2023] Open
Abstract
Cholesterol-dependent cytolysins (CDCs) are key virulence factors involved in many lethal bacterial infections, including pneumonia, necrotizing soft tissue infections, bacterial meningitis, and miscarriage. Host responses to these diseases involve myeloid cells, especially macrophages. Macrophages use several systems to detect and respond to cholesterol-dependent cytolysins, including membrane repair, mitogen-activated protein (MAP) kinase signaling, phagocytosis, cytokine production, and activation of the adaptive immune system. However, CDCs also promote immune evasion by silencing and/or destroying myeloid cells. While there are many common themes between the various CDCs, each CDC also possesses specific features to optimally benefit the pathogen producing it. This review highlights host responses to CDC pathogenesis with a focus on macrophages. Due to their robust plasticity, macrophages play key roles in the outcome of bacterial infections. Understanding the unique features and differences within the common theme of CDCs bolsters new tools for research and therapy.
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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.
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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
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5
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Kozorog M, Sani MA, Lenarčič Živković M, Ilc G, Hodnik V, Separovic F, Plavec J, Anderluh G. 19F NMR studies provide insights into lipid membrane interactions of listeriolysin O, a pore forming toxin from Listeria monocytogenes. Sci Rep 2018; 8:6894. [PMID: 29720597 PMCID: PMC5931962 DOI: 10.1038/s41598-018-24692-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/28/2018] [Indexed: 11/12/2022] Open
Abstract
Listeria monocytogenes is a mammalian pathogen that causes gastroenteritis, miscarriages and infections of the central nervous system in immunocompromised individuals. Its main virulence factor is listeriolysin O (LLO), a pore-forming cholesterol-dependent cytolysin (CDC), which enables bacterial escape from the phagolysosome and contributes to bacterial pathogenicity. Details of cholesterol (Chol) recognition and membrane binding mechanisms by LLO are still not known. Here we used 19F-NMR spectroscopy in order to assess LLO-Chol interactions in solution and in a Chol-rich membrane environment. LLO has six tryptophan residues located in the region of the molecule that is first in contact with lipid membranes. 19F-LLO, which contained 5-fluoro-tryptophans, was prepared by using isotopic labelling in an E. coli expression system. Signals in the 19F-NMR spectrum of 19F-LLO were unambiguously assigned by using a series of single Trp → Phe point mutations. The results employing various cholesterol preparations in solution indicate that tryptophan residues are not directly involved in Chol binding in solution. However, significant chemical shift changes were observed upon LLO binding to Chol-rich membranes, highlighting the role of tryptophan residues in membrane interactions (W512) and oligomerisation (W189 and W489).
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Affiliation(s)
- Mirijam Kozorog
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia.,Graduate School of Biomedicine, Medical faculty, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | | | - Gregor Ilc
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Vesna Hodnik
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia.,EN-FIST Centre of Excellence, Trg Osvobodilne fronte 13, 1001, Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000, Ljubljana, Slovenia
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia.
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6
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Protein arcs may form stable pores in lipid membranes. Biophys J 2014; 106:154-61. [PMID: 24411247 DOI: 10.1016/j.bpj.2013.11.4490] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 11/04/2013] [Accepted: 11/22/2013] [Indexed: 01/22/2023] Open
Abstract
Electron microscopy and atomic force microscopy images of cholesterol-dependent cytolysins and related proteins that form large pores in lipid membranes have revealed the presence of incomplete rings, or arcs. Some evidence indicates that these arcs are inserted into the membrane and induce membrane leakage, but other experiments seem to refute that. Could such pores, only partially lined by protein, be kinetically and thermodynamically stable? How would the lipids be structured in such a pore? Using the antimicrobial peptide protegrin-1 as a model, we test the stability of pores only partially lined by peptide using all-atom molecular dynamics simulations in POPC and POPE/POPG membranes. The data show that, whereas pure lipid pores close rapidly, pores partially lined by protegrin arcs are stable for at least 300 ns. Estimates of the thermodynamic stability of these arcs using line tension data and implicit solvent calculations show that these arcs can be marginally stable in both zwitterionic and anionic membranes. Arcs provide an explanation for the observed ion selectivity in protegrin electrophysiology experiments and could possibly be involved in other membrane permeabilization processes where lipids are thought to participate, such as those induced by antimicrobial peptides and colicins, as well as the Bax apoptotic pore.
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7
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Hotze EM, Tweten RK. Membrane assembly of the cholesterol-dependent cytolysin pore complex. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1818:1028-38. [PMID: 21835159 PMCID: PMC3243806 DOI: 10.1016/j.bbamem.2011.07.036] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 07/24/2011] [Indexed: 12/16/2022]
Abstract
The cholesterol-dependent cytolysins (CDCs) are a large family of pore-forming toxins that are produced, secreted and contribute to the pathogenesis of many species of Gram-positive bacteria. The assembly of the CDC pore-forming complex has been under intense study for the past 20 years. These studies have revealed a molecular mechanism of pore formation that exhibits many novel features. The CDCs form large β-barrel pore complexes that are assembled from 35 to 40 soluble CDC monomers. Pore formation is dependent on the presence of membrane cholesterol, which functions as the receptor for most CDCs. Cholesterol binding initiates significant secondary and tertiary structural changes in the monomers, which lead to the assembly of a large membrane embedded β-barrel pore complex. This review will focus on the molecular mechanism of assembly of the CDC membrane pore complex and how these studies have led to insights into the mechanism of pore formation for other pore-forming proteins. This article is part of a Special Issue entitled: Protein Folding in Membranes.
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Affiliation(s)
- Eileen M. Hotze
- Department of Microbiology and Immunology, The University of Oklahoma Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Rodney K. Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Sciences Center, Oklahoma City, Oklahoma 73104, USA
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8
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Montero J, Morales A, Llacuna L, Lluis JM, Terrones O, Basañez G, Antonsson B, Prieto J, García-Ruiz C, Colell A, Fernández-Checa JC. Mitochondrial Cholesterol Contributes to Chemotherapy Resistance in Hepatocellular Carcinoma. Cancer Res 2008; 68:5246-56. [DOI: 10.1158/0008-5472.can-07-6161] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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9
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Structural elements of the cholesterol-dependent cytolysins that are responsible for their cholesterol-sensitive membrane interactions. Proc Natl Acad Sci U S A 2007; 104:20226-31. [PMID: 18077338 DOI: 10.1073/pnas.0708104105] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The pore-forming mechanism of the cholesterol-dependent cytolysins (CDCs) exhibits an absolute requirement for membrane cholesterol. The structural elements of the CDCs that mediate this interaction are not well understood. Three short hydrophobic loops (L1-L3) and a highly conserved undecapeptide sequence at the tip of domain 4 of the CDC structure are known to anchor the CDC to the membrane. It has been thought that the undecapeptide directly mediates the interaction of the CDCs with a cholesterol-rich cell surface. Herein we show that the L1-L3 loops, not the undecapeptide, are responsible for mediating the specific interaction of the CDCs with cholesterol-rich membranes. The membrane insertion of the undecapeptide was uncoupled from membrane binding by the covalent modification of the undecapeptide cysteine thiol. Modification of the cysteine prevented prepore to pore conversion, but did not affect membrane binding, thus demonstrating that undecapeptide membrane insertion follows that of the L1-L3 loops. These studies provide an example of a structural motif that specifically mediates the interaction of a bacterial toxin with a cholesterol-rich membrane.
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Madan V, Sánchez-Martínez S, Vedovato N, Rispoli G, Carrasco L, Nieva JL. Plasma membrane-porating domain in poliovirus 2B protein. A short peptide mimics viroporin activity. J Mol Biol 2007; 374:951-64. [PMID: 17963782 DOI: 10.1016/j.jmb.2007.09.058] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 09/13/2007] [Accepted: 09/20/2007] [Indexed: 11/30/2022]
Abstract
Picornavirus 2B, a non-structural protein required for effective viral replication, has been implicated in cell membrane permeabilization during the late phases of infection. Here, we have approached the molecular mechanism of this process by assessing the pore-forming activity of an overlapping peptide library that spanned the complete 2B sequence. At non-cytopathic concentrations, only the P3 peptide, spanning 2B residues 35-55, effectively assembled hydrophilic pores that allowed diffusion of low molecular mass solutes across the cell plasma membrane (IC(50) approximately 4x10(-7) M) and boundary liposome bilayers (starting at peptide to lipid molar ratios>1:10(4)). Circular dichroism data were consistent with its capacity to fold as a helix in a membrane-like environment. Furthermore, addition of this peptide to a sealed plasma-membrane model, consisting of retinal rod outer segments patch-clamped in a whole-cell configuration, induced ion channel activity within seconds at concentrations as low as 10(-8) M. Thus, we have established a "one-helix" 2B version that possesses the intrinsic pore-forming activity required to directly and effectively permeabilize the cell plasma membrane. We conclude that 2B viroporin can be classified as a genuine pore-forming toxin of viral origin, which is produced intracellularly at certain times post infection.
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Affiliation(s)
- Vanesa Madan
- Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain
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11
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Bhakdi S, Tranum-Jensen J. Damage to mammalian cells by proteins that form transmembrane pores. Rev Physiol Biochem Pharmacol 2005; 107:147-223. [PMID: 3303271 DOI: 10.1007/bfb0027646] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Affiliation(s)
- Rodney K Tweten
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, 73104, USA.
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13
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Abstract
In view of the recent studies on the CDCs, a reasonable schematic of the stages leading to membrane insertion of the CDCs can be assembled. As shown in Fig. 3, we propose that the CDC first binds to the membrane as a monomer. These monomers then diffuse laterally on the membrane surface to encounter other monomers or incomplete oligomeric complexes. Presumably, once the requisite oligomer size is reached, the prepore complex is converted into the pore complex and a large membrane channel is formed. During the conversion of the prepore complex to the pore complex, we predict that the TMHs of the subunits in the prepore complex insert into the bilayer in a concerted fashion to form the large transmembrane beta-barrel, although this still remains to be confirmed experimentally. Many intriguing problems concerning the cytolytic mechanism of the CDCs remain unsolved. The nature of the initial interaction of the CDC monomer with the membrane is currently one of the most controversial questions concerning the CDC mechanism. Is cholesterol involved in this interaction, as previously assumed, or do specific receptors exist for these toxins that remain to be discovered? Also, the trigger for membrane insertion and the regions of these toxins that facilitate the [figure: see text] interaction of the monomers during prepore complex formation are unknown. In addition, the temporal sequence of the multiple structural changes that accompany the conversion of the soluble CDC monomer into a membrane-inserted oligomer have yet to be defined or characterized kinetically.
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Affiliation(s)
- R K Tweten
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA
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Palmer M, Vulicevic I, Saweljew P, Valeva A, Kehoe M, Bhakdi S. Streptolysin O: a proposed model of allosteric interaction between a pore-forming protein and its target lipid bilayer. Biochemistry 1998; 37:2378-83. [PMID: 9485385 DOI: 10.1021/bi9720890] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Streptolysin O, a polypeptide of 571 amino acids, belongs to the family of thiol-activated toxins that permeabilize animal cell membranes. The protein binds as a monomer to membrane cholesterol. Binding involves a conserved region close to the C-terminus and triggers subsequent polymerization into large arc- and ring-shaped structures surrounding pores of up to 30 nm. Besides the C-terminus, a distantly located region spanning residues 213-305 is involved in oligomerization and in membrane insertion. Here, we searched for conformational effects of monomer binding to the latter functionally important region. To this end, single cysteine substitution mutants were produced and derivatized with the polarity-sensitive fluorophore acrylodan. Fluorimetric measurements revealed that binding of the monomer to membranes is accompanied by distinct environmental changes at amino acid residues 218, 248, 266, and 277. Conspicuously, the environment of residues 218 and 266 became more hydrophilic, suggesting movement of these residues out of hydrophobic protein pockets. Upon oligomerization, further alterations in all side-chain environments were observed. The membrane-bound monomer thus differs in conformation from both the monomer in solution and the subunit of the oligomer. The putative binding site of the molecule is linked to remote domains involved in oligomerization and membrane insertion in an apparently allosteric fashion. It is proposed that allostery is responsible for restricting oligomerization to the membrane-bound state of the toxin.
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Affiliation(s)
- M Palmer
- Institute of Medical Microbiology, University of Mainz, Augustusplatz, D55101 Germany
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15
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Rossjohn J, Feil SC, McKinstry WJ, Tweten RK, Parker MW. Structure of a cholesterol-binding, thiol-activated cytolysin and a model of its membrane form. Cell 1997; 89:685-92. [PMID: 9182756 DOI: 10.1016/s0092-8674(00)80251-2] [Citation(s) in RCA: 352] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The mechanisms by which proteins gain entry into membranes is a fundamental problem in biology. Here, we present the first crystal structure of a thiol-activated cytolysin, perfringolysin O, a member of a large family of toxins that kill eukaryotic cells by punching holes in their membranes. The molecule adopts an unusually elongated shape rich in beta sheet. We have used electron microscopy data to construct a detailed model of the membrane channel form of the toxin. The structures reveal a novel mechanism for membrane insertion. Surprisingly, the toxin receptor, cholesterol, appears to play multiple roles: targeting, promotion of oligomerization, triggering a membrane insertion competent form, and stabilizing the membrane pore.
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Affiliation(s)
- J Rossjohn
- The Ian Potter Foundation Protein Crystallography Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
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16
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Bonvini E, Debell KE, Taplits MS, Brando C, Laurenza A, Seamon K, Hoffman T. A role for guanine-nucleotide-binding proteins in mediating T-cell-receptor coupling to inositol phospholipid hydrolysis in a murine T-helper (type II) lymphocyte clone. Biochem J 1991; 275 ( Pt 3):689-96. [PMID: 1645519 PMCID: PMC1150204 DOI: 10.1042/bj2750689] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Perturbation of the T-cell receptor (TCR) complex is followed by the rapid hydrolysis of inositol phospholipids (InsPL) by phospholipase C (PLC), producing diacylglycerol and inositol phosphates, which act as second messengers in signal transduction. The mechanism coupling the TCR to InsPL hydrolysis is not clearly defined, and no information is available on this mechanism in the CD4+ helper subset of T-lymphocytes (Th). We have tested the hypothesis that guanine-nucleotide-binding proteins (G-proteins) may couple the TCR to PLC in a murine Th type II (Th2) cell clone. Cell permeabilization with streptolysin O (SLO) or tetanolysin (TL) was used to allow membrane-impermeable nucleotides access to intracellular sites of action. Exposure of permeabilized Th2 cells to guanosine 5'-[gamma-thio]triphosphate (GTP gamma S), a non-hydrolysable GTP analogue, resulted in a 2.1-2.5-fold increase in inositol phosphate generation. Similarly, perturbation of the TCR with the monoclonal antibody 145.2C11 (directed against the epsilon-chain of the CD3 component of the TCR) resulted in a 3.1-4.2-fold increase in InsPL hydrolysis by permeabilized cells. Both lysins were similarly effective in allowing GTP gamma S induction of InsPL hydrolysis, but TL-permeabilized cells responded better to TCR perturbation than SLO-treated cells. A role for G-proteins in TCR coupling to PLC was further supported by the inhibition of TCR-induced InsPL hydrolysis by guanosine 5'-[beta-thio]diphosphate (GDP beta S), a guanine nucleotide analogue that inhibits G-protein function. ATP was required for TCR-mediated InsPL hydrolysis, and potentiated GTP gamma S-induced hydrolysis. Other nucleotides (i.e. CTP, GDP, GTP, ITP) did not affect the response. These data indicate that G-proteins may contribute to the regulation of PLC activation in Th2 cells, coupling it to the TCR.
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Affiliation(s)
- E Bonvini
- Laboratory of Cell Biology, U.S. Food and Drug Administration, Bethesda, MD 20892
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18
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Yamanaka H, Katsu T, Satoh T, Shimatani S, Shinoda S. Effect ofVibrio vulnificushemolysin on liposome membranes. FEMS Microbiol Lett 1987. [DOI: 10.1111/j.1574-6968.1987.tb02278.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Abstract
Streptolysin-O (SLO) is a thiol-activated, membrane-damaging protein toxin of Mr 69,000 that is produced by most strains of beta-hemolytic group A streptococci. Native, primarily water-soluble toxin molecules bind to cholesterol-containing target membranes to assemble into supramolecular curved rod structures (25 to 100 nm long by ca. 7.5 nm wide), forming rings and arcs that penetrate into the apolar domain of the bilayer. Electron microscopic analyses of toxin polymers in their native and reconstituted membrane-bound form indicate that the convex surface of the rod structures is a hydrophobic, lipid-binding domain, whereas the concave surfaces appear to be hydrophilic. The embedment of the rings and arcs generates large transmembrane slits or pores of up to 30-nm diameter that can be directly visualized by negative staining and freeze-fracture electron microscopy. SLO oligomers were isolated in extensively delipidated form in detergent solution, and cholesterol was found not to detectably contribute to the observed rod structures. The rods are stable structures that resist prolonged exposure to trypsin and chymotrypsin. They can be reincorporated into cholesterol-free phosphatidylcholine liposomes to generate lesions identical to those observed on erythrocytes lysed by native SLO. Thus, although cholesterol plays a key role in the initial binding of SLO to the membrane, it does not directly participate in the formation of the membrane-penetrating toxin channels. Membrane damage by SLO is basically analogous to that mediated by previously studied channel formers, namely, the C5b-9 complement complex and staphylococcal alpha-toxin.
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Bhakdi S, Tranum-Jensen J. Formation of protein channels in target membranes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1985; 184:3-21. [PMID: 3898753 DOI: 10.1007/978-1-4684-8326-0_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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