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Lv P, Yang Y, Li S, Tan CS, Ming D. Biological nanopore approach for single‐molecule analysis of nucleobase modifications. ELECTROCHEMICAL SCIENCE ADVANCES 2021. [DOI: 10.1002/elsa.202100119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Pengrui Lv
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Yongyi Yang
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Shuang Li
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Cherie S. Tan
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
| | - Dong Ming
- Academy of Medical Engineering and Translational Medicine Tianjin University Tianjin China
- Department of Biomedical Engineering College of Precision Instruments and Optoelectronics Engineering Tianjin University Tianjin China
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2
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Tan CS, Fleming AM, Ren H, Burrows CJ, White HS. γ-Hemolysin Nanopore Is Sensitive to Guanine-to-Inosine Substitutions in Double-Stranded DNA at the Single-Molecule Level. J Am Chem Soc 2018; 140:14224-14234. [PMID: 30269492 DOI: 10.1021/jacs.8b08153] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Biological nanopores provide a unique single-molecule sensing platform to detect target molecules based on their specific electrical signatures. The γ-hemolysin (γ-HL) protein produced by Staphylococcus aureus is able to assemble into an octamer nanopore with a ∼2.3 nm diameter β-barrel. Herein, we demonstrate the first application of γ-HL nanopore for DNA structural analysis. To optimize conditions for ion-channel recording, the properties of the γ-HL pore (e.g., conductance, voltage-dependent gating, and ion-selectivity) were characterized at different pH, temperature, and electrolyte concentrations. The optimal condition for DNA analysis using γ-HL corresponds to 3 M KCl, pH 5, and T = 20 °C. The γ-HL protein nanopore is able to translocate dsDNA at about ∼20 bp/ms, and the unique current-signature of captured dsDNA can directly distinguish guanine-to-inosine substitutions at the single-molecule level with ∼99% accuracy. The slow dsDNA threading and translocation processes indicate this wild-type γ-HL channel has potential to detect other base modifications in dsDNA.
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Affiliation(s)
- Cherie S Tan
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Aaron M Fleming
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Hang Ren
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Cynthia J Burrows
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
| | - Henry S White
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 , United States
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3
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The bicomponent pore-forming leucocidins of Staphylococcus aureus. Microbiol Mol Biol Rev 2015; 78:199-230. [PMID: 24847020 DOI: 10.1128/mmbr.00055-13] [Citation(s) in RCA: 192] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The ability to produce water-soluble proteins with the capacity to oligomerize and form pores within cellular lipid bilayers is a trait conserved among nearly all forms of life, including humans, single-celled eukaryotes, and numerous bacterial species. In bacteria, some of the most notable pore-forming molecules are protein toxins that interact with mammalian cell membranes to promote lysis, deliver effectors, and modulate cellular homeostasis. Of the bacterial species capable of producing pore-forming toxic molecules, the Gram-positive pathogen Staphylococcus aureus is one of the most notorious. S. aureus can produce seven different pore-forming protein toxins, all of which are believed to play a unique role in promoting the ability of the organism to cause disease in humans and other mammals. The most diverse of these pore-forming toxins, in terms of both functional activity and global representation within S. aureus clinical isolates, are the bicomponent leucocidins. From the first description of their activity on host immune cells over 100 years ago to the detailed investigations of their biochemical function today, the leucocidins remain at the forefront of S. aureus pathogenesis research initiatives. Study of their mode of action is of immediate interest in the realm of therapeutic agent design as well as for studies of bacterial pathogenesis. This review provides an updated perspective on our understanding of the S. aureus leucocidins and their function, specificity, and potential as therapeutic targets.
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Tawk MY, Zimmermann K, Bossu J, Potrich C, Bourcier T, Dalla Serra M, Poulain B, Prévost G, Jover E. Internalization of staphylococcal leukotoxins that bind and divert the
C
5a receptor is required for intracellular
Ca
2+
mobilization by human neutrophils. Cell Microbiol 2015; 17:1241-57. [DOI: 10.1111/cmi.12434] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/26/2015] [Accepted: 03/01/2015] [Indexed: 01/12/2023]
Affiliation(s)
- Mira Y. Tawk
- Fédération de Médecine Translationnelle de Strasbourg EA7290 Virulence Bactérienne Précoce Institut de Bactériologie et Hôpitaux Universitaires de Strasbourg Université de Strasbourg Strasbourg France
| | - Kiran Zimmermann
- Fédération de Médecine Translationnelle de Strasbourg EA7290 Virulence Bactérienne Précoce Institut de Bactériologie et Hôpitaux Universitaires de Strasbourg Université de Strasbourg Strasbourg France
| | - Jean‐Louis Bossu
- INCI – UPR‐CNRS 3212 Physiologie des réseaux de neurones Strasbourg France
| | - Cristina Potrich
- National Research Council of Italy Institute of Biophysics and Bruno Kessler Foundation Trento Italy
| | - Tristan Bourcier
- Fédération de Médecine Translationnelle de Strasbourg EA7290 Virulence Bactérienne Précoce Institut de Bactériologie et Hôpitaux Universitaires de Strasbourg Université de Strasbourg Strasbourg France
| | - Mauro Dalla Serra
- National Research Council of Italy Institute of Biophysics and Bruno Kessler Foundation Trento Italy
| | - Bernard Poulain
- INCI – UPR‐CNRS 3212 Physiologie des réseaux de neurones Strasbourg France
| | - Gilles Prévost
- Fédération de Médecine Translationnelle de Strasbourg EA7290 Virulence Bactérienne Précoce Institut de Bactériologie et Hôpitaux Universitaires de Strasbourg Université de Strasbourg Strasbourg France
| | - Emmanuel Jover
- Fédération de Médecine Translationnelle de Strasbourg EA7290 Virulence Bactérienne Précoce Institut de Bactériologie et Hôpitaux Universitaires de Strasbourg Université de Strasbourg Strasbourg France
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Abstract
The cell membrane is crucial for protection of the cell from its environment. MACPF/CDC proteins are a large superfamily known to be essential for bacterial pathogenesis and proper functioning of the immune system. The three most studied groups of MACPF/CDC proteins are cholesterol-dependent cytolysins from bacteria, the membrane attack complex of complement and human perforin. Their primary function is to form transmembrane pores in target cell membranes. The common mechanism of action comprises water-soluble monomeric proteins binding to the host cell membrane, oligomerization, and formation of a functional pore. This causes a disturbance in gradients of ions and other molecules across the membrane and can lead to cell death. Cells react to this form of attack in a complex manner. Responses can be general, like removing the perforated part of the membrane, or more specific, in many cases depending on binding of proteins to specific receptors to trigger various signalling cascades.
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Rojko N, Kristan KČ, Viero G, Žerovnik E, Maček P, Dalla Serra M, Anderluh G. Membrane damage by an α-helical pore-forming protein, Equinatoxin II, proceeds through a succession of ordered steps. J Biol Chem 2013; 288:23704-15. [PMID: 23803608 DOI: 10.1074/jbc.m113.481572] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Actinoporin equinatoxin II (EqtII) is an archetypal example of α-helical pore-forming toxins that porate cellular membranes by the use of α-helices. Previous studies proposed several steps in the pore formation: binding of monomeric protein onto the membrane, followed by oligomerization and insertion of the N-terminal α-helix into the lipid bilayer. We studied these separate steps with an EqtII triple cysteine mutant. The mutant was engineered to monitor the insertion of the N terminus into the lipid bilayer by labeling Cys-18 with a fluorescence probe and at the same time to control the flexibility of the N-terminal region by the disulfide bond formed between cysteines introduced at positions 8 and 69. The insertion of the N terminus into the membrane proceeded shortly after the toxin binding and was followed by oligomerization. The oxidized, non-lytic, form of the mutant was still able to bind to membranes and oligomerize at the same level as the wild-type or the reduced form. However, the kinetics of the N-terminal helix insertion, the release of calcein from erythrocyte ghosts, and hemolysis of erythrocytes was much slower when membrane-bound oxidized mutant was reduced by the addition of the reductant. Results show that the N-terminal region needs to be inserted in the lipid membrane before the oligomerization into the final pore and imply that there is no need for a stable prepore formation. This is different from β-pore-forming toxins that often form β-barrel pores via a stable prepore complex.
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Affiliation(s)
- Nejc Rojko
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
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7
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Gilbert RJC, Mikelj M, Dalla Serra M, Froelich CJ, Anderluh G. Effects of MACPF/CDC proteins on lipid membranes. Cell Mol Life Sci 2013; 70:2083-98. [PMID: 22983385 PMCID: PMC11114033 DOI: 10.1007/s00018-012-1153-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/29/2012] [Accepted: 08/30/2012] [Indexed: 12/15/2022]
Abstract
Recent work on the MACPF/CDC superfamily of pore-forming proteins has focused on the structural analysis of monomers and pore-forming oligomeric complexes. We set the family of proteins in context and highlight aspects of their function which the direct and exclusive equation of oligomers with pores fails to explain. Starting with a description of the distribution of MACPF/CDC proteins across the domains of life, we proceed to show how their evolutionary relationships can be understood on the basis of their structural homology and re-evaluate models for pore formation by perforin, in particular. We furthermore highlight data showing the role of incomplete oligomeric rings (arcs) in pore formation and how this can explain small pores generated by oligomers of proteins belonging to the family. We set this in the context of cell biological and biophysical data on the proteins' function and discuss how this helps in the development of an understanding of how they act in processes such as apicomplexan parasites gliding through cells and exiting from cells.
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Affiliation(s)
- Robert J. C. Gilbert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN UK
| | - Miha Mikelj
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Mauro Dalla Serra
- National Research Council, Institute of Biophysics and Bruno Kessler Foundation, via alla Cascata 56/C, 38123 Trento, Italy
| | - Christopher J. Froelich
- Department of Medicine, NorthShore University HealthSystem Research Institute, Evanston, IL 60201 USA
| | - Gregor Anderluh
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
- National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
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8
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p-Sulfonato-calix[n]arenes inhibit staphylococcal bicomponent leukotoxins by supramolecular interactions. Biochem J 2013; 450:559-71. [PMID: 23282185 DOI: 10.1042/bj20121628] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PVL (Panton-Valentine leukocidin) and other Staphylococcus aureus β-stranded pore-forming toxins are important virulence factors involved in various pathologies that are often necrotizing. The present study characterized leukotoxin inhibition by selected SCns (p-sulfonato-calix[n]arenes): SC4, SC6 and SC8. These chemicals have no toxic effects on human erythrocytes or neutrophils, and some are able to inhibit both the activity of and the cell lysis by leukotoxins in a dose-dependent manner. Depending on the type of leukotoxins and SCns, flow cytometry revealed IC50 values of 6-22 μM for Ca2+ activation and of 2-50 μM for cell lysis. SCns were observed to affect membrane binding of class S proteins responsible for cell specificity. Electrospray MS and surface plasmon resonance established supramolecular interactions (1:1 stoichiometry) between SCns and class S proteins in solution, but not class F proteins. The membrane-binding affinity of S proteins was Kd=0.07-6.2 nM. The binding ability was completely abolished by SCns at different concentrations according to the number of benzenes (30-300 μM; SC8>SC6≫SC4). The inhibitory properties of SCns were also observed in vivo in a rabbit model of PVL-induced endophthalmitis. These calixarenes may represent new therapeutic avenues aimed at minimizing inflammatory reactions and necrosis due to certain virulence factors.
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Savva CG, Fernandes da Costa SP, Bokori-Brown M, Naylor CE, Cole AR, Moss DS, Titball RW, Basak AK. Molecular architecture and functional analysis of NetB, a pore-forming toxin from Clostridium perfringens. J Biol Chem 2012; 288:3512-22. [PMID: 23239883 PMCID: PMC3561570 DOI: 10.1074/jbc.m112.430223] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
NetB is a pore-forming toxin produced by Clostridium perfringens and has been reported to play a major role in the pathogenesis of avian necrotic enteritis, a disease that has emerged due to the removal of antibiotics in animal feedstuffs. Here we present the crystal structure of the pore form of NetB solved to 3.9 Å. The heptameric assembly shares structural homology to the staphylococcal α-hemolysin. However, the rim domain, a region that is thought to interact with the target cell membrane, shows sequence and structural divergence leading to the alteration of a phosphocholine binding pocket found in the staphylococcal toxins. Consistent with the structure we show that NetB does not bind phosphocholine efficiently but instead interacts directly with cholesterol leading to enhanced oligomerization and pore formation. Finally we have identified conserved and non-conserved amino acid positions within the rim loops that significantly affect binding and toxicity of NetB. These findings present new insights into the mode of action of these pore-forming toxins, enabling the design of more effective control measures against necrotic enteritis and providing potential new tools to the field of bionanotechnology.
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Affiliation(s)
- Christos G Savva
- Department of Biological Sciences, School of Crystallography, Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London, WC1E 7HX, United Kingdom
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10
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Alessandrini A, Viero G, Dalla Serra M, Prévost G, Facci P. γ-Hemolysin oligomeric structure and effect of its formation on supported lipid bilayers: an AFM investigation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:405-11. [PMID: 23036932 DOI: 10.1016/j.bbamem.2012.09.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 09/05/2012] [Accepted: 09/25/2012] [Indexed: 11/28/2022]
Abstract
γ-Hemolysins are bicomponent β-barrel pore forming toxins produced by Staphylococcus aureus as water-soluble monomers, which assemble into oligomeric pores on the surface of lipid bilayers. Here, after investigating the oligomeric structure of γ-hemolysins on supported lipid bilayers (SLBs) by atomic force microscopy (AFM), we studied the effect produced by this toxin on the structure of SLBs. We found that oligomeric structures with different number of monomers can assemble on the lipid bilayer being the octameric form the stablest one. Moreover, in this membrane model we found that γ-hemolysins can form clusters of oligomers inducing a curvature in the lipid bilayer, which could probably enhance the aggressiveness of these toxins at high concentrations.
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Affiliation(s)
- Andrea Alessandrini
- Centro S3, CNR-Istituto di Nanoscienze, Via Campi 213/A, 41125 Modena, Italy.
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11
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Bonardi F, Nouwen N, Feringa BL, Driessen AJM. Protein conducting channels—mechanisms, structures and applications. MOLECULAR BIOSYSTEMS 2012; 8:709-19. [DOI: 10.1039/c2mb05433g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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12
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Crystal structure of the octameric pore of staphylococcal γ-hemolysin reveals the β-barrel pore formation mechanism by two components. Proc Natl Acad Sci U S A 2011; 108:17314-9. [PMID: 21969538 DOI: 10.1073/pnas.1110402108] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcal γ-hemolysin is a bicomponent pore-forming toxin composed of LukF and Hlg2. These proteins are expressed as water-soluble monomers and then assemble into the oligomeric pore form on the target cell. Here, we report the crystal structure of the octameric pore form of γ-hemolysin at 2.5 Å resolution, which is the first high-resolution structure of a β-barrel transmembrane protein composed of two proteins reported to date. The octameric assembly consists of four molecules of LukF and Hlg2 located alternately in a circular pattern, which explains the biochemical data accumulated over the past two decades. The structure, in combination with the monomeric forms, demonstrates the elaborate molecular machinery involved in pore formation by two different molecules, in which interprotomer electrostatic interactions using loops connecting β2 and β3 (loop A: Asp43-Lys48 of LukF and Lys37-Lys43 of Hlg2) play pivotal roles as the structural determinants for assembly through unwinding of the N-terminal β-strands (amino-latch) of the adjacent protomer, releasing the transmembrane stem domain folded into a β-sheet in the monomer (prestem), and interaction with the adjacent protomer.
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13
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Heavy chain-only antibodies and tetravalent bispecific antibody neutralizing Staphylococcus aureus leukotoxins. Proc Natl Acad Sci U S A 2011; 108:16404-9. [PMID: 21930905 DOI: 10.1073/pnas.1102265108] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Panton-Valentine leukocidin (PVL) is a pore-forming toxin associated with current outbreaks of community-associated methicillin-resistant strains and implicated directly in the pathophysiology of Staphylococcus aureus-related diseases. Humanized heavy chain-only antibodies (HCAb) were generated against S. aureus PVL from immunized transgenic mice to neutralize toxin activity. The active form of PVL consists of the two components, LukS-PV and LukF-PV, which induce osmotic lysis following pore formation in host defense cells. One anti-LukS-PV HCAb, three anti-LukF-PV HCAbs with affinities in the nanomolar range, and one engineered tetravalent bispecific HCAb were tested in vitro and in vivo, and all prevented toxin binding and pore formation. Anti-LukS-PV HCAb also binds to γ-hemolysin C (HlgC) and inhibits HlgC/HlgB pore formation. Experiments in vivo in a toxin-induced rabbit endophthalmitis model showed that these HCAbs inhibit inflammatory reactions and tissue destruction, with the tetravalent bispecific HCAb performing best. Our findings show the therapeutic potential of HCAbs, and in particular, bispecific antibodies.
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Fromageau A, Gilbert FB, Prévost G, Rainard P. Binding of the Staphylococcus aureus leucotoxin LukM to its leucocyte targets. Microb Pathog 2010; 49:354-62. [PMID: 20624452 DOI: 10.1016/j.micpath.2010.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 06/24/2010] [Accepted: 07/03/2010] [Indexed: 10/19/2022]
Abstract
The range of leucocytes susceptible to the leucotoxin LukM/F', a two-component pore-forming toxin of Staphylococcus aureus causing mastitis in ruminants, had not been defined. We used fluorescent-labeled LukM to investigate the binding of this toxin to bovine cells and to identify its cellular targets among bovine, human and murine leucocytes. LukM bound to bovine blood neutrophils from all the individuals tested with similar affinity, with an apparent dissociation constant (Kd) of 1.81 ± 0.14 nM and 13 3100 ± 506 binding sites. The amount of LukM bound to bovine neutrophils did not depend on the presence of the complementary component LukF', suggesting that the binding of LukM to its ligand does not depend on the formation of pore-forming oligomers, and that the number of bound LukM molecules corresponds to the number of available cell membrane ligands. Other staphylococcal class S components of bipartite leucotoxins (HlgA, HlgC, LukE, LukS-PV) were inefficient competitors of LukM for the binding to bovine neutrophils, indicating that LukM has a distinct ligand on target cells. Bovine blood neutrophils bound slightly more LukM than did milk neutrophils, and much more than did ovine and caprine blood neutrophils. Bovine monocytes and milk macrophages readily bound LukM, whereas blood lymphocytes did not. Human neutrophils bound little LukM and were resistant to LukM/F' at the highest tested concentration (40 nM). Murine neutrophils bound LukM and were susceptible to the toxicity of LukM/F', exhibiting flattening and nucleus alteration beginning at 0.3 nM concentration. Among murine peritoneal exudate cells, T lymphocytes (CD3+) and monocytes/macrophages (F4/80+) bound LukM, whereas binding to B lymphocytes (CD19+) was not detected. These results indicate that cells of the myeloid lineage are the main targets of LukM/F' in dairy ruminants, and that resident or inflammatory migrated phagocytes are susceptible to this toxin.
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Affiliation(s)
- Angélina Fromageau
- INRA, UR1282 Infectiologie Animale et Santé Publique (IASP), Bâtiment 311, F-37380 Nouzilly, France
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15
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Joubert O, Voegelin J, Guillet V, Tranier S, Werner S, Colin DA, Serra MD, Keller D, Monteil H, Mourey L, Prévost G. Distinction between pore assembly by staphylococcal alpha-toxin versus leukotoxins. J Biomed Biotechnol 2007; 2007:25935. [PMID: 17497023 PMCID: PMC1847480 DOI: 10.1155/2007/25935] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 11/07/2006] [Accepted: 12/06/2006] [Indexed: 11/23/2022] Open
Abstract
The staphylococcal bipartite leukotoxins and the homoheptameric α-toxin belong to the same family of β-barrel pore-forming toxins despite slight differences. In the α-toxin pore, the N-terminal extremity of each protomer interacts as a deployed latch with two consecutive protomers in the vicinity of the pore lumen. N-terminal extremities of leukotoxins as seen in their three-dimensional structures are heterogeneous in length and take part in the β-sandwich core of soluble monomers. Hence, the interaction of these N-terminal extremities within structures of adjacent monomers is questionable. We show here that modifications of their N-termini by two different processes, using fusion with glutathione S-transferase (GST) and bridging of the N-terminal extremity to the adjacent β-sheet via disulphide bridges, are not deleterious for biological activity. Therefore, bipartite leukotoxins do not need a large extension of their N-terminal extremities to form functional pores, thus illustrating a microheterogeneity of the structural organizations between bipartite leukotoxins and α-toxin.
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Affiliation(s)
- Olivier Joubert
- Laboratoire de Physiopathologie et d'Antibiologie des Infections Bactériennes Emergentes et Nosocomiales, EA 3432,
Institut de Bactériologie de la Faculté de Médecine, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg,
3 Rue Koeberlé, 67000 Strasbourg, France
| | - Joëlle Voegelin
- Laboratoire de Physiopathologie et d'Antibiologie des Infections Bactériennes Emergentes et Nosocomiales, EA 3432,
Institut de Bactériologie de la Faculté de Médecine, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg,
3 Rue Koeberlé, 67000 Strasbourg, France
| | - Valérie Guillet
- Groupe de Biophysique Structurale, Département Mécanismes Moléculaires des Infections Mycobactériennes,
Institut de Pharmacologie et de Biologie Structurale (IPBS), CNRS-UMR 5089, 205 Route de Narbonne, 31077 Toulouse Cedex, France
| | - Samuel Tranier
- Groupe de Biophysique Structurale, Département Mécanismes Moléculaires des Infections Mycobactériennes,
Institut de Pharmacologie et de Biologie Structurale (IPBS), CNRS-UMR 5089, 205 Route de Narbonne, 31077 Toulouse Cedex, France
| | - Sandra Werner
- Société Parogène, Faculté de Médecine et d'Odontologie, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg,
11 Rue Humann, 67085 Strasbourg Cedex, France
| | - Didier A. Colin
- Laboratoire de Physiopathologie et d'Antibiologie des Infections Bactériennes Emergentes et Nosocomiales, EA 3432,
Institut de Bactériologie de la Faculté de Médecine, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg,
3 Rue Koeberlé, 67000 Strasbourg, France
| | - Mauro Dalla Serra
- Istituto di BioFisica (IBF), Consiglio Nazionale delle Richerche (CNR), Via Sommarive 18, 38050 Povo, Trento, Italy
| | - Daniel Keller
- Laboratoire de Physiopathologie et d'Antibiologie des Infections Bactériennes Emergentes et Nosocomiales, EA 3432,
Institut de Bactériologie de la Faculté de Médecine, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg,
3 Rue Koeberlé, 67000 Strasbourg, France
| | - Henri Monteil
- Laboratoire de Physiopathologie et d'Antibiologie des Infections Bactériennes Emergentes et Nosocomiales, EA 3432,
Institut de Bactériologie de la Faculté de Médecine, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg,
3 Rue Koeberlé, 67000 Strasbourg, France
| | - Lionel Mourey
- Groupe de Biophysique Structurale, Département Mécanismes Moléculaires des Infections Mycobactériennes,
Institut de Pharmacologie et de Biologie Structurale (IPBS), CNRS-UMR 5089, 205 Route de Narbonne, 31077 Toulouse Cedex, France
| | - Gilles Prévost
- Laboratoire de Physiopathologie et d'Antibiologie des Infections Bactériennes Emergentes et Nosocomiales, EA 3432,
Institut de Bactériologie de la Faculté de Médecine, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg,
3 Rue Koeberlé, 67000 Strasbourg, France
- *Gilles Prévost:
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16
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Kristan K, Viero G, Macek P, Dalla Serra M, Anderluh G. The equinatoxin N-terminus is transferred across planar lipid membranes and helps to stabilize the transmembrane pore. FEBS J 2006; 274:539-50. [PMID: 17229155 DOI: 10.1111/j.1742-4658.2006.05608.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Equinatoxin II is a cytolytic protein isolated from the sea anemone Actinia equina. It is a member of the actinoporins, a family of eukaryotic pore-forming toxins with a unique mechanism of pore formation. Equinatoxin II is a 20 kDa cysteineless protein, with sphingomyelin-dependent activity. Recent studies showed that the N-terminal region of the molecule requires conformational flexibility during pore formation. An understanding of the N-terminal position in the final pore and its role in membrane insertion and pore stability is essential to define the precise molecular mechanism of pore formation. The formation of pores and their electrophysiologic characteristics were studied with planar lipid membranes. We show that amino acids at positions 1 and 3 of equinatoxin II are exposed to the lumen of the pore. Moreover, sulfhydryl reagents and a hexa-histidine tag attached to the N-terminus revealed that the N-terminus of the toxin extends through the pore to the other (trans) side of the membrane and that negatively charged residues inside the pore are crucial to define the electrophysiologic characteristics of the channel. Finally, we detected a new, less stable, state with a lower conductance by using a deletion mutant in which the first five N-terminal amino acids were removed. We propose that the first five amino acids help to anchor the amphipathic helix on the trans side of the membrane and consequently stabilize the final transmembrane pore.
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Affiliation(s)
- Katarina Kristan
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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17
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Dalla Serra M, Coraiola M, Viero G, Comai M, Potrich C, Ferreras M, Baba-Moussa L, Colin DA, Menestrina G, Bhakdi S, Prévost G. Staphylococcus aureus bicomponent gamma-hemolysins, HlgA, HlgB, and HlgC, can form mixed pores containing all components. J Chem Inf Model 2006; 45:1539-45. [PMID: 16309251 DOI: 10.1021/ci050175y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Staphylococcal gamma-hemolysins are bicomponent toxins forming a protein family with leucocidins and alpha-toxin. Two active toxins (AB and CB) can be formed combining one of the class-S components, HlgA or HlgC, with the class-F component HlgB. These two gamma-hemolysins form pores with marked similarities to alpha-toxin in terms of conductance, nonlinearity of the current-voltage curve, and channel stability in the open state. AB and CB pores, however, are cation-selective, whereas alpha-toxin is anion-selective. gamma-Hemolysins' pores are hetero-oligomers formed by three or four copies of each component (indicated as 3A3B and 3C3B or 4A4B and 4C4B). Point mutants located on a beta-strand of the class-S component that forms part of the protomer-protomer contact region can prevent oligomer assembly. Interestingly, these mutants inhibit growth of pores formed not only by their natural components but also by nonstandard components. This lead to the hypothesis that mixed ABC pores could also be formed. By studying the conductance of pores, assembled in the presence of all three components (in different ratios), it was observed that the magnitudes expected for mixed pores were, indeed, present. We conclude that the gamma-hemolysin/leucocidin bicomponent toxin family may form a larger than expected number of active toxins by cross-combining various S and F components.
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Affiliation(s)
- Mauro Dalla Serra
- Istituto Trentino di Cultura-Consiglio Nazionale delle Ricerche (ITC-CNR) Istituto di Biofisica, Via Sommarive 18, I-38050 Povo (Trento), Italy.
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18
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Joubert O, Viero G, Keller D, Martinez E, Colin D, Monteil H, Mourey L, Dalla serra M, Prévost G. Engineered covalent leucotoxin heterodimers form functional pores: insights into S-F interactions. Biochem J 2006; 396:381-9. [PMID: 16494579 PMCID: PMC1462717 DOI: 10.1042/bj20051878] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The staphylococcal alpha-toxin and bipartite leucotoxins belong to a single family of pore-forming toxins that are rich in beta-strands, although the stoichiometry and electrophysiological characteristics of their pores are different. The different known structures show a common beta-sandwich domain that plays a key role in subunit-subunit interactions, which could be targeted to inhibit oligomerization of these toxins. We used several cysteine mutants of both HlgA (gamma-haemolysin A) and HlgB (gamma-haemolysin B) to challenge 20 heterodimers linked by disulphide bridges. A new strategy was developed in order to obtain a good yield for S-S bond formation and dimer stabilization. Functions of the pores formed by 14 purified dimers were investigated on model membranes, i.e. planar lipid bilayers and large unilamellar vesicles, and on target cells, i.e. rabbit and human red blood cells and polymorphonuclear neutrophils. We observed that dimers HlgA T28C-HlgB N156C and HlgA T21C-HlgB T157C form pores with similar characteristics as the wild-type toxin, thus suggesting that the mutated residues are facing one another, allowing pore formation. Our results also confirm the octameric stoichiometry of the leucotoxin pores, as well as the parity of the two monomers in the pore. Correctly assembled heterodimers thus constitute the minimal functional unit of leucotoxins. We propose amino acids involved in interactions at one of the two interfaces for an assembled leucotoxin.
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Affiliation(s)
- Olivier Joubert
- *Laboratoire de Physiopathologie et d'Antibiologie Microbiennes, EA 3432, Institut de Bactériologie de la Faculté de Médecine (Université Louis Pasteur), Hôpitaux Universitaires de Strasbourg, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Gabriella Viero
- †ITC and CNR-IBF Unit at Trento, 18 Via Sommarive, I-38050 Povo (Trento), Italy
| | - Daniel Keller
- *Laboratoire de Physiopathologie et d'Antibiologie Microbiennes, EA 3432, Institut de Bactériologie de la Faculté de Médecine (Université Louis Pasteur), Hôpitaux Universitaires de Strasbourg, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Eric Martinez
- *Laboratoire de Physiopathologie et d'Antibiologie Microbiennes, EA 3432, Institut de Bactériologie de la Faculté de Médecine (Université Louis Pasteur), Hôpitaux Universitaires de Strasbourg, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Didier A. Colin
- *Laboratoire de Physiopathologie et d'Antibiologie Microbiennes, EA 3432, Institut de Bactériologie de la Faculté de Médecine (Université Louis Pasteur), Hôpitaux Universitaires de Strasbourg, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Henri Monteil
- *Laboratoire de Physiopathologie et d'Antibiologie Microbiennes, EA 3432, Institut de Bactériologie de la Faculté de Médecine (Université Louis Pasteur), Hôpitaux Universitaires de Strasbourg, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Lionel Mourey
- ‡Groupe de Biophysique Structurale, Département Mécanismes Moléculaires des Infections Mycobactériennes, CNRS-IPBS UMR 5089, 205 route de Narbonne, F-31077 Toulouse Cedex, France
| | - Mauro Dalla serra
- †ITC and CNR-IBF Unit at Trento, 18 Via Sommarive, I-38050 Povo (Trento), Italy
| | - Gilles Prévost
- *Laboratoire de Physiopathologie et d'Antibiologie Microbiennes, EA 3432, Institut de Bactériologie de la Faculté de Médecine (Université Louis Pasteur), Hôpitaux Universitaires de Strasbourg, 3 rue Koeberlé, F-67000 Strasbourg, France
- To whom correspondence should be addressed (email )
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19
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Viero G, Cunaccia R, Prévost G, Werner S, Monteil H, Keller D, Joubert O, Menestrina G, Dalla Serra M. Homologous versus heterologous interactions in the bicomponent staphylococcal gamma-haemolysin pore. Biochem J 2006; 394:217-25. [PMID: 16241903 PMCID: PMC1386019 DOI: 10.1042/bj20051210] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Staphylococcal gamma-haemolysin HlgA-HlgB forms a beta-barrel transmembrane pore in cells and in model membranes. The pore is formed by the oligomerization of two different proteins and a still debated number of monomers. To clarify the topology of the pore, we have mutated single residues - placed near the right and left interfaces of each monomer into cysteine. The mutants were labelled with fluorescent probes, forming a donor-acceptor pair for FRET (fluorescence resonance energy transfer). Heterologous couples (labelled on complementary left and right interfaces) displayed a marked FRET, suggesting extensive HlgA-HlgB or HlgB-HlgA contacts. Heterologous control couples (with both components labelled on the same side) showed absent or low FRET. We found the same result for the homologous couple formed by HlgA [i.e. HlgA-HlgA in the presence of wt (wild-type) HlgB]. The homologous HlgB couple (HlgB-HlgB labelled on left and right interfaces and in the presence of wt HlgA) displayed a transient, declining FRET, which may indicate fast formation of an intermediate that is consumed during pore formation. We conclude that bicomponent pores are assembled by alternating heterologous monomers.
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Affiliation(s)
- Gabriella Viero
- *Istituto Trentino di Cultura (ITC) and Consiglio Nazionale delle Ricerche (CNR), Istituto di Biofisica, Sezione di Trento, Via Sommarive 18, I-38050 Povo (TN), Italy
| | - Romina Cunaccia
- *Istituto Trentino di Cultura (ITC) and Consiglio Nazionale delle Ricerche (CNR), Istituto di Biofisica, Sezione di Trento, Via Sommarive 18, I-38050 Povo (TN), Italy
| | - Gilles Prévost
- †Institut de Bactériologie de la Faculté de Médecine, UPRES EA-3432, ULP-HUS, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Sandra Werner
- †Institut de Bactériologie de la Faculté de Médecine, UPRES EA-3432, ULP-HUS, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Henri Monteil
- †Institut de Bactériologie de la Faculté de Médecine, UPRES EA-3432, ULP-HUS, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Daniel Keller
- †Institut de Bactériologie de la Faculté de Médecine, UPRES EA-3432, ULP-HUS, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Olivier Joubert
- †Institut de Bactériologie de la Faculté de Médecine, UPRES EA-3432, ULP-HUS, 3 rue Koeberlé, F-67000 Strasbourg, France
| | - Gianfranco Menestrina
- *Istituto Trentino di Cultura (ITC) and Consiglio Nazionale delle Ricerche (CNR), Istituto di Biofisica, Sezione di Trento, Via Sommarive 18, I-38050 Povo (TN), Italy
| | - Mauro Dalla Serra
- *Istituto Trentino di Cultura (ITC) and Consiglio Nazionale delle Ricerche (CNR), Istituto di Biofisica, Sezione di Trento, Via Sommarive 18, I-38050 Povo (TN), Italy
- To whom correspondence should be addressed (email )
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20
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Pantano S, Montecucco C. A molecular model of the Vibrio cholerae cytolysin transmembrane pore. Toxicon 2005; 47:35-40. [PMID: 16330061 DOI: 10.1016/j.toxicon.2005.09.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Revised: 08/31/2005] [Accepted: 09/22/2005] [Indexed: 01/05/2023]
Abstract
The cytotoxic activity of some of the most pathogenic strains of Vibrio cholerae is associated with a cytolysin protein (VCC), which forms oligomeric transmembrane pores and changes the permeability of intestinal cells. We present here a model structure of the transmembrane pore of VCC based on sequence comparison with other pore-forming toxins. VCC is suggested to form a transmembrane beta-barrel pore with a relatively large trans vestibule region. Calculations of the electrostatic profile within the pore lumen provide a rationale for the low conductance and selectivity of the VCC ion channel.
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Affiliation(s)
- Sergio Pantano
- Venetian Institute of Molecular Medicine (VIMM),Via Orus 2, 35129, Padova, Italy.
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21
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Guillet V, Roblin P, Werner S, Coraiola M, Menestrina G, Monteil H, Prévost G, Mourey L. Crystal Structure of Leucotoxin S Component. J Biol Chem 2004; 279:41028-37. [PMID: 15262988 DOI: 10.1074/jbc.m406904200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Staphylococcal leucocidins and gamma-hemolysins (leucotoxins) are bi-component toxins that form lytic transmembrane pores. Their cytotoxic activities require the synergistic association of a class S component and a class F component, produced as water-soluble monomers that form hetero-oligomeric membrane-associated complexes. Strains that produce the Panton-Valentine leucocidin are clinically associated with cutaneous lesions and community-acquired pneumonia. In a previous study, we determined the crystal structure of the F monomer from the Panton-Valentine leucocidin. To derive information on the second component of the leucotoxins, the x-ray structure of the S protein from the Panton-Valentine leucocidin was solved to 2.0 angstrom resolution using a tetragonal crystal form that contains eight molecules in the asymmetric unit. The structure demonstrates the different conformation of the domain involved in membrane contacts and illustrates sequence and tertiary structure variabilities of the pore-forming leucotoxins. Mutagenesis studies at a key surface residue (Thr-28) further support the important role played by these microheterogeneities for the assembly of the bipartite leucotoxins.
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Affiliation(s)
- Valérie Guillet
- Groupe de Biophysique Structurale, Département Mécanismes Moléculaires des Infections Mycobactériennes, CNRS-IPBS, 205 route de Narbonne, 31077 Toulouse Cedex, France
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22
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Nguyen VT, Kamio Y, Higuchi H. Single-molecule imaging of cooperative assembly of gamma-hemolysin on erythrocyte membranes. EMBO J 2003; 22:4968-79. [PMID: 14517236 PMCID: PMC204481 DOI: 10.1093/emboj/cdg498] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Single-molecule fluorescence imaging was used to investigate assembly of Staphylococcus aureus LukF and HS monomers into pore-forming oligomers (gamma-hemolysin) on erythrocyte membranes. We distinguished the hetero-oligomers from the monomers, as indicated by fluorescence resonance energy transfer between different dyes attached to monomeric subunits. The stoichiometry of LukF (donor) and HS (acceptor) subunits in oligomers was deduced from the acceptor emission intensities during energy transfer and by direct acceptor excitation, respectively. Based on populations of monomeric and oligomeric intermediates, we estimated 11 sequential equilibrium constants for the assembly pathway, beginning with membrane binding of monomers, proceeding through single pore oligomerization, and culminating in the formation of clusters of pores. Several stages are highly cooperative, critically enhancing the efficiency of assembly.
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Affiliation(s)
- Vananh T Nguyen
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan
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23
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Menestrina G, Dalla Serra M, Comai M, Coraiola M, Viero G, Werner S, Colin DA, Monteil H, Prévost G. Ion channels and bacterial infection: the case of beta-barrel pore-forming protein toxins of Staphylococcus aureus. FEBS Lett 2003; 552:54-60. [PMID: 12972152 DOI: 10.1016/s0014-5793(03)00850-0] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Staphylococcus aureus strains causing human pathologies produce several toxins, including a pore-forming protein family formed by the single-component alpha-hemolysin and the bicomponent leukocidins and gamma-hemolysins. The last comprise two protein elements, S and F, that co-operatively form the active toxin. alpha-Hemolysin is always expressed by S. aureus strains, whereas bicomponent leukotoxins are more specifically involved in a few diseases. X-ray crystallography of the alpha-hemolysin pore has shown it is a mushroom-shaped, hollow heptamer, almost entirely consisting of beta-structure. Monomeric F subunits have a very similar core structure, except for the transmembrane stem domain which has to refold during pore formation. Large deletions in this domain abolished activity, whereas shorter deletions sometimes improved it, possibly by removing some of the interactions stabilizing the folded structure. Even before stem extension is completed, the formation of an oligomeric pre-pore can trigger Ca(2+)-mediated activation of some white cells, initiating an inflammatory response. Within the bicomponent toxins, gamma-hemolysins define three proteins (HlgA, HlgB, HlgC) that can generate two toxins: HlgA+HlgB and HlgC+HlgB. Like alpha-hemolysin they form pores in planar bilayers with similar conductance, but opposite selectivity (cation instead of anion) for the presence of negative charges in the ion pathway. gamma-Hemolysin pores seem to be organized as alpha-hemolysin, but should contain an even number of each component, alternating in a 1:1 stoichiometry.
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Affiliation(s)
- G Menestrina
- CNR-ITC Istituto di Biofisica, Sezione di Trento, Via Sommarive 18, I-38050 Povo, Italy.
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24
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Alouf JE. Molecular features of the cytolytic pore-forming bacterial protein toxins. Folia Microbiol (Praha) 2003; 48:5-16. [PMID: 12744072 DOI: 10.1007/bf02931271] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The repertoire of the cytolytic pore-forming protein toxins (PFT) comprises 81 identified members. The essential feature of these cytolysins is their capacity to provoke the formation of hydrophilic pores in the cytoplasmic membranes of target eukaryotic cells. This process results from the binding of the proteins on the cell surface, followed by their oligomerization which leads to the insertion of the oligomers into the membrane and formation of protein-lined channels. It impairs the osmotic balance of the cell and causes cytolysis. In this review the molecular aspects of a number of important PFT and their respective encoding structural genes will be briefly described.
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Affiliation(s)
- J E Alouf
- Institut Pasteur, 75 015 Paris, France.
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