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Šolinc G, Švigelj T, Omersa N, Snoj T, Pirc K, Žnidaršič N, Yamaji-Hasegawa A, Kobayashi T, Anderluh G, Podobnik M. Pore-forming moss protein bryoporin is structurally and mechanistically related to actinoporins from evolutionarily distant cnidarians. J Biol Chem 2022; 298:102455. [PMID: 36063994 PMCID: PMC9526159 DOI: 10.1016/j.jbc.2022.102455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/29/2022] [Accepted: 08/29/2022] [Indexed: 10/26/2022] Open
Abstract
Pore-forming proteins perforate lipid membranes and consequently affect their integrity and cell fitness. Therefore, it is not surprising that many of these proteins from bacteria, fungi, or certain animals act as toxins. While pore-forming proteins have also been found in plants, there is little information on their molecular structure and mode of action. Bryoporin is a protein from the moss Physcomitrium patens, and its corresponding gene was found to be upregulated by various abiotic stresses, especially dehydration, as well as upon fungal infection. Based on the amino acid sequence, it was suggested that bryoporin was related to the actinoporin family of pore-forming proteins, originally discovered in sea anemones. Here, we provide the first detailed structural and functional analysis of this plant cytolysin. The crystal structure of the monomeric bryoporin is highly similar to those of actinoporins. Our cryo-EM analysis of its pores showed an actinoporin-like octameric structure, thereby revealing a close kinship of proteins from evolutionarily distant organisms. This was further confirmed by our observation of bryoporin's preferential binding to and formation of pores in membranes containing animal sphingolipids, such as sphingomyelin and ceramide phosphoethanolamine; however, its binding affinity was weaker than that of actinoporin equinatoxin II. We determined bryoporin did not bind to major sphingolipids found in fungi or plants, and its membrane-binding and pore-forming activity were enhanced by various sterols. Our results suggest that bryoporin could represent a part of the moss defense arsenal, acting as a pore-forming toxin against membranes of potential animal pathogens, parasites, or predators.
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Affiliation(s)
- Gašper Šolinc
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Tomaž Švigelj
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Neža Omersa
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Tina Snoj
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Katja Pirc
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Nada Žnidaršič
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana, Slovenia
| | | | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; UMR 7021 CNRS, Université de Strasbourg, Illkirch, France
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia
| | - Marjetka Podobnik
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia.
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Palacios-Ortega J, García-Linares S, Rivera-de-Torre E, Heras-Márquez D, Gavilanes JG, Slotte JP, Martínez-Del-Pozo Á. Structural foundations of sticholysin functionality. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140696. [PMID: 34246789 DOI: 10.1016/j.bbapap.2021.140696] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/05/2021] [Accepted: 07/06/2021] [Indexed: 01/22/2023]
Abstract
Actinoporins constitute a family of α pore-forming toxins produced by sea anemones. The soluble fold of these proteins consists of a β-sandwich flanked by two α-helices. Actinoporins exert their activity by specifically recognizing sphingomyelin at their target membranes. Once there, they penetrate the membrane with their N-terminal α-helices, a process that leads to the formation of cation-selective pores. These pores kill the target cells by provoking an osmotic shock on them. In this review, we examine the role and relevance of the structural features of actinoporins, down to the residue level. We look at the specific amino acids that play significant roles in the function of actinoporins and their fold. Particular emphasis is given to those residues that display a high degree of conservation across the actinoporin sequences known to date. In light of the latest findings in the field, the membrane requirements for pore formation, the effect of lipid composition, and the process of pore formation are also discussed.
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Affiliation(s)
- Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain; Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.
| | - Sara García-Linares
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - Esperanza Rivera-de-Torre
- Department of Biochemistry and Biotechnology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Diego Heras-Márquez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
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3
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Johnstone BA, Christie MP, Morton CJ, Parker MW. X-ray crystallography shines a light on pore-forming toxins. Methods Enzymol 2021; 649:1-46. [PMID: 33712183 DOI: 10.1016/bs.mie.2021.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A common form of cellular attack by pathogenic bacteria is to secrete pore-forming toxins (PFTs). Capable of forming transmembrane pores in various biological membranes, PFTs have also been identified in a diverse range of other organisms such as sea anemones, earthworms and even mushrooms and trees. The mechanism of pore formation by PFTs is associated with substantial conformational changes in going from the water-soluble to transmembrane states of the protein. The determination of the crystal structures for numerous PFTs has shed much light on our understanding of these proteins. Other than elucidating the atomic structural details of PFTs and the conformational changes that must occur for pore formation, crystal structures have revealed structural homology that has led to the discovery of new PFTs and new PFT families. Here we review some key crystallographic results together with complimentary approaches for studying PFTs. We discuss how these studies have impacted our understanding of PFT function and guided research into biotechnical applications.
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Affiliation(s)
- Bronte A Johnstone
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michelle P Christie
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Craig J Morton
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Michael W Parker
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia; St. Vincent's Institute of Medical Research, Fitzroy, VIC, Australia.
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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.
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Mondal AK, Verma P, Lata K, Singh M, Chatterjee S, Chattopadhyay K. Sequence Diversity in the Pore-Forming Motifs of the Membrane-Damaging Protein Toxins. J Membr Biol 2020; 253:469-478. [PMID: 32955633 DOI: 10.1007/s00232-020-00141-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 09/08/2020] [Indexed: 12/21/2022]
Abstract
Pore-forming proteins/toxins (PFPs/PFTs) are the distinct class of membrane-damaging proteins. They act by forming oligomeric pores in the plasma membranes. PFTs and PFPs from diverse organisms share a common mechanism of action, in which the designated pore-forming motifs of the membrane-bound protein molecules insert into the membrane lipid bilayer to create the water-filled pores. One common characteristic of these pore-forming motifs is that they are amphipathic in nature. In general, the hydrophobic sidechains of the pore-forming motifs face toward the hydrophobic core of the membranes, while the hydrophilic residues create the lining of the water-filled pore lumen. Interestingly, pore-forming motifs of the distinct subclass of PFPs/PFTs share very little sequence similarity with each other. Therefore, the common guiding principle that governs the sequence-to-structure paradigm in the mechanism of action of these PFPs/PFTs still remains an enigma. In this article, we discuss this notion using the examples of diverse groups of membrane-damaging PFPs/PFTs.
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Affiliation(s)
- Anish Kumar Mondal
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Pratima Verma
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Kusum Lata
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Mahendra Singh
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Shamaita Chatterjee
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli, Mohali, Punjab, 140306, India.
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Pore-Forming Proteins from Cnidarians and Arachnids as Potential Biotechnological Tools. Toxins (Basel) 2019; 11:toxins11060370. [PMID: 31242582 PMCID: PMC6628452 DOI: 10.3390/toxins11060370] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/18/2019] [Accepted: 06/21/2019] [Indexed: 12/31/2022] Open
Abstract
Animal venoms are complex mixtures of highly specialized toxic molecules. Cnidarians and arachnids produce pore-forming proteins (PFPs) directed against the plasma membrane of their target cells. Among PFPs from cnidarians, actinoporins stand out for their small size and molecular simplicity. While native actinoporins require only sphingomyelin for membrane binding, engineered chimeras containing a recognition antibody-derived domain fused to an actinoporin isoform can nonetheless serve as highly specific immunotoxins. Examples of such constructs targeted against malignant cells have been already reported. However, PFPs from arachnid venoms are less well-studied from a structural and functional point of view. Spiders from the Latrodectus genus are professional insect hunters that, as part of their toxic arsenal, produce large PFPs known as latrotoxins. Interestingly, some latrotoxins have been identified as potent and highly-specific insecticides. Given the proteinaceous nature of these toxins, their promising future use as efficient bioinsecticides is discussed throughout this Perspective. Protein engineering and large-scale recombinant production are critical steps for the use of these PFPs as tools to control agriculturally important insect pests. In summary, both families of PFPs, from Cnidaria and Arachnida, appear to be molecules with promising biotechnological applications.
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An aromatic cluster in Lysinibacillus sphaericus BinB involved in toxicity and proper in-membrane folding. Arch Biochem Biophys 2018; 660:29-35. [PMID: 30321498 DOI: 10.1016/j.abb.2018.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 10/09/2018] [Accepted: 10/11/2018] [Indexed: 12/29/2022]
Abstract
The binary toxin from Lysinibacillus sphaericus has been successfully used for controlling mosquito-transmitted diseases. Based on structural alignments with other toxins, an aromatic cluster in the C-terminal domain of BinB (termed here BC) has been proposed to be important for toxicity. We tested this experimentally using BinB mutants bearing single mutations in this aromatic cluster. Consistent with the hypothesis, two of these mutations, F311A and F315A, were not toxic to Culex quinquefasciatus larvae and were unable to permeabilize liposomes or elicit ion channel activity, in contrast to wild-type BinB. Despite these effects, none of these mutations altered significantly the interaction between the activated forms of the two subunits in solution. These results indicate that these aromatic residues on the C-terminal domain of BinB are critical for toxin insertion in membranes. The latter can be by direct contact of these residues with the membrane surface, or by facilitating the formation a membrane-inserting oligomer.
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Carretero GPB, Vicente EF, Cilli EM, Alvarez CM, Jenssen H, Schreier S. Dissecting the mechanism of action of actinoporins. Role of the N-terminal amphipathic α-helix in membrane binding and pore activity of sticholysins I and II. PLoS One 2018; 13:e0202981. [PMID: 30161192 PMCID: PMC6117003 DOI: 10.1371/journal.pone.0202981] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 08/13/2018] [Indexed: 11/19/2022] Open
Abstract
Actinoporins sticholysin I and sticholysin II (St I, St II) are proposed to lyse model and biomembranes via toroidal pore formation by their N-terminal domain. Based on the hypothesis that peptide fragments can reproduce the structure and function of this domain, the behavior of peptides containing St I residues 12–31 (StI12-31), St II residues 11–30 (StII11-30), and its TOAC-labeled analogue (N-TOAC-StII11-30) was examined. Molecular modeling showed a good match with experimental structures, indicating amphipathic α-helices in the same regions as in the toxins. CD spectra revealed that the peptides were essentially unstructured in aqueous solution, acquiring α-helical conformation upon interaction with micelles and large unilamellar vesicles (LUV) of variable lipid composition. Fluorescence quenching studies with NBD-containing lipids indicated that N-TOAC-StII11-30’s nitroxide moiety is located in the membranes polar head group region. Pyrene-labeled phospholipid inter-leaflet redistribution suggested that the peptides form toroidal pores, according to the mechanism of action proposed for the toxins. Binding occurred only to negatively charged LUV, indicating the importance of electrostatic interactions; in contrast the peptides bound to both negatively charged and zwitterionic micelles, pointing to a lesser influence of these interactions. In addition, differences between bilayers and micelles in head group packing and in curvature led to differences in peptide-membrane interaction. We propose that the peptides topography in micelles resembles that of the toxins in the toroidal pore. The peptides mimicked the toxins permeabilizing activity, St II peptides being more effective than StI12-31. To our knowledge, this is the first demonstration that differences in the toxins N-terminal amphipathic α-helix play a role in the difference between St I and St II activities.
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Affiliation(s)
- Gustavo P. B. Carretero
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Eduardo F. Vicente
- Faculty of Science and Engineering, State University of São Paulo, Tupã, Brazil
| | - Eduardo M. Cilli
- Institute of Chemistry, State University of São Paulo, Araraquara, Brazil
| | | | - Håvard Jenssen
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Shirley Schreier
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
- * E-mail:
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Tsutsui K, Sato T. Identification of the two new, functional actinoporins, CJTOX I and CJTOX II, from the deep-sea anemone Cribrinopsis japonica. Toxicon 2018; 148:40-49. [PMID: 29649486 DOI: 10.1016/j.toxicon.2018.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 03/23/2018] [Accepted: 04/05/2018] [Indexed: 11/30/2022]
Abstract
Actinoporins are pore-forming proteins found in sea anemones. Although we now have a large collection of data on actinoporins, our knowledge is based heavily on those identified in shallow-water anemones. Because the deep sea differs considerably from shallow waters in hydrostatic pressures, temperatures, and the prey composition, the deep-sea actinoporin may have evolved in unique ways. This study, therefore, aimed to obtain new actinoporins in the deep-sea anemone Cribrinopis japonica (Actiniaria, Actiniidae). An actinoporin-like sequence was identified from the previously established C. japonica RNA-Seq database, and the complete length (663 bp) of the deep-sea actinoporin gene, Cjtox I, was obtained. In addition, a similar gene, Cjtox II (666 bp), was also identified from RNA of actinopharynx. CJTOX I and CJTOX II were similar in their primary structures, but CJTOX I lacked one residue in the middle of the protein. There was also a difference in the gene expression in live animals, where only Cjtox I was expressed in tentacles of C. japonica. In the heterologous expression where BL21 (DE3) strain was retransformed with the plasmid containing either Cjtox I or Cjtox II gene, the supernatants of both cell lysates showed hemolytic activity on the equine erythrocytes. Preincubation of the supernatants with sphingomyelin caused reduced activity, implying that the CJTOX I and II would target sphingomyelin as with other actinoporins. Because of the structures similarity to the known actinoporins and the sphingomyelin-inhibitable hemolytic activity, both CJTOX I and II were concluded to be new actinoporins, which were identified for the first time from a deep-sea anemone.
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Affiliation(s)
- Kenta Tsutsui
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027, Japan
| | - Tomomi Sato
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027, Japan.
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Lima de Oliveira A, Maffud Cilli E, Ros U, Crusca E, Lanio ME, Alvarez C, Schreier S, Aguiar Pertinhez T, Spisni A. Insights on the structure-activity relationship of peptides derived from Sticholysin II. Biopolymers 2018; 110. [PMID: 29359791 DOI: 10.1002/bip.23097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 11/26/2017] [Accepted: 12/03/2017] [Indexed: 02/06/2023]
Abstract
Sticholysin II (StII) is a pore-forming actinoporin from the sea anemone Stichodactyla helianthus. A mechanistic model of its action has been proposed: proteins bind to cell membrane, insert their N-termini into the lipid core and assemble into homo-tetramer pores responsible for host-cell death. Because very likely the first 10 residues of StII N-terminus are critical for membrane penetration, to dissect the molecular details of that functionality, we studied two synthetic peptides: StII1-30 and StII16-35 . They show diverse haemolytic and candidacidal activity that correlate with distinct orientations in SDS micelles. NMR shows that StII1-30 partly inserts into the micelle, while StII16-35 lays on the micelle surface. These results justify the diverse concentration dependence of their candidacidal activity supposing a different mechanism of action and providing new hints on StII lytic activity at molecular level. Biotechnological application of these peptides, focused on the development of therapeutic immunocomplexes, may be envisaged.
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Affiliation(s)
- Aline Lima de Oliveira
- Institute of Chemistry, University of Brasilia, Brasilia, DF, Brazil
- Department of Biochemistry and Chemical Technology, Institute of Chemistry, São Paulo State University, Araraquara, Brazil
| | | | - Uris Ros
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Edson Crusca
- Center for Protein Studies, Biology Faculty, University of Havana, Havana, Cuba
| | - María Eliana Lanio
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Carlos Alvarez
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
- Department of Medicine and Surgery, Unit of Biochemistry, University of Parma, Parma, Italy
| | - Shirley Schreier
- Department of Medicine and Surgery, Unit of Biochemistry, University of Parma, Parma, Italy
| | - Thelma Aguiar Pertinhez
- Department of Biochemistry and Chemical Technology, Institute of Chemistry, São Paulo State University, Araraquara, Brazil
- Transfusion Medicine Unit, AUSL - IRCCS Reggio Emilia, Italy
| | - Alberto Spisni
- Department of Biochemistry and Chemical Technology, Institute of Chemistry, São Paulo State University, Araraquara, Brazil
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11
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Biophysical and biochemical strategies to understand membrane binding and pore formation by sticholysins, pore-forming proteins from a sea anemone. Biophys Rev 2017; 9:529-544. [PMID: 28853034 DOI: 10.1007/s12551-017-0316-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/08/2017] [Indexed: 10/19/2022] Open
Abstract
Actinoporins constitute a unique class of pore-forming toxins found in sea anemones that are able to bind and oligomerize in membranes, leading to cell swelling, impairment of ionic gradients and, eventually, to cell death. In this review we summarize the knowledge generated from the combination of biochemical and biophysical approaches to the study of sticholysins I and II (Sts, StI/II), two actinoporins largely characterized by the Center of Protein Studies at the University of Havana during the last 20 years. These approaches include strategies for understanding the toxin structure-function relationship, the protein-membrane association process leading to pore formation and the interaction of toxin with cells. The rational combination of experimental and theoretical tools have allowed unraveling, at least partially, of the complex mechanisms involved in toxin-membrane interaction and of the molecular pathways triggered upon this interaction. The study of actinoporins is important not only to gain an understanding of their biological roles in anemone venom but also to investigate basic molecular mechanisms of protein insertion into membranes, protein-lipid interactions and the modulation of protein conformation by lipid binding. A deeper knowledge of the basic molecular mechanisms involved in Sts-cell interaction, as described in this review, will support the current investigations conducted by our group which focus on the design of immunotoxins against tumor cells and antigen-releasing systems to cell cytosol as Sts-based vaccine platforms.
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Cabezas S, Ho S, Ros U, Lanio ME, Alvarez C, van der Goot FG. Damage of eukaryotic cells by the pore-forming toxin sticholysin II: Consequences of the potassium efflux. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:982-992. [PMID: 28173991 DOI: 10.1016/j.bbamem.2017.02.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/06/2017] [Accepted: 02/03/2017] [Indexed: 01/17/2023]
Abstract
Pore-forming toxins (PFTs) form holes in membranes causing one of the most catastrophic damages to a target cell. Target organisms have evolved a regulated response against PFTs damage including cell membrane repair. This ability of cells strongly depends on the toxin concentration and the properties of the pores. It has been hypothesized that there is an inverse correlation between the size of the pores and the time required to repair the membrane, which has been for long a non-intuitive concept and far to be completely understood. Moreover, there is a lack of information about how cells react to the injury triggered by eukaryotic PFTs. Here, we investigated some molecular events related with eukaryotic cells response against the membrane damage caused by sticholysin II (StII), a eukaryotic PFT produced by a sea anemone. We evaluated the change in the cytoplasmic potassium, identified the main MAPK pathways activated after pore-formation by StII, and compared its effect with those from two well-studied bacterial PFTs: aerolysin and listeriolysin O (LLO). Strikingly, we found that membrane recovery upon StII damage takes place in a time scale similar to LLO in spite of the fact that they form pores by far different in size. Furthermore, our data support a common role of the potassium ion, as well as MAPKs in the mechanism that cells use to cope with these toxins injury.
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Affiliation(s)
- Sheila Cabezas
- Center for Protein Studies, Faculty of Biology, Havana University, Street 25 # 455, CP 10400, Havana, Cuba.
| | - Sylvia Ho
- École Polytechnique Fédérale de Lausanne, Global Health Institution, Faculty of Life Sciences, Station 15, CH 1015 Lausanne, Switzerland.
| | - Uris Ros
- Center for Protein Studies, Faculty of Biology, Havana University, Street 25 # 455, CP 10400, Havana, Cuba; Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe Seyler Strasse, 4, 72076, Tübingen, Germany.
| | - María E Lanio
- Center for Protein Studies, Faculty of Biology, Havana University, Street 25 # 455, CP 10400, Havana, Cuba.
| | - Carlos Alvarez
- Center for Protein Studies, Faculty of Biology, Havana University, Street 25 # 455, CP 10400, Havana, Cuba.
| | - F Gisou van der Goot
- École Polytechnique Fédérale de Lausanne, Global Health Institution, Faculty of Life Sciences, Station 15, CH 1015 Lausanne, Switzerland.
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García-Linares S, Rivera-de-Torre E, Palacios-Ortega J, Gavilanes JG, Martínez-del-Pozo Á. The Metamorphic Transformation of a Water-Soluble Monomeric Protein Into an Oligomeric Transmembrane Pore. ADVANCES IN BIOMEMBRANES AND LIPID SELF-ASSEMBLY 2017. [DOI: 10.1016/bs.abl.2017.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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14
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Wacklin HP, Bremec BB, Moulin M, Rojko N, Haertlein M, Forsyth T, Anderluh G, Norton RS. Neutron reflection study of the interaction of the eukaryotic pore-forming actinoporin equinatoxin II with lipid membranes reveals intermediate states in pore formation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:640-52. [DOI: 10.1016/j.bbamem.2015.12.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 11/02/2015] [Accepted: 12/15/2015] [Indexed: 01/07/2023]
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15
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Weber DK, Yao S, Rojko N, Anderluh G, Lybrand TP, Downton MT, Wagner J, Separovic F. Characterization of the Lipid-Binding Site of Equinatoxin II by NMR and Molecular Dynamics Simulation. Biophys J 2016; 108:1987-96. [PMID: 25902438 DOI: 10.1016/j.bpj.2015.03.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 03/09/2015] [Accepted: 03/12/2015] [Indexed: 12/26/2022] Open
Abstract
Equinatoxin II (EqtII) is a soluble, 20 kDa pore-forming protein toxin isolated from the sea anemone Actinia equina. Although pore formation has long been known to occur in distinct stages, including monomeric attachment to phospholipid membranes followed by detachment of the N-terminal helical domain and oligomerization into the final pore assembly, atomistic-level detail of the protein-lipid interactions underlying these events remains elusive. Using high-resolution solution state NMR of uniformly-(15)N-labeled EqtII at the critical micelle concentration of dodecylphosphocholine, we have mapped the lipid-binding site through chemical shift perturbations. Subsequent docking of an EqtII monomer onto a dodecylphosphocholine micelle, followed by 400 ns of all-atom molecular dynamics simulation, saw several high-occupancy lipid-binding pockets stabilized by cation-π, hydrogen bonding, and hydrophobic interactions; and stabilization of the loop housing the conserved arginine-glycine-aspartate motif. Additional simulation of EqtII with an N-acetyl sphingomyelin micelle, for which high-resolution NMR data cannot be obtained due to aggregate formation, revealed that sphingomyelin specificity might occur via hydrogen bonding to the 3-OH and 2-NH groups unique to the ceramide backbone by side chains of D109 and Y113; and main chains of P81 and W112. Furthermore, a binding pocket formed by K30, K77, and P81, proximate to the hinge region of the N-terminal helix, was identified and may be implicated in triggering pore formation.
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Affiliation(s)
- Daniel K Weber
- School of Chemistry, University of Melbourne, Victoria, Australia; Bio21 Institute, University of Melbourne, Victoria, Australia
| | - Shenggen Yao
- Bio21 Institute, University of Melbourne, Victoria, Australia
| | - Nejc Rojko
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Gregor Anderluh
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Terry P Lybrand
- Center for Structural Biology, Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Matthew T Downton
- IBM Research Collaboratory for Life Sciences, Victorian Life Sciences Computation Initiative, University of Melbourne, Victoria, Australia
| | - John Wagner
- IBM Research Collaboratory for Life Sciences, Victorian Life Sciences Computation Initiative, University of Melbourne, Victoria, Australia
| | - Frances Separovic
- School of Chemistry, University of Melbourne, Victoria, Australia; Bio21 Institute, University of Melbourne, Victoria, Australia.
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16
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Rojko N, Dalla Serra M, Maček P, Anderluh G. Pore formation by actinoporins, cytolysins from sea anemones. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:446-56. [PMID: 26351738 DOI: 10.1016/j.bbamem.2015.09.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/31/2015] [Accepted: 09/02/2015] [Indexed: 11/30/2022]
Abstract
Actinoporins (APs) from sea anemones are ~20 kDa pore forming toxins with a β-sandwich structure flanked by two α-helices. The molecular mechanism of APs pore formation is composed of several well-defined steps. APs bind to membrane by interfacial binding site composed of several aromatic amino acid residues that allow binding to phosphatidylcholine and specific recognition of sphingomyelin. Subsequently, the N-terminal α-helix from the β-sandwich has to be inserted into the lipid/water interphase in order to form a functional pore. Functional studies and single molecule imaging revealed that only several monomers, 3-4, oligomerise to form a functional pore. In this model the α-helices and surrounding lipid molecules build toroidal pore. In agreement, AP pores are transient and electrically heterogeneous. On the contrary, crystallized oligomers of actinoporin fragaceatoxin C were found to be composed of eight monomers with no lipids present between the adjacent α-helices. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Maur Dalla Serra and Franco Gambale.
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Affiliation(s)
- Nejc Rojko
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Mauro Dalla Serra
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche & Fondazione Bruno Kessler, via alla Cascata 56/C, 38123 Trento, Italy
| | - Peter Maček
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
| | - Gregor Anderluh
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia; Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
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17
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Mutagenesis and functional analysis of the pore-forming toxin HALT-1 from Hydra magnipapillata. Toxins (Basel) 2015; 7:407-22. [PMID: 25654788 PMCID: PMC4344632 DOI: 10.3390/toxins7020407] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 01/27/2015] [Indexed: 12/02/2022] Open
Abstract
Actinoporins are small 18.5 kDa pore-forming toxins. A family of six actinoporin genes has been identified in the genome of Hydra magnipapillata, and HALT-1 (Hydra actinoporin-like toxin-1) has been shown to have haemolytic activity. In this study, we have used site-directed mutagenesis to investigate the role of amino acids in the pore-forming N-terminal region and the conserved aromatic cluster required for cell membrane binding. A total of 10 mutants of HALT-1 were constructed and tested for their haemolytic and cytolytic activity on human erythrocytes and HeLa cells, respectively. Insertion of 1–4 negatively charged residues in the N-terminal region of HALT-1 strongly reduced haemolytic and cytolytic activity, suggesting that the length or charge of the N-terminal region is critical for pore-forming activity. Moreover, substitution of amino acids in the conserved aromatic cluster reduced haemolytic and cytolytic activity by more than 80%, suggesting that these aromatic amino acids are important for attachment to the lipid membrane as shown for other actinoporins. The results suggest that HALT-1 and other actinoporins share similar mechanisms of pore formation and that it is critical for HALT-1 to maintain an amphipathic helix at the N-terminus and an aromatic amino acid-rich segment at the site of membrane binding.
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18
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Antonini V, Pérez-Barzaga V, Bampi S, Pentón D, Martínez D, Serra MD, Tejuca M. Functional characterization of sticholysin I and W111C mutant reveals the sequence of the actinoporin's pore assembly. PLoS One 2014; 9:e110824. [PMID: 25350457 PMCID: PMC4211696 DOI: 10.1371/journal.pone.0110824] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 09/19/2014] [Indexed: 12/20/2022] Open
Abstract
The use of pore-forming toxins in the construction of immunotoxins against tumour cells is an alternative for cancer therapy. In this protein family one of the most potent toxins are the actinoporins, cytolysins from sea anemones. We work on the construction of tumour proteinase-activated immunotoxins using sticholysin I (StI), an actinoporin isolated from the sea anemone Stichodactyla helianthus. To accomplish this objective, recombinant StI (StIr) with a mutation in the membrane binding region has been employed. In this work, it was evaluated the impact of mutating tryptophan 111 to cysteine on the toxin pore forming capability. StI W111C is still able to permeabilize erythrocytes and liposomes, but at ten-fold higher concentration than StI. This is due to its lower affinity for the membrane, which corroborates the importance of residue 111 for the binding of actinoporins to the lipid bilayer. In agreement, other functional characteristics not directly associated to the binding, are essentially the same for both variants, that is, pores have oligomeric structures with similar radii, conductance, cation-selectivity, and instantaneous current-voltage behavior. In addition, this work provides experimental evidence sustaining the toroidal protein-lipid actinoporins lytic structures, since the toxins provoke the trans-bilayer movement (flip-flop) of a pyrene-labeled analogue of phosphatidylcholine in liposomes, indicating the existence of continuity between the outer and the inner membrane leaflet. Finally, our planar lipid membranes results have also contributed to a better understanding of the actinoporin's pore assembly mechanism. After the toxin binding and the N-terminal insertion in the lipid membrane, the pore assembly occurs by passing through different transient sub-conductance states. These states, usually 3 or 4, are due to the successive incorporation of N-terminal α-helices and lipid heads to the growing pores until a stable toroidal oligomeric structure is formed, which is mainly tetrameric.
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Affiliation(s)
- Valeria Antonini
- National Research Council of Italy - Institute of Biophysics and Bruno Kessler Foundation, Trento, Italy
| | - Victor Pérez-Barzaga
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, Ciudad de La Habana, Cuba
| | - Silvia Bampi
- National Research Council of Italy - Institute of Biophysics and Bruno Kessler Foundation, Trento, Italy
| | - David Pentón
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, Ciudad de La Habana, Cuba
| | - Diana Martínez
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, Ciudad de La Habana, Cuba
| | - Mauro Dalla Serra
- National Research Council of Italy - Institute of Biophysics and Bruno Kessler Foundation, Trento, Italy
- * E-mail: (MDS); (MT)
| | - Mayra Tejuca
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, Ciudad de La Habana, Cuba
- * E-mail: (MDS); (MT)
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19
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Baker MAB, Rojko N, Cronin B, Anderluh G, Wallace MI. Photobleaching Reveals Heterogeneous Stoichiometry for Equinatoxin II Oligomers. Chembiochem 2014; 15:2139-45. [DOI: 10.1002/cbic.201300799] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Indexed: 01/19/2023]
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20
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García-Linares S, Richmond R, García-Mayoral MF, Bustamante N, Bruix M, Gavilanes JG, Martínez-del-Pozo Á. The sea anemone actinoporin (Arg-Gly-Asp) conserved motif is involved in maintaining the competent oligomerization state of these pore-forming toxins. FEBS J 2014; 281:1465-1478. [DOI: 10.1111/febs.12717] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 12/12/2013] [Accepted: 12/31/2013] [Indexed: 01/19/2023]
Affiliation(s)
- Sara García-Linares
- Departamento de Bioquímica y Biología Molecular I; Facultad de Ciencias Químicas; Universidad Complutense; Madrid Spain
| | - Ryan Richmond
- Departamento de Bioquímica y Biología Molecular I; Facultad de Ciencias Químicas; Universidad Complutense; Madrid Spain
| | | | | | - Marta Bruix
- Instituto de Química-Física Rocasolano; Madrid Spain
| | - José G. Gavilanes
- Departamento de Bioquímica y Biología Molecular I; Facultad de Ciencias Químicas; Universidad Complutense; Madrid Spain
| | - Álvaro Martínez-del-Pozo
- Departamento de Bioquímica y Biología Molecular I; Facultad de Ciencias Químicas; Universidad Complutense; Madrid Spain
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21
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López-Castilla A, Pazos F, Schreier S, Pires JR. Solution NMR analysis of the interaction between the actinoporin sticholysin I and DHPC micelles--correlation with backbone dynamics. Proteins 2013; 82:1022-34. [PMID: 24218049 DOI: 10.1002/prot.24475] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 10/26/2013] [Accepted: 11/04/2013] [Indexed: 11/08/2022]
Abstract
Sticholysin I (StI), an actinoporin expressed as a water-soluble protein by the sea anemone Stichodactyla helianthus, binds to natural and model membranes, forming oligomeric pores. It is proposed that the first event of a multistep pore formation mechanism consists of the monomeric protein attachment to the lipid bilayer. To date there is no high-resolution structure of the actinoporin pore or other membrane-bound form available. Here we evaluated StI:micelle complexes of variable lipid composition to look for a suitable model for NMR studies. Micelles of pure or mixed lysophospholipids and of dihexanoyl phosphatidylcholine (DHPC) were examined. The StI:DHPC micelle was found to be the best system, yielding a stable sample and good quality spectra. A comprehensive chemical shift perturbation analysis was performed to map the StI membrane recognition site in the presence of DHPC micelles. The region mapped (residues F(51), R(52), S(53) in loop 3; F(107), D(108), Y(109), W(111), Y(112), W(115) in loop 7; Q(129), Y(132), D(134), M(135), Y(136), Y(137), G(138) in helix-α2) is in agreement with previously reported data, but additional residues were found to interact, especially residues V(81), A(82), T(83), G(84) in loop 5, and A(85), A(87) in strand-β5. Backbone dynamics measurements of StI free in solution and bound to micelles highlighted the relevance of protein flexibility for membrane binding and suggested that a conformer selection process may take place during protein-membrane interaction. We conclude that the StI:DHPC micelles system is a suitable model for further characterization of an actinoporin membrane-bound form by solution NMR.
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Affiliation(s)
- Aracelys López-Castilla
- Centro de Estudio de Proteinas, Facultad de Biologia, Universidad de la Habana, Habana, Cuba; Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
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22
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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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23
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Bavdek A, Kostanjšek R, Antonini V, Lakey JH, Dalla Serra M, Gilbert RJC, Anderluh G. pH dependence of listeriolysin O aggregation and pore-forming ability. FEBS J 2011; 279:126-41. [PMID: 22023160 DOI: 10.1111/j.1742-4658.2011.08405.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Listeriolysin O (LLO) is the major factor implicated in the escape of Listeria monocytogenes from the phagolysosome. It is the only representative of cholesterol-dependent cytolysins that exhibits pH-dependent activity. Despite intense studies of LLO pH-dependence, this feature of the toxin still remains incompletely explained. Here we used fluorescence and CD spectroscopy to show that the structure of LLO is not detectably affected by pH at room temperature. We observed slightly altered haemolytic and permeabilizing activities at different pH values, which we relate to reduced binding of LLO to the lipid membranes. However, alkaline pH and elevated temperatures caused rapid denaturation of LLO. Aggregates of the toxin were able to bind Congo red and Thioflavin T dyes and were visible under transmission electron microscopy as large, amorphous, micrometer-sized assemblies. The aggregates had the biophysical properties of amyloid. Analytical ultracentrifugation indicated dimerization of the protein in acidic conditions, which protects the protein against premature denaturation in the phagolysosome, where toxin activity takes place. We therefore suggest that LLO spontaneously aggregates at the neutral pH found in the host cell cytosol and that this is a major mechanism of LLO inactivation.
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Affiliation(s)
- Andrej Bavdek
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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24
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Valle A, López-Castilla A, Pedrera L, Martínez D, Tejuca M, Campos J, Fando R, Lissi E, Álvarez C, Lanio M, Pazos F, Schreier S. Cys mutants in functional regions of Sticholysin I clarify the participation of these residues in pore formation. Toxicon 2011; 58:8-17. [DOI: 10.1016/j.toxicon.2011.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 04/01/2011] [Accepted: 04/05/2011] [Indexed: 10/18/2022]
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25
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Structural insights into the oligomerization and architecture of eukaryotic membrane pore-forming toxins. Structure 2011; 19:181-91. [PMID: 21300287 DOI: 10.1016/j.str.2010.11.013] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 11/01/2010] [Accepted: 11/06/2010] [Indexed: 01/27/2023]
Abstract
Pore-forming toxins (PFTs) are proteins that are secreted as soluble molecules and are inserted into membranes to form oligomeric transmembrane pores. In this paper, we report the crystal structure of Fragaceatoxin C (FraC), a PFT isolated from the sea anemone Actinia fragacea, at 1.8 Å resolution. It consists of a crown-shaped nonamer with an external diameter of about 11.0 nm and an internal diameter of approximately 5.0 nm. Cryoelectron microscopy studies of FraC in lipid bilayers reveal the pore structure that traverses the membrane. The shape and dimensions of the crystallographic oligomer are fully consistent with the membrane pore. The FraC structure provides insight into the interactions governing the assembly process and suggests the structural changes that allow for membrane insertion. We propose a nonameric pore model that spans the membrane by forming a lipid-free α-helical bundle pore.
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26
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García-Ortega L, Alegre-Cebollada J, García-Linares S, Bruix M, Martínez-Del-Pozo A, Gavilanes JG. The behavior of sea anemone actinoporins at the water-membrane interface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2275-88. [PMID: 21621507 DOI: 10.1016/j.bbamem.2011.05.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/10/2011] [Accepted: 05/11/2011] [Indexed: 01/13/2023]
Abstract
Actinoporins constitute a group of small and basic α-pore forming toxins produced by sea anemones. They display high sequence identity and appear as multigene families. They show a singular behaviour at the water-membrane interface: In aqueous solution, actinoporins remain stably folded but, upon interaction with lipid bilayers, become integral membrane structures. These membranes contain sphingomyelin, display phase coexistence, or both. The water soluble structures of the actinoporins equinatoxin II (EqtII) and sticholysin II (StnII) are known in detail. The crystalline structure of a fragaceatoxin C (FraC) nonamer has been also determined. The three proteins fold as a β-sandwich motif flanked by two α-helices, one of them at the N-terminal end. Four regions seem to be especially important: A cluster of aromatic residues, a phosphocholine binding site, an array of basic amino acids, and the N-terminal α-helix. Initial binding of the soluble monomers to the membrane is accomplished by the cluster of aromatic amino acids, the array of basic residues, and the phosphocholine binding site. Then, the N-terminal α-helix detaches from the β-sandwich, extends, and lies parallel to the membrane. Simultaneously, oligomerization occurs. Finally, the extended N-terminal α-helix penetrates the membrane to build a toroidal pore. This model has been however recently challenged by the cryo-EM reconstruction of FraC bound to phospholipid vesicles. Actinoporins structural fold appears across all eukaryotic kingdoms in other functionally unrelated proteins. Many of these proteins neither bind to lipid membranes nor induce cell lysis. Finally, studies focusing on the therapeutic potential of actinoporins also abound.
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Affiliation(s)
- Lucía García-Ortega
- Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain
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27
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Pardo-Cea MA, Castrillo I, Alegre-Cebollada J, Martínez-del-Pozo Á, Gavilanes JG, Bruix M. Intrinsic local disorder and a network of charge-charge interactions are key to actinoporin membrane disruption and cytotoxicity. FEBS J 2011; 278:2080-9. [DOI: 10.1111/j.1742-4658.2011.08123.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Butala M, Klose D, Hodnik V, Rems A, Podlesek Z, Klare JP, Anderluh G, Busby SJW, Steinhoff HJ, Zgur-Bertok D. Interconversion between bound and free conformations of LexA orchestrates the bacterial SOS response. Nucleic Acids Res 2011; 39:6546-57. [PMID: 21576225 PMCID: PMC3159453 DOI: 10.1093/nar/gkr265] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The bacterial SOS response is essential for the maintenance of genomes, and also modulates antibiotic resistance and controls multidrug tolerance in subpopulations of cells known as persisters. In Escherichia coli, the SOS system is controlled by the interplay of the dimeric LexA transcriptional repressor with an inducer, the active RecA filament, which forms at sites of DNA damage and activates LexA for self-cleavage. Our aim was to understand how RecA filament formation at any chromosomal location can induce the SOS system, which could explain the mechanism for precise timing of induction of SOS genes. Here, we show that stimulated self-cleavage of the LexA repressor is prevented by binding to specific DNA operator targets. Distance measurements using pulse electron paramagnetic resonance spectroscopy reveal that in unbound LexA, the DNA-binding domains sample different conformations. One of these conformations is captured when LexA is bound to operator targets and this precludes interaction by RecA. Hence, the conformational flexibility of unbound LexA is the key element in establishing a co-ordinated SOS response. We show that, while LexA exhibits diverse dissociation rates from operators, it interacts extremely rapidly with DNA target sites. Modulation of LexA activity changes the occurrence of persister cells in bacterial populations.
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Affiliation(s)
- Matej Butala
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia.
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29
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Actinoporins from the sea anemones, tropical Radianthus macrodactylus and northern Oulactis orientalis: Comparative analysis of structure–function relationships. Toxicon 2010; 56:1299-314. [DOI: 10.1016/j.toxicon.2010.07.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 07/16/2010] [Accepted: 07/19/2010] [Indexed: 11/24/2022]
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30
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Bakrac B, Kladnik A, Macek P, McHaffie G, Werner A, Lakey JH, Anderluh G. A toxin-based probe reveals cytoplasmic exposure of Golgi sphingomyelin. J Biol Chem 2010; 285:22186-95. [PMID: 20463009 DOI: 10.1074/jbc.m110.105122] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Although sphingomyelin is an important cellular lipid, its subcellular distribution is not precisely known. Here we use a sea anemone cytolysin, equinatoxin II (EqtII), which specifically binds sphingomyelin, as a new marker to detect cellular sphingomyelin. A purified fusion protein composed of EqtII and green fluorescent protein (EqtII-GFP) binds to the SM rich apical membrane of Madin-Darby canine kidney (MDCK) II cells when added exogenously, but not to the SM-free basolateral membrane. When expressed intracellularly within MDCK II cells, EqtII-GFP colocalizes with markers for Golgi apparatus and not with those for nucleus, mitochondria, endoplasmic reticulum or plasma membrane. Colocalization with the Golgi apparatus was confirmed by also using NIH 3T3 fibroblasts. Moreover, EqtII-GFP was enriched in cis-Golgi compartments isolated by gradient ultracentrifugation. The data reveal that EqtII-GFP is a sensitive probe for membrane sphingomyelin, which provides new information on cytosolic exposure, essential to understand its diverse physiological roles.
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Affiliation(s)
- Biserka Bakrac
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna Pot 111, 1000 Ljubljana, Slovenia
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Bakrač B, Anderluh G. Molecular Mechanism of Sphingomyelin-Specific Membrane Binding and Pore Formation by Actinoporins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010. [DOI: 10.1007/978-1-4419-6327-7_9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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32
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Mechaly AE, Bellomio A, Morante K, González-Mañas JM, Guérin DMA. Crystallization and preliminary crystallographic analysis of fragaceatoxin C, a pore-forming toxin from the sea anemone Actinia fragacea. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:357-60. [PMID: 19342779 PMCID: PMC2664759 DOI: 10.1107/s1744309109007064] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 02/25/2009] [Indexed: 11/10/2022]
Abstract
Sea anemones produce water-soluble toxins that have the ability to interact with cell membranes and form pores within them. The mechanism of pore formation is based on an initial binding step followed by oligomerization and membrane insertion. Although the final structure of the pore remains unclear, biochemical studies indicate that it consists of a tetramer with a functional radius of approximately 1.1 nm. Since four monomers seem to be insufficient to build a pore of this size, the currently accepted model suggests that lipids might also participate in its structure. In this work, the crystallization and preliminary crystallographic analysis of two crystal forms of fragaceatoxin C (FraC), a newly characterized actinoporin from Actinia fragacea, are described. The crystals diffracted up to 1.8 A resolution and the preliminary molecular-replacement solution supports an oligomeric structure of about 120 A in diameter.
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Affiliation(s)
- A. E. Mechaly
- Unidad de Biofísica (CSIC–UPV/EHU), PO Box 644, E-48080 Bilbao, Spain
| | - A. Bellomio
- Departamento de Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas, 4000 Tucumán, Argentina
| | - K. Morante
- Unidad de Biofísica (CSIC–UPV/EHU), PO Box 644, E-48080 Bilbao, Spain
| | - J. M. González-Mañas
- Unidad de Biofísica (CSIC–UPV/EHU), PO Box 644, E-48080 Bilbao, Spain
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencia y Tecnología, Universidad del País Vasco, PO Box 644, E-48080 Bilbao, Spain
| | - D. M. A. Guérin
- Unidad de Biofísica (CSIC–UPV/EHU), PO Box 644, E-48080 Bilbao, Spain
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencia y Tecnología, Universidad del País Vasco, PO Box 644, E-48080 Bilbao, Spain
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Kristan KC, Viero G, Dalla Serra M, Macek P, Anderluh G. Molecular mechanism of pore formation by actinoporins. Toxicon 2009; 54:1125-34. [PMID: 19268680 DOI: 10.1016/j.toxicon.2009.02.026] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Actinoporins are effective pore-forming toxins produced by sea anemones. These extremely potent, basic 20 kDa proteins readily form pores in membranes that contain sphingomyelin. Much has been learned about the molecular basis of their pore-forming mechanism in recent years. Pore formation is a multi-step process that involves recognition of membrane sphingomyelin, firm binding to the membrane accompanied by the transfer of the N-terminal region to the lipid-water interface and finally pore formation after oligomerisation of three to four monomers. The final conductive pathway is formed by amphipathic alpha-helices, hence actinoporins are an important example of so-called alpha-helical pore-forming toxins. Actinoporins have become useful model proteins to study protein-membrane interactions, specific recognition of lipids in the membrane, and protein oligomerisation in the lipid milieu. Recent sequence and structural data of proteins similar to actinoporins indicate that they are not a unique family restricted to sea anemones as was long believed. An AF domain superfamily (abbreviated from actinoporin-like proteins and fungal fruit-body lectins) was defined and shown to contain members from three animal and two plant phyla. On the basis of functional properties of some members we hypothesise that AF domain proteins are peripheral membrane proteins. Finally, ability of actinoporins to form transmembrane pores has been exploited in some novel biomedical applications.
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Affiliation(s)
- Katarina Crnigoj Kristan
- Department of Biology, Biotechnical faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia
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Tejuca M, Anderluh G, Dalla Serra M. Sea anemone cytolysins as toxic components of immunotoxins. Toxicon 2009; 54:1206-14. [PMID: 19268683 DOI: 10.1016/j.toxicon.2009.02.025] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The use of membrane active toxins as toxic moieties in the construction of immunotoxins (ITs) is an attractive alternative to overcome some of the problems of classical ITs since these new conjugates are based in the use of a different mechanism of killing undesired cells. Pore-forming cytolysins from sea anemones were used in the construction of ITs targeted to different cell types including tumour cell lines and the parasite Giardia duodenalis. The results obtained support the feasibility of directing these cytolysins to the surface of the cancer cells or the parasite through their conjugation to monoclonal antibodies recognizing tumour-associated or parasite antigens, respectively. However the main problem with the IT constructed in this fashion is the lack of specificity associated with the toxin moiety. An approach designed to overcome this limitation was the construction of inactive cytolysin with built-in biological "trigger" that renders the toxin active in the presence of tumour-specific proteinases. This construction is considered as a proof of concept to demonstrate the feasibility of such activation systems in the construction of ITs based on pore-forming cytolysins from sea anemones with reduced unspecific activity. The future prospects of the use of the N-terminal region of actinoporins for construction of IT is also described.
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Affiliation(s)
- Mayra Tejuca
- Centro de Estudios de Proteínas y Departamento de Bioquímica, Facultad de Biologia, Universidad de La Habana, Calle 25 #455 e/ J e I, Vedado, Ciudad de La Habana, Cuba.
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Bakrač B, Gutiérrez-Aguirre I, Podlesek Z, Sonnen AFP, Gilbert RJ, Maček P, Lakey JH, Anderluh G. Molecular Determinants of Sphingomyelin Specificity of a Eukaryotic Pore-forming Toxin. J Biol Chem 2008; 283:18665-77. [DOI: 10.1074/jbc.m708747200] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Equinatoxin II permeabilizing activity depends on the presence of sphingomyelin and lipid phase coexistence. Biophys J 2008; 95:691-8. [PMID: 18390598 DOI: 10.1529/biophysj.108.129981] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Equinatoxin II is a pore-forming protein of the actinoporin family. After membrane binding, it inserts its N-terminal alpha-helix and forms a protein/lipid pore. Equinatoxin II activity depends on the presence of sphingomyelin in the target membrane; however, the role of this specificity is unknown. On the other hand, sphingomyelin is considered an essential ingredient of lipid rafts and promotes liquid-ordered/liquid-disordered phase separation in model membranes that mimic raft composition. Here, we used giant unilamellar vesicles to simultaneously investigate the effect of sphingomyelin and phase separation on the membrane binding and permeabilizing activity of Equinatoxin II. Our results show that Equinatoxin II binds preferentially to the liquid-ordered phase over the liquid-disordered one and that it tends to concentrate at domain interfaces. In addition, sphingomyelin strongly enhances membrane binding of the toxin but is not sufficient for membrane permeabilization. Under the same experimental conditions, Equinatoxin II formed pores in giant unilamellar vesicles containing sphingomyelin only when liquid-ordered and -disordered phases coexisted. Our observations demonstrate the importance of phase boundaries for Equinatoxin II activity and suggest a double role of sphingomyelin as a specific receptor for the toxin and as a promoter of the membrane organization necessary for Equinatoxin II action.
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Iacovache I, van der Goot FG, Pernot L. Pore formation: an ancient yet complex form of attack. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1611-23. [PMID: 18298943 DOI: 10.1016/j.bbamem.2008.01.026] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/03/2008] [Accepted: 01/04/2008] [Indexed: 02/07/2023]
Abstract
Bacteria, as well as higher organisms such as sea anemones or earthworms, have developed sophisticated virulence factors such as the pore-forming toxins (PFTs) to mount their attack against the host. One of the most fascinating aspects of PFTs is that they can adopt a water-soluble form at the beginning of their lifetime and become an integral transmembrane protein in the membrane of the target cells. There is a growing understanding of the sequence of events and the various conformational changes undergone by these toxins in order to bind to the host cell surface, to penetrate the cell membranes and to achieve pore formation. These points will be addressed in this review.
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Affiliation(s)
- Ioan Iacovache
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Faculty of Life Sciences, Station 15, Lausanne, Switzerland
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Cilli EM, Pigossi FT, Crusca E, Ros U, Martinez D, Lanio ME, Alvarez C, Schreier S. Correlations between differences in amino-terminal sequences and different hemolytic activity of sticholysins. Toxicon 2007; 50:1201-4. [PMID: 17826814 DOI: 10.1016/j.toxicon.2007.07.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 07/24/2007] [Accepted: 07/25/2007] [Indexed: 10/23/2022]
Abstract
Sticholysins I and II (St I and St II) are cytolysins produced by the sea anemone Stichodactyla helianthus. In spite of their 93% sequence homology, St II is more hemolytic against human erythrocytes than St I. In order to establish the possible causes of this difference, we studied the hemolytic activity of synthetic peptides containing sequences from the N-termini of both proteins. The results demonstrated that the differences in hemolytic activity of the toxins could be ascribed at least partly to differences in their N-termini.
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Affiliation(s)
- Eduardo M Cilli
- Department of Biochemistry and Technological Chemistry, Institute of Chemistry, UNESP--São Paulo State University, SP, Brazil
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