1
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Sea Anemones, Actinoporins, and Cholesterol. Int J Mol Sci 2022; 23:ijms23158771. [PMID: 35955905 PMCID: PMC9369217 DOI: 10.3390/ijms23158771] [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: 07/11/2022] [Revised: 08/01/2022] [Accepted: 08/05/2022] [Indexed: 11/17/2022] Open
Abstract
Spanish or Spanish-speaking scientists represent a remarkably populated group within the scientific community studying pore-forming proteins. Some of these scientists, ourselves included, focus on the study of actinoporins, a fascinating group of metamorphic pore-forming proteins produced within the venom of several sea anemones. These toxic proteins can spontaneously transit from a water-soluble fold to an integral membrane ensemble because they specifically recognize sphingomyelin in the membrane. Once they bind to the bilayer, they subsequently oligomerize into a pore that triggers cell-death by osmotic shock. In addition to sphingomyelin, some actinoporins are especially sensible to some other membrane components such as cholesterol. Our group from Universidad Complutense of Madrid has focused greatly on the role played by sterols in this water–membrane transition, a question which still remains only partially solved and constitutes the main core of the article below.
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García‐Linares S, Amigot‐Sánchez R, García‐Montoya C, Heras‐Márquez D, Alfonso C, Luque‐Ortega JR, Gavilanes JG, Martínez‐del‐Pozo Á, Palacios‐Ortega J. Sticholysin I‐II oligomerization in the absence of membranes. FEBS Lett 2022; 596:1029-1036. [DOI: 10.1002/1873-3468.14326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/17/2022] [Accepted: 02/24/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Sara García‐Linares
- Departamento de Bioquímica y Biología Molecular Universidad Complutense Madrid Spain
| | - Rafael Amigot‐Sánchez
- Departamento de Bioquímica y Biología Molecular Universidad Complutense Madrid Spain
| | - Carmen García‐Montoya
- Departamento de Bioquímica y Biología Molecular Universidad Complutense Madrid Spain
| | - Diego Heras‐Márquez
- Departamento de Bioquímica y Biología Molecular Universidad Complutense Madrid Spain
| | - Carlos Alfonso
- Systems Biochemistry of Bacterial Division Lab Centro de Investigaciones Biológicas Margarita Salas (CSIC) C. Ramiro de Maeztu 9 28040 Madrid Spain
| | - Juan Román Luque‐Ortega
- Molecular Interactions Facility Centro de Investigaciones Biológicas Margarita Salas (CSIC) C. Ramiro de Maeztu 9 28040 Madrid Spain
| | - José G. Gavilanes
- Departamento de Bioquímica y Biología Molecular Universidad Complutense Madrid Spain
| | | | - Juan Palacios‐Ortega
- Departamento de Bioquímica y Biología Molecular Universidad Complutense Madrid Spain
- Faculty of Science and Engineering Åbo Akademi University Turku Finland
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3
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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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4
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Palacios-Ortega J, Rivera-de-Torre E, García-Linares S, Gavilanes JG, Martínez-Del-Pozo Á, Slotte JP. Oligomerization of Sticholysins from Förster Resonance Energy Transfer. Biochemistry 2021; 60:314-323. [PMID: 33445865 PMCID: PMC8023573 DOI: 10.1021/acs.biochem.0c00840] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
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Sticholysins
are pore-forming toxins produced by sea anemones that
are members of the actinoporin family. They exert their activity by
forming pores on membranes, provided they have sphingomyelin. To assemble
into pores, specific recognition, binding, and oligomerization are
required. While recognition and binding have been extensively studied,
delving into the oligomerization process and the stoichiometry of
the pores has been more difficult. Here, we present evidence that
these toxins are capable of oligomerizing in solution and suggesting
that the interaction of sticholysin II (StnII) with its isoform sticholysin
I (StnI) is stronger than that of StnI with itself. We also show that
the stoichiometry of the final, thermodynamically stable StnI pores
is, at least, heptameric. Furthermore, our results indicate that this
association maintains its oligomerization number when StnII is included,
indicating that the stoichiometry of StnII is also of that order,
and not tetrameric, as previously thought. These results are compatible
with the stoichiometry observed for the crystallized pore of FraC,
another very similar actinoporin produced by a different sea anemone
species. Our results also indicate that the stoichiometry of actinoporin
pores in equilibrium is conserved regardless of the particular composition
of a given pore ensemble, which we have shown for mixed sticholysin
pores.
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Affiliation(s)
- Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, 28040 Madrid, Spain.,Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | | | - Sara García-Linares
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, 28040 Madrid, Spain
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense, 28040 Madrid, Spain
| | | | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
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Palacios-Ortega J, Rivera-de-Torre E, Gavilanes JG, Slotte JP, Martínez-Del-Pozo Á, García-Linares S. Biophysical approaches to study actinoporin-lipid interactions. Methods Enzymol 2021; 649:307-339. [PMID: 33712191 DOI: 10.1016/bs.mie.2020.12.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein-lipid interactions are crucial events from a biochemical point of view, like the interaction of proteins with the cell plasma membrane, and their study is of great importance. Actinoporins are a very powerful tool to study this kind of interactions, since they are soluble proteins in an aqueous environment, capable of inserting into membranes when they have the adequate composition. In fact, actinoporins have been used to study protein-lipid interactions for many years now. Sometimes it is not possible to use real biological membranes in the experiments, so model membranes need to be used. This article aims to give a thorough description of many of the techniques used to study actinoporin-lipid interactions, using both biological and model membranes: Hemolysis, release of vesicles content, surface plasmon resonance, isothermal titration calorimetry, fluorescence-based measurements, etc. Some of these techniques measure the actinoporins activity and some measure their binding properties. The combination of all the techniques described can offer valuable information about the thermodynamics and the kinetics of the actinoporin-lipid interaction.
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Affiliation(s)
- Juan Palacios-Ortega
- Department of Biochemistry and Molecular Biology, Complutense University, Madrid, Spain; Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Esperanza Rivera-de-Torre
- Department of Biochemistry and Molecular Biology, Complutense University, Madrid, Spain; Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - José G Gavilanes
- Department of Biochemistry and Molecular Biology, Complutense University, Madrid, Spain
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | | | - Sara García-Linares
- Department of Biochemistry and Molecular Biology, Complutense University, Madrid, Spain.
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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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Evaluation of different approaches used to study membrane permeabilization by actinoporins on model lipid vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183311. [DOI: 10.1016/j.bbamem.2020.183311] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 03/12/2020] [Accepted: 04/13/2020] [Indexed: 02/01/2023]
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8
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Rivera-de-Torre E, Palacios-Ortega J, Garb JE, Slotte JP, Gavilanes JG, Martínez-Del-Pozo Á. Structural and functional characterization of sticholysin III: A newly discovered actinoporin within the venom of the sea anemone Stichodactyla helianthus. Arch Biochem Biophys 2020; 689:108435. [PMID: 32485153 DOI: 10.1016/j.abb.2020.108435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/23/2020] [Accepted: 05/25/2020] [Indexed: 01/19/2023]
Abstract
Actinoporins are a family of pore-forming toxins produced by sea anemones as part of their venomous cocktail. These proteins remain soluble and stably folded in aqueous solution, but when interacting with sphingomyelin-containing lipid membranes, they become integral oligomeric membrane structures that form a pore permeable to cations, which leads to cell death by osmotic shock. Actinoporins appear as multigenic families within the genome of sea anemones: several genes encoding very similar actinoporins are detected within the same species. The Caribbean Sea anemone Stichodactyla helianthus produces three actinoporins (sticholysins I, II and III; StnI, StnII and StnIII) that differ in their toxic potency. For example, StnII is about four-fold more effective than StnI against sheep erythrocytes in causing hemolysis, and both show synergy. However, StnIII, recently discovered in the S. helianthus transcriptome, has not been characterized so far. Here we describe StnIII's spectroscopic and functional properties and show its potential to interact with the other Stns. StnIII seems to maintain the well-preserved fold of all actinoporins, characterized by a high content of β-sheet, but it is significantly less thermostable. Its functional characterization shows that the critical concentration needed to form active pores is higher than for either StnI or StnII, suggesting differences in behavior when oligomerizing on membrane surfaces. Our results show that StnIII is an interesting and unexpected piece in the puzzle of how this Caribbean Sea anemone species modulates its venomous activity.
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Affiliation(s)
- Esperanza Rivera-de-Torre
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain; Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland; Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA
| | - Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain; Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Jessica E Garb
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain.
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Lu A, Watkins M, Li Q, Robinson SD, Concepcion GP, Yandell M, Weng Z, Olivera BM, Safavi-Hemami H, Fedosov AE. Transcriptomic Profiling Reveals Extraordinary Diversity of Venom Peptides in Unexplored Predatory Gastropods of the Genus Clavus. Genome Biol Evol 2020; 12:684-700. [PMID: 32333764 PMCID: PMC7259678 DOI: 10.1093/gbe/evaa083] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2020] [Indexed: 12/21/2022] Open
Abstract
Predatory gastropods of the superfamily Conoidea number over 12,000 living species. The evolutionary success of this lineage can be explained by the ability of conoideans to produce complex venoms for hunting, defense, and competitive interactions. Whereas venoms of cone snails (family Conidae) have become increasingly well studied, the venoms of most other conoidean lineages remain largely uncharacterized. In the present study, we present the venom gland transcriptomes of two species of the genus Clavus that belong to the family Drilliidae. Venom gland transcriptomes of two specimens of Clavus canalicularis and two specimens of Clavus davidgilmouri were analyzed, leading to the identification of a total of 1,176 putative venom peptide toxins (drillipeptides). Based on the combined evidence of secretion signal sequence identity, entire precursor similarity search (BLAST), and the orthology inference, putative Clavus toxins were assigned to 158 different gene families. The majority of identified transcripts comprise signal, pro-, mature peptide, and post-regions, with a typically short (<50 amino acids) and cysteine-rich mature peptide region. Thus, drillipeptides are structurally similar to conotoxins. However, convincing homology with known groups of Conus toxins was only detected for very few toxin families. Among these are Clavus counterparts of Conus venom insulins (drillinsulins), porins (drilliporins), and highly diversified lectins (drillilectins). The short size of most drillipeptides and structural similarity to conotoxins were unexpected, given that most related conoidean gastropod families (Terebridae and Turridae) possess longer mature peptide regions. Our findings indicate that, similar to conotoxins, drillipeptides may represent a valuable resource for future pharmacological exploration.
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Affiliation(s)
- Aiping Lu
- Department of Central Laboratory, Shanghai Tenth People’s Hospital of Tongji University, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | | | - Qing Li
- Eccles Institute of Human Genetics, University of Utah
- High-Throughput Genomics and Bioinformatic Analysis Shared Resource, Huntsman Cancer Institute, University of Utah
| | | | - Gisela P Concepcion
- Marine Science Institute, University of the Philippines-Diliman, Quezon City, Philippines
| | - Mark Yandell
- Eccles Institute of Human Genetics, University of Utah
- Utah Center for Genetic Discovery, University of Utah
| | - Zhiping Weng
- Department of Central Laboratory, Shanghai Tenth People’s Hospital of Tongji University, School of Life Sciences and Technology, Tongji University, Shanghai, China
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School
| | | | - Helena Safavi-Hemami
- Department of Biochemistry, University of Utah
- Department of Biology, University of Copenhagen, Denmark
| | - Alexander E Fedosov
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Science, Moscow, Russia
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10
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Ramírez-Carreto S, Miranda-Zaragoza B, Rodríguez-Almazán C. Actinoporins: From the Structure and Function to the Generation of Biotechnological and Therapeutic Tools. Biomolecules 2020; 10:E539. [PMID: 32252469 PMCID: PMC7226409 DOI: 10.3390/biom10040539] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/19/2020] [Accepted: 03/21/2020] [Indexed: 12/22/2022] Open
Abstract
Actinoporins (APs) are a family of pore-forming toxins (PFTs) from sea anemones. These biomolecules exhibit the ability to exist as soluble monomers within an aqueous medium or as constitutively open oligomers in biological membranes. Through their conformational plasticity, actinoporins are considered good candidate molecules to be included for the rational design of molecular tools, such as immunotoxins directed against tumor cells and stochastic biosensors based on nanopores to analyze unique DNA or protein molecules. Additionally, the ability of these proteins to bind to sphingomyelin (SM) facilitates their use for the design of molecular probes to identify SM in the cells. The immunomodulatory activity of actinoporins in liposomal formulations for vaccine development has also been evaluated. In this review, we describe the potential of actinoporins for use in the development of molecular tools that could be used for possible medical and biotechnological applications.
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Affiliation(s)
| | | | - Claudia Rodríguez-Almazán
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Cuernavaca, Morelos 62210, Mexico; (S.R.-C.); (B.M.-Z.)
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11
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Morante K, Bellomio A, Viguera AR, González-Mañas JM, Tsumoto K, Caaveiro JMM. The Isolation of New Pore-Forming Toxins from the Sea Anemone Actinia fragacea Provides Insights into the Mechanisms of Actinoporin Evolution. Toxins (Basel) 2019; 11:toxins11070401. [PMID: 31295915 PMCID: PMC6669745 DOI: 10.3390/toxins11070401] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/29/2019] [Accepted: 07/05/2019] [Indexed: 01/23/2023] Open
Abstract
Random mutations and selective pressure drive protein adaptation to the changing demands of the environment. As a consequence, nature favors the evolution of protein diversity. A group of proteins subject to exceptional environmental stress and known for their widespread diversity are the pore-forming hemolytic proteins from sea anemones, known as actinoporins. In this study, we identified and isolated new isoforms of actinoporins from the sea anemone Actinia fragacea (fragaceatoxins). We characterized their hemolytic activity, examined their stability and structure, and performed a comparative analysis of their primary sequence. Sequence alignment reveals that most of the variability among actinoporins is associated with non-functional residues. The differences in the thermal behavior among fragaceatoxins suggest that these variability sites contribute to changes in protein stability. In addition, the protein-protein interaction region showed a very high degree of identity (92%) within fragaceatoxins, but only 25% among all actinoporins examined, suggesting some degree of specificity at the species level. Our findings support the mechanism of evolutionary adaptation in actinoporins and reflect common pathways conducive to protein variability.
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Affiliation(s)
- Koldo Morante
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Biochemistry and Molecular Biology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
- Instituto Biofisika (CSIC, UPV/EHU), Parque Científico de la UPV/EHU, Barrio Sarriena s/n, 48940 Leioa (Bizkaia), Spain
| | - Augusto Bellomio
- Department of Biochemistry and Molecular Biology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
- Instituto Biofisika (CSIC, UPV/EHU), Parque Científico de la UPV/EHU, Barrio Sarriena s/n, 48940 Leioa (Bizkaia), Spain
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) e Instituto de Química Biológica "Dr. Bernabé Bloj," Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, T4000 San Miguel de Tucumán, Argentina
| | - Ana Rosa Viguera
- Instituto Biofisika (CSIC, UPV/EHU), Parque Científico de la UPV/EHU, Barrio Sarriena s/n, 48940 Leioa (Bizkaia), Spain
| | - Juan Manuel González-Mañas
- Department of Biochemistry and Molecular Biology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
| | - Kouhei Tsumoto
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
- Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.
| | - Jose M M Caaveiro
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
- Department of Global Healthcare, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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12
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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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13
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Gerdol M, Cervelli M, Oliverio M, Modica MV. Piercing Fishes: Porin Expansion and Adaptation to Hematophagy in the Vampire Snail Cumia reticulata. Mol Biol Evol 2019; 35:2654-2668. [PMID: 30099551 PMCID: PMC6231492 DOI: 10.1093/molbev/msy156] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cytolytic pore-forming proteins are widespread in living organisms, being mostly involved in both sides of the host-pathogen interaction, either contributing to the innate defense or promoting infection. In venomous organisms, such as spiders, insects, scorpions, and sea anemones, pore-forming proteins are often secreted as key components of the venom. Coluporins are pore-forming proteins recently discovered in the Mediterranean hematophagous snail Cumia reticulata (Colubrariidae), highly expressed in the salivary glands that discharge their secretion at close contact with the host. To understand their putative functional role, we investigated coluporins' molecular diversity and evolutionary patterns. Coluporins is a well-diversified family including at least 30 proteins, with an overall low sequence similarity but sharing a remarkably conserved actinoporin-like predicted structure. Tracking the evolutionary history of the molluscan porin genes revealed a scattered distribution of this family, which is present in some other lineages of predatory gastropods, including venomous conoidean snails. Comparative transcriptomic analyses highlighted the expansion of porin genes as a lineage-specific feature of colubrariids. Coluporins seem to have evolved from a single ancestral porin gene present in the latest common ancestor of all Caenogastropoda, undergoing massive expansion and diversification in this colubrariid lineage through repeated gene duplication events paired with widespread episodic positive selection. As for other parasites, these findings are congruent with a "one-sided arms race," equipping the parasite with multiple variants in order to broaden its host spectrum. Overall, our results pinpoint a crucial adaptive role for coluporins in the evolution of the peculiar trophic ecology of vampire snails.
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Affiliation(s)
- Marco Gerdol
- Department of Life Sciences, Trieste University, Italy
| | | | - Marco Oliverio
- Department of Biology and Biotechnologies "Charles Darwin", Sapienza University, Roma, Italy
| | - Maria Vittoria Modica
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Naples, Italy.,UMR5247, University of Montpellier, France
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14
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Leychenko E, Isaeva M, Tkacheva E, Zelepuga E, Kvetkina A, Guzev K, Monastyrnaya M, Kozlovskaya E. Multigene Family of Pore-Forming Toxins from Sea Anemone Heteractis crispa. Mar Drugs 2018; 16:E183. [PMID: 29794988 PMCID: PMC6025637 DOI: 10.3390/md16060183] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/21/2018] [Accepted: 05/22/2018] [Indexed: 11/23/2022] Open
Abstract
Sea anemones produce pore-forming toxins, actinoporins, which are interesting as tools for cytoplasmic membranes study, as well as being potential therapeutic agents for cancer therapy. This investigation is devoted to structural and functional study of the Heteractis crispa actinoporins diversity. Here, we described a multigene family consisting of 47 representatives expressed in the sea anemone tentacles as prepropeptide-coding transcripts. The phylogenetic analysis revealed that actinoporin clustering is consistent with the division of sea anemones into superfamilies and families. The transcriptomes of both H. crispa and Heteractis magnifica appear to contain a large repertoire of similar genes representing a rapid expansion of the actinoporin family due to gene duplication and sequence divergence. The presence of the most abundant specific group of actinoporins in H. crispa is the major difference between these species. The functional analysis of six recombinant actinoporins revealed that H. crispa actinoporin grouping was consistent with the different hemolytic activity of their representatives. According to molecular modeling data, we assume that the direction of the N-terminal dipole moment tightly reflects the actinoporins' ability to possess hemolytic activity.
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Affiliation(s)
- Elena Leychenko
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
- School of Natural Sciences, Far Eastern Federal University, Sukhanova Street 8, Vladivostok 690091, Russia.
| | - Marina Isaeva
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
- School of Natural Sciences, Far Eastern Federal University, Sukhanova Street 8, Vladivostok 690091, Russia.
| | - Ekaterina Tkacheva
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
| | - Elena Zelepuga
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
| | - Aleksandra Kvetkina
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
| | - Konstantin Guzev
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
| | - Margarita Monastyrnaya
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
| | - Emma Kozlovskaya
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159, Pr. 100 let Vladivostoku, Vladivostok 690022, Russia.
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15
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Rivera-de-Torre E, Martínez-Del-Pozo Á, Garb JE. Stichodactyla helianthus' de novo transcriptome assembly: Discovery of a new actinoporin isoform. Toxicon 2018; 150:105-114. [PMID: 29787779 DOI: 10.1016/j.toxicon.2018.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 05/17/2018] [Accepted: 05/18/2018] [Indexed: 01/29/2023]
Abstract
Transcriptomic profiling of venom producing tissues from different animals is an effective approach for discovering new toxins useful in biotechnological and pharmaceutical applications, as well in evolutionary comparative studies of venomous animals. Stichodactyla helianthus is a Caribbean sea anemone which produces actinoporins as part of its toxic venom. This family of pore forming toxins is multigenic and at least two different isoforms, encoded by separate genes, are produced by S. helianthus. These isoforms, sticholysins I and II, share 93% amino acid identity but differ in their pore forming activity and act synergistically. This observation suggests that other actinoporin isoforms, if present in the venomous mixture, could offer an advantageous strategy to modulate whole venom activity. Using high-throughput sequencing we generated a de novo transcriptome of S. helianthus and determined the relative expression of assembled transcripts using RNA-Seq to better characterize components of this species' venom, focusing on actinoporin diversity. Applying this approach, we have discovered at least one new actinoporin variant from S. helianthus in addition to several other putative venom components.
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Affiliation(s)
- Esperanza Rivera-de-Torre
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA; Departamento de Bioquímica y Biología Molecular, Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain.
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular, Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Jessica E Garb
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA
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16
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Ben-Ari H, Paz M, Sher D. The chemical armament of reef-building corals: inter- and intra-specific variation and the identification of an unusual actinoporin in Stylophora pistilata. Sci Rep 2018; 8:251. [PMID: 29321526 PMCID: PMC5762905 DOI: 10.1038/s41598-017-18355-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 12/04/2017] [Indexed: 01/20/2023] Open
Abstract
Corals, like other cnidarians, are venomous animals that rely on stinging cells (nematocytes) and their toxins to catch prey and defend themselves against predators. However, little is known about the chemical arsenal employed by stony corals, despite their ecological importance. Here, we show large differences in the density of nematocysts and whole-body hemolytic activity between different species of reef-building corals. In the branched coral Stylophora pistillata, the tips of the branches exhibited a greater hemolytic activity than the bases. Hemolytic activity and nematocyst density were significantly lower in Stylophora that were maintained for close to a year in captivity compared to corals collected from the wild. A cysteine-containing actinoporin was identified in Stylophora following partial purification and tandem mass spectrometry. This toxin, named Δ-Pocilopotoxin-Spi1 (Δ-PCTX-Spi1) is the first hemolytic toxin to be partially isolated and characterized in true reef-building corals. Loss of hemolytic activity during chromatography suggests that this actinoporin is only one of potentially several hemolytic molecules. These results suggest that the capacity to employ offensive and defensive chemicals by corals is a dynamic trait within and between coral species, and provide a first step towards identifying the molecular components of the coral chemical armament.
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Affiliation(s)
- Hanit Ben-Ari
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.,The Interuniversity Institute for Marine Sciences, Eilat, Israel
| | - Moran Paz
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Daniel Sher
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.
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17
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Rivera-de-Torre E, Palacios-Ortega J, García-Linares S, Gavilanes JG, Martínez-Del-Pozo Á. One single salt bridge explains the different cytolytic activities shown by actinoporins sticholysin I and II from the venom of Stichodactyla helianthus. Arch Biochem Biophys 2017; 636:79-89. [PMID: 29138096 DOI: 10.1016/j.abb.2017.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/06/2017] [Accepted: 11/10/2017] [Indexed: 10/18/2022]
Abstract
Sticholysins I and II (StnI and StnII), α-pore forming toxins from the sea anemone Stichodactyla helianthus, are water-soluble toxic proteins which upon interaction with lipid membranes of specific composition bind to the bilayer, extend and insert their N-terminal α-helix, and become oligomeric integral membrane structures. The result is a pore that leads to cell death by osmotic shock. StnI and StnII show 93% of sequence identity, but also different membrane pore-forming activities. The hydrophobicity profile along the first 18 residues revealed differences which were canceled by substituting StnI amino acids 2 and 9. Accordingly, the StnID9A mutant, and the corresponding StnIE2AD9A variant, showed enhanced hemolytic activity. They also revealed a key role for an exposed salt bridge between Asp9 and Lys68. This interaction is not possible in StnII but appears conserved in the other two well-characterized actinoporins, equinatoxin II and fragaceatoxin C. The StnII mutant A8D showed that this single replacement was enough to transform StnII into a version with impaired pore-forming activity. Overall, the results show the key importance of this salt bridge linking the N-terminal stretch to the β-sandwich core. A conclusion of general application for the understanding of salt bridges role in protein design, folding and stability.
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Affiliation(s)
- Esperanza Rivera-de-Torre
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - Sara García-Linares
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain.
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular I, Facultades de Química y Biología, Universidad Complutense, 28040 Madrid, Spain.
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18
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Palacios-Ortega J, García-Linares S, Rivera-de-Torre E, Gavilanes JG, Martínez-Del-Pozo Á, Slotte JP. Differential Effect of Bilayer Thickness on Sticholysin Activity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11018-11027. [PMID: 28933861 DOI: 10.1021/acs.langmuir.7b01765] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this study, we examined the influence of bilayer thickness on the activity of the actinoporin toxins sticholysin I and II (StnI and StnII) at 25 °C. Bilayer thickness was varied using dimonounsaturated phosphatidylcholine (PC) analogues (with 14:1, 16:1, 18:1, 20:1, and 22:1 acyl chains). In addition, N-14:0-sphingomyelin (SM) was always included because StnI and StnII are SM specific. Cholesterol was also incorporated as indicated. In cholesterol-free large unilamellar vesicles (LUVs) the PC:SM molar ratio was 4:1, and when cholesterol was included, the complete molar ratio was 4:1:0.5 (PC:SM:cholesterol, respectively). Stn toxins promote bilayer leakage through pores formed by oligomerized toxin monomers. Initial calcein leakage was moderately dependent on bilayer PC acyl chain length (and thus bilayer thickness), with higher rates observed with di-16:1 and di-18:1 PC bilayers. In the presence of cholesterol, the maximum rates of calcein leakage were observed in di-14:1 and di-16:1 PC bilayers. Using isothermal titration calorimetry to study the Stn-LUV interaction, we observed that the bilayer affinity constant (Ka) peaked with LUVs containing di-18:1 PC, and was lower in shorter and longer PC acyl chain bilayers. The presence of cholesterol increased the binding affinity approximately 30-fold at the optimal bilayer thickness (di-18:1-PC). We conclude that bilayer thickness affects both functional and conformational aspects of Stn membrane binding and pore formation. Moreover, the length of the actinoporins' N-terminal α-helix, which penetrates the membrane to form a functional pore, appears to be optimal for the membrane thickness represented by di-18:1 PC.
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Affiliation(s)
- Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid 28040, Spain
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , 20500 Turku, Finland
| | - Sara García-Linares
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid 28040, Spain
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , 20500 Turku, Finland
| | | | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid 28040, Spain
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid 28040, Spain
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , 20500 Turku, Finland
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19
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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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20
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García-Linares S, Rivera-de-Torre E, Morante K, Tsumoto K, Caaveiro JMM, Gavilanes JG, Slotte JP, Martínez-Del-Pozo Á. Differential Effect of Membrane Composition on the Pore-Forming Ability of Four Different Sea Anemone Actinoporins. Biochemistry 2016; 55:6630-6641. [PMID: 27933793 DOI: 10.1021/acs.biochem.6b01007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Sea anemone actinoporins constitute a protein family of multigene pore-forming toxins (PFT). Equinatoxin II (EqtII), fragaceatoxin C (FraC), and sticholysins I and II (StnI and StnII, respectively), produced by three different sea anemone species, are the only actinoporins whose molecular structures have been studied in depth. These four proteins show high sequence identities and practically coincident three-dimensional structures. However, their pore-forming activity can be quite different depending on the model lipid system employed, a feature that has not been systematically studied before. Therefore, the aim of this work was to evaluate and compare the influence of several distinct membrane conditions on their particular pore-forming behavior. Using a complex model membrane system, such as sheep erythrocytes, StnII showed hemolytic activity much higher than those of the other three actinoporins studied. In lipid model systems, pore-forming ability when assayed against 4:1 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/sphingomyelin (SM) vesicles, with the membrane binding being the rate-limiting step, decreased in the following order: StnI > StnII > EqtII > FraC. When using 1:1:1 DOPC/SM/cholesterol LUVs, the presence of Chol not only enhanced membrane binding affinities by ∼2 orders of magnitude but also revealed how StnII was much faster than the other three actinoporins in producing calcein release. This ability agrees with the proposal that explains this behavior in terms of their high sequence variability along their first 30 N-terminal residues. The influence of interfacial hydrogen bonding in SM- or dihydro-SM-containing bilayers was also shown to be a generalized feature of the four actinoporins studied. It is finally hypothesized that this observed variable ability could be explained as a consequence of their distinct specificities and/or membrane binding affinities. Eventually, this behavior can be modulated by the nature of their natural target membranes or the interaction with not yet characterized isotoxin forms from the same sea anemone species.
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Affiliation(s)
- Sara García-Linares
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid, Spain.,Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , Turku, Finland
| | | | - Koldo Morante
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kouhei Tsumoto
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Jose M M Caaveiro
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid, Spain
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , Turku, Finland
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21
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García-Linares S, Maula T, Rivera-de-Torre E, Gavilanes JG, Slotte JP, Martínez-Del-Pozo Á. Role of the Tryptophan Residues in the Specific Interaction of the Sea Anemone Stichodactyla helianthus's Actinoporin Sticholysin II with Biological Membranes. Biochemistry 2016; 55:6406-6420. [PMID: 27933775 DOI: 10.1021/acs.biochem.6b00935] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Actinoporins are pore-forming toxins from sea anemones. Upon interaction with sphingomyelin-containing bilayers, they become integral oligomeric membrane structures that form a pore. Sticholysin II from Stichodactyla helianthus contains five tryptophans located at strategic positions; its role has now been studied using different mutants. Results show that W43 and W115 play a determinant role in maintaining the high thermostability of the protein, while W146 provides specific interactions for protomer-protomer assembly. W110 and W114 sustain the hydrophobic effect, which is one of the major driving forces for membrane binding in the presence of Chol. However, in its absence, additional interactions with sphingomyelin are required. These conclusions were confirmed with two sphingomyelin analogues, one of which had impaired hydrogen bonding properties. The results obtained support actinoporins' Trp residues playing a major role in membrane recognition and binding, but their residues have an only minor influence on the diffusion and oligomerization steps needed to assemble a functional pore.
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Affiliation(s)
- Sara García-Linares
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid, Spain.,Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , Turku, Finland
| | - Terhi Maula
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , Turku, Finland
| | | | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense , Madrid, Spain
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University , Turku, Finland
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