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Mr. Juan Palacios-Ortega
Åbo Akademi University (Turku)

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actinoporins
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Review article
Published: 08 July 2021 in Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics
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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.

ACS Style

Juan Palacios-Ortega; Sara García-Linares; Esperanza Rivera-De-Torre; Diego Heras-Márquez; José G. Gavilanes; J. Peter Slotte; Álvaro Martínez-Del-Pozo. Structural foundations of sticholysin functionality. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2021, 1869, 140696 .

AMA Style

Juan Palacios-Ortega, Sara García-Linares, Esperanza Rivera-De-Torre, Diego Heras-Márquez, José G. Gavilanes, J. Peter Slotte, Álvaro Martínez-Del-Pozo. Structural foundations of sticholysin functionality. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. 2021; 1869 (10):140696.

Chicago/Turabian Style

Juan Palacios-Ortega; Sara García-Linares; Esperanza Rivera-De-Torre; Diego Heras-Márquez; José G. Gavilanes; J. Peter Slotte; Álvaro Martínez-Del-Pozo. 2021. "Structural foundations of sticholysin functionality." Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 1869, no. 10: 140696.

Research article
Published: 14 January 2021 in Biochemistry
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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.

ACS Style

Juan Palacios-Ortega; Esperanza Rivera-De-Torre; Sara García-Linares; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. Oligomerization of Sticholysins from Förster Resonance Energy Transfer. Biochemistry 2021, 60, 314 -323.

AMA Style

Juan Palacios-Ortega, Esperanza Rivera-De-Torre, Sara García-Linares, José G. Gavilanes, Álvaro Martínez-Del-Pozo, J. Peter Slotte. Oligomerization of Sticholysins from Förster Resonance Energy Transfer. Biochemistry. 2021; 60 (4):314-323.

Chicago/Turabian Style

Juan Palacios-Ortega; Esperanza Rivera-De-Torre; Sara García-Linares; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. 2021. "Oligomerization of Sticholysins from Förster Resonance Energy Transfer." Biochemistry 60, no. 4: 314-323.

Review
Published: 24 November 2020 in International Journal of Molecular Sciences
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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.

ACS Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; J. Peter Slotte; José G. Gavilanes; Álvaro Martínez-Del-Pozo; Sara García-Linares. Functional and Structural Variation Among Sticholysins, Pore-Forming Proteins from the Sea Anemone Stichodactyla helianthus. International Journal of Molecular Sciences 2020, 21, 8915 .

AMA Style

Esperanza Rivera-De-Torre, Juan Palacios-Ortega, J. Peter Slotte, José G. Gavilanes, Álvaro Martínez-Del-Pozo, Sara García-Linares. Functional and Structural Variation Among Sticholysins, Pore-Forming Proteins from the Sea Anemone Stichodactyla helianthus. International Journal of Molecular Sciences. 2020; 21 (23):8915.

Chicago/Turabian Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; J. Peter Slotte; José G. Gavilanes; Álvaro Martínez-Del-Pozo; Sara García-Linares. 2020. "Functional and Structural Variation Among Sticholysins, Pore-Forming Proteins from the Sea Anemone Stichodactyla helianthus." International Journal of Molecular Sciences 21, no. 23: 8915.

Journal article
Published: 30 May 2020 in Archives of Biochemistry and Biophysics
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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.

ACS Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; Jessica E. Garb; J. Peter Slotte; José G. Gavilanes; Álvaro Martínez-Del-Pozo. Structural and functional characterization of sticholysin III: A newly discovered actinoporin within the venom of the sea anemone Stichodactyla helianthus. Archives of Biochemistry and Biophysics 2020, 689, 108435 .

AMA Style

Esperanza Rivera-De-Torre, Juan Palacios-Ortega, Jessica E. Garb, J. Peter Slotte, José G. Gavilanes, Álvaro Martínez-Del-Pozo. Structural and functional characterization of sticholysin III: A newly discovered actinoporin within the venom of the sea anemone Stichodactyla helianthus. Archives of Biochemistry and Biophysics. 2020; 689 ():108435.

Chicago/Turabian Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; Jessica E. Garb; J. Peter Slotte; José G. Gavilanes; Álvaro Martínez-Del-Pozo. 2020. "Structural and functional characterization of sticholysin III: A newly discovered actinoporin within the venom of the sea anemone Stichodactyla helianthus." Archives of Biochemistry and Biophysics 689, no. : 108435.

Journal article
Published: 27 April 2020 in Biochimica et Biophysica Acta (BBA) - Biomembranes
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Release of aqueous contents from model lipid vesicles has been a standard procedure to evaluate pore formation efficiency by actinoporins, such as sticholysin II (StnII), for the last few decades. However, regardless of the probe of choice, the results reported that StnII action was never able to empty the vesicles completely. This was hard to explain if StnII pores were to be stable and always leaky for the probes used. To address this question, we have used a variety of probes, including rhodamine 6G or Tb3+, to test the permeability of StnII's pores. Our results indicate that calcein was in fact too large to fit through StnII's pores, and that the standard method in the field is actually reporting StnII-induced transient permeation of the membrane rather than the passage of solutes through the stable assembled pores. In order to evaluate the permeability of these structures, we used a dithionite-based assay, which showed that the final pores were in fact open. Thus, our results indicate that the stable actinoporins' pores are open in spite of plateaued classic release curves. Besides the proper pore, the first stages of pore formation would inflict serious damage to living cells as well.

ACS Style

Juan Palacios-Ortega; Esperanza Rivera-De-Torre; José G. Gavilanes; J. Peter Slotte; Álvaro Martínez-Del-Pozo. Evaluation of different approaches used to study membrane permeabilization by actinoporins on model lipid vesicles. Biochimica et Biophysica Acta (BBA) - Biomembranes 2020, 1862, 183311 .

AMA Style

Juan Palacios-Ortega, Esperanza Rivera-De-Torre, José G. Gavilanes, J. Peter Slotte, Álvaro Martínez-Del-Pozo. Evaluation of different approaches used to study membrane permeabilization by actinoporins on model lipid vesicles. Biochimica et Biophysica Acta (BBA) - Biomembranes. 2020; 1862 (9):183311.

Chicago/Turabian Style

Juan Palacios-Ortega; Esperanza Rivera-De-Torre; José G. Gavilanes; J. Peter Slotte; Álvaro Martínez-Del-Pozo. 2020. "Evaluation of different approaches used to study membrane permeabilization by actinoporins on model lipid vesicles." Biochimica et Biophysica Acta (BBA) - Biomembranes 1862, no. 9: 183311.

Perspective
Published: 25 June 2019 in Toxins
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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.

ACS Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; José Gavilanes; Álvaro Martínez-Del-Pozo; Sara García-Linares. Pore-Forming Proteins from Cnidarians and Arachnids as Potential Biotechnological Tools. Toxins 2019, 11, 370 .

AMA Style

Esperanza Rivera-De-Torre, Juan Palacios-Ortega, José Gavilanes, Álvaro Martínez-Del-Pozo, Sara García-Linares. Pore-Forming Proteins from Cnidarians and Arachnids as Potential Biotechnological Tools. Toxins. 2019; 11 (6):370.

Chicago/Turabian Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; José Gavilanes; Álvaro Martínez-Del-Pozo; Sara García-Linares. 2019. "Pore-Forming Proteins from Cnidarians and Arachnids as Potential Biotechnological Tools." Toxins 11, no. 6: 370.

Journal article
Published: 15 May 2019 in Biophysical Journal
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Actinoporins are a group of soluble toxic proteins that bind to membranes containing sphingomyelin (SM) and oligomerize to form pores. Sticholysin II (StnII) is a member of the actinoporin family produced by Stichodactyla helianthus. Cholesterol (Chol) is known to enhance the activity of StnII. However, the molecular mechanisms behind this activation have remained obscure, although the activation is not Chol specific but rather sterol specific. To further explore how bilayer lipids affect or are affected by StnII, we have used a multiprobe approach (fluorescent analogs of both Chol and SM) in combination with a series of StnII tryptophan (Trp) mutants to study StnII/bilayer interactions. First, we compared StnII bilayer permeabilization in the presence of Chol or oleoyl-ceramide (OCer). The comparison was done because both Chol and OCer have a 1-hydroxyl, which helps to orient the molecule in the bilayer (although OCer has additional polar functional groups). Both Chol and OCer also have increased affinity for SM, which StnII may recognize. However, our results show that only Chol was able to activate StnII-induced bilayer permeabilization; OCer failed to activate it. To further examine possible Chol/StnII interactions, we measured Förster resonance energy transfer between Trp in StnII and cholestatrienol, a fluorescent analog of Chol. We could show higher Förster resonance energy transfer efficiency between cholestatrienol and Trps in position 100 and 114 of StnII when compared to three other Trp positions further away from the bilayer binding region of StnII. Taken together, our results suggest that StnII was able to attract Chol to its vicinity, maybe by showing affinity for Chol. SM interactions are known to be important for StnII binding to bilayers, and Chol is known to facilitate subsequent permeabilization of the bilayers by StnII. Our results help to better understand the role of these important membrane lipids for the bilayer properties of StnII.

ACS Style

Juan Palacios-Ortega; Sara García-Linares; Esperanza Rivera-De-Torre; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte; Esperanza Rivera-De-Torre. Sticholysin, Sphingomyelin, and Cholesterol: A Closer Look at a Tripartite Interaction. Biophysical Journal 2019, 116, 2253 -2265.

AMA Style

Juan Palacios-Ortega, Sara García-Linares, Esperanza Rivera-De-Torre, José G. Gavilanes, Álvaro Martínez-Del-Pozo, J. Peter Slotte, Esperanza Rivera-De-Torre. Sticholysin, Sphingomyelin, and Cholesterol: A Closer Look at a Tripartite Interaction. Biophysical Journal. 2019; 116 (12):2253-2265.

Chicago/Turabian Style

Juan Palacios-Ortega; Sara García-Linares; Esperanza Rivera-De-Torre; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte; Esperanza Rivera-De-Torre. 2019. "Sticholysin, Sphingomyelin, and Cholesterol: A Closer Look at a Tripartite Interaction." Biophysical Journal 116, no. 12: 2253-2265.

Journal article
Published: 01 March 2019 in Biophysical Journal
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The mode of interactions between palmitoyl lysophosphatidylcholine (palmitoyl lyso-PC) or other lysophospholipids (lyso-PLs) and palmitoyl ceramide (PCer) or other ceramide analogs in dioleoylphosphatidylcholine (DOPC) bilayers has been examined. PCer is known to segregate laterally into a ceramide-rich phase at concentrations that depend on the nature of the ceramides and the co-phospholipids. In DOPC bilayers, PCer forms a ceramide-rich phase at concentrations above 10 mol%. In the presence of 20 mol% palmitoyl lyso-PC in the DOPC bilayer, the lateral segregation of PCer was markedly facilitated (segregation at lower PCer concentrations). The thermostability of the PCer-rich phase in the presence of palmitoyl lyso-PC was also increased compared to that in the absence of palmitoyl lyso-PC. Other saturated lyso-PLs (e.g., palmitoyl lyso-phosphatidylethanolamine and lyso-sphingomyelin) also facilitated the lateral segregation of PCer in a similar manner as palmitoyl lyso-PC. When examined in the DOPC bilayer, it appeared that the association between palmitoyl lyso-PC and PCer was equimolar in nature. It is proposed that the interaction of PCer with lyso-PLs was driven by the need of ceramide to obtain a large-headgroup co-lipid, and saturated lyso-PLs were preferred co-lipids over DOPC because of the nature of their acyl chain. Structural analogs of PCer (1- or 3-deoxy-PCer) were also associated with palmitoyl lyso-PC, similarly to PCer, suggesting that the ceramide/lyso-PL interaction was not sensitive to structural alterations in the ceramide molecule. Binary complexes containing palmitoyl lyso-PC and ceramide were prepared, and these had a bilayer structure as ascertained by transmission electron microscopy. It is concluded that ceramides and lyso-PLs associated with each other both in binary bilayers and in ternary systems based on the DOPC bilayers. This association may have biological relevance under conditions in which both sphingomyelinases and phospholipase A2 enzymes are activated, such as during inflammatory processes.

ACS Style

Abdullah Al Sazzad; Anna Möuts; Juan Palacios-Ortega; Kai-Lan Lin; Thomas K.M. Nyholm; J. Peter Slotte. Natural Ceramides and Lysophospholipids Cosegregate in Fluid Phosphatidylcholine Bilayers. Biophysical Journal 2019, 116, 1105 -1114.

AMA Style

Abdullah Al Sazzad, Anna Möuts, Juan Palacios-Ortega, Kai-Lan Lin, Thomas K.M. Nyholm, J. Peter Slotte. Natural Ceramides and Lysophospholipids Cosegregate in Fluid Phosphatidylcholine Bilayers. Biophysical Journal. 2019; 116 (6):1105-1114.

Chicago/Turabian Style

Abdullah Al Sazzad; Anna Möuts; Juan Palacios-Ortega; Kai-Lan Lin; Thomas K.M. Nyholm; J. Peter Slotte. 2019. "Natural Ceramides and Lysophospholipids Cosegregate in Fluid Phosphatidylcholine Bilayers." Biophysical Journal 116, no. 6: 1105-1114.

Reference entry
Published: 16 February 2018 in eLS
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Fungal ribotoxins constitute a family of extracellular ribonucleases with exquisite specificity against rRNA (ribonucleic acid). They induce apoptotic death of cells after inhibiting protein translation. Ribosomes become functionally incompetent because ribotoxins cleave one single phosphodiester bond, located at a unique and universally conserved loop, needed for elongation factors function. As secreted proteins, ribotoxins need to cross the membrane of their target cells in order to exert their catalytic activity, and they do it without receptor mediation. Using lipid model systems, it has been shown that they are able to enter cells with membranes enriched in acidic phospholipids. Both membrane-interacting and ribosomal-recognition activities are characterised by distinct structural features. Even though the natural function of ribotoxins is not known yet, their production by entomopathogenic fungi has suggested their insecticidal role. After decades of detailed study, the biotechnological potential of ribotoxins in pest control and as antitumour agents is becoming evident.

ACS Style

Lucía García-Ortega; Juan Palacios-Ortega; Alvaro Martinez-Del-Pozo. Fungal Ribotoxins. eLS 2018, 1 -9.

AMA Style

Lucía García-Ortega, Juan Palacios-Ortega, Alvaro Martinez-Del-Pozo. Fungal Ribotoxins. eLS. 2018; ():1-9.

Chicago/Turabian Style

Lucía García-Ortega; Juan Palacios-Ortega; Alvaro Martinez-Del-Pozo. 2018. "Fungal Ribotoxins." eLS , no. : 1-9.

Journal article
Published: 01 December 2017 in Archives of Biochemistry and Biophysics
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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.

ACS Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; Sara García-Linares; José G. Gavilanes; Álvaro Martínez-Del-Pozo. One single salt bridge explains the different cytolytic activities shown by actinoporins sticholysin I and II from the venom of Stichodactyla helianthus. Archives of Biochemistry and Biophysics 2017, 636, 79 -89.

AMA Style

Esperanza Rivera-De-Torre, Juan Palacios-Ortega, Sara García-Linares, José G. Gavilanes, Álvaro Martínez-Del-Pozo. One single salt bridge explains the different cytolytic activities shown by actinoporins sticholysin I and II from the venom of Stichodactyla helianthus. Archives of Biochemistry and Biophysics. 2017; 636 ():79-89.

Chicago/Turabian Style

Esperanza Rivera-De-Torre; Juan Palacios-Ortega; Sara García-Linares; José G. Gavilanes; Álvaro Martínez-Del-Pozo. 2017. "One single salt bridge explains the different cytolytic activities shown by actinoporins sticholysin I and II from the venom of Stichodactyla helianthus." Archives of Biochemistry and Biophysics 636, no. : 79-89.

Research article
Published: 04 October 2017 in Langmuir
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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 di-monounsaturated phosphatidylcholine (PC) analogs (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 (LUV) 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.

ACS Style

Juan Palacios-Ortega; Sara García-Linares; Esperanza Rivera-De-Torre; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. Differential Effect of Bilayer Thickness on Sticholysin Activity. Langmuir 2017, 33, 11018 -11027.

AMA Style

Juan Palacios-Ortega, Sara García-Linares, Esperanza Rivera-De-Torre, José G. Gavilanes, Álvaro Martínez-Del-Pozo, J. Peter Slotte. Differential Effect of Bilayer Thickness on Sticholysin Activity. Langmuir. 2017; 33 (41):11018-11027.

Chicago/Turabian Style

Juan Palacios-Ortega; Sara García-Linares; Esperanza Rivera-De-Torre; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. 2017. "Differential Effect of Bilayer Thickness on Sticholysin Activity." Langmuir 33, no. 41: 11018-11027.

Book chapter
Published: 01 January 2017 in Advances in Biomembranes and Lipid Self-Assembly
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ACS Style

Sara García-Linares; Esperanza Rivera-De-Torre; Juan Palacios-Ortega; José G. Gavilanes; Álvaro Martínez-Del-Pozo. The Metamorphic Transformation of a Water-Soluble Monomeric Protein Into an Oligomeric Transmembrane Pore. Advances in Biomembranes and Lipid Self-Assembly 2017, 51 -97.

AMA Style

Sara García-Linares, Esperanza Rivera-De-Torre, Juan Palacios-Ortega, José G. Gavilanes, Álvaro Martínez-Del-Pozo. The Metamorphic Transformation of a Water-Soluble Monomeric Protein Into an Oligomeric Transmembrane Pore. Advances in Biomembranes and Lipid Self-Assembly. 2017; ():51-97.

Chicago/Turabian Style

Sara García-Linares; Esperanza Rivera-De-Torre; Juan Palacios-Ortega; José G. Gavilanes; Álvaro Martínez-Del-Pozo. 2017. "The Metamorphic Transformation of a Water-Soluble Monomeric Protein Into an Oligomeric Transmembrane Pore." Advances in Biomembranes and Lipid Self-Assembly , no. : 51-97.

Journal article
Published: 01 June 2016 in Biochimica et Biophysica Acta (BBA) - Biomembranes
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Highlights•Sphingomyelin and dihydro sphingomyelin hydrogen bond differently•Sticholysin binds to sphingomyelin and forms pores in fluid bilayers•Sticholysin failed to form pores in fluid dihydro sphingomyelin bilayers•Strong intermolecular hydrogen bonding appeared to hinder pore formation AbstractSticholysin I and II (StnI and StnII) are pore-forming toxins that use sphingomyelin (SM) for membrane binding. We examined how hydrogen bonding among membrane SMs affected the StnI- and StnII-induced pore formation process, resulting in bilayer permeabilization. We compared toxin-induced permeabilization in bilayers containing either SM or dihydro-SM (lacking the trans Δ4 double bond of the long-chain base), since their hydrogen-bonding properties are known to differ greatly. We observed that whereas both StnI and StnII formed pores in unilamellar vesicles containing palmitoyl-SM or oleoyl-SM, the toxins failed to similarly form pores in vesicles prepared from dihydro-PSM or dihydro-OSM. In supported bilayers containing OSM, StnII bound efficiently, as determined by surface plasmon resonance. However, StnII binding to supported bilayers prepared from dihydro-OSM was very low under similar experimental conditions. The association of the positively charged StnII (at pH 7.0) with unilamellar vesicles prepared from OSM led to a concentration-dependent increase in vesicle charge, as determined from zeta-potential measurements. With dihydro-OSM vesicles, a similar response was not observed. Benzyl alcohol, which is a small hydrogen-bonding compound with affinity to lipid bilayer interfaces, strongly facilitated StnII-induced pore formation in dihydro-OSM bilayers, suggesting that hydrogen bonding in the interfacial region originally prevented StnII from membrane binding and pore formation. We conclude that interfacial hydrogen bonding was able to affect the membrane association of StnI- and StnII, and hence their pore forming capacity. Our results suggest that other types of protein interactions in bilayers may also be affected by hydrogen-bonding origination from SMs. Graphical abstractInhibitory effects of sphingomyelin hydrogen bonding on sticholysin-induced pore formation

ACS Style

Sara García-Linares; Juan Palacios-Ortega; Tomokazu Yasuda; Mia Åstrand; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. Toxin-induced pore formation is hindered by intermolecular hydrogen bonding in sphingomyelin bilayers. Biochimica et Biophysica Acta (BBA) - Biomembranes 2016, 1858, 1189 -1195.

AMA Style

Sara García-Linares, Juan Palacios-Ortega, Tomokazu Yasuda, Mia Åstrand, José G. Gavilanes, Álvaro Martínez-Del-Pozo, J. Peter Slotte. Toxin-induced pore formation is hindered by intermolecular hydrogen bonding in sphingomyelin bilayers. Biochimica et Biophysica Acta (BBA) - Biomembranes. 2016; 1858 (6):1189-1195.

Chicago/Turabian Style

Sara García-Linares; Juan Palacios-Ortega; Tomokazu Yasuda; Mia Åstrand; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. 2016. "Toxin-induced pore formation is hindered by intermolecular hydrogen bonding in sphingomyelin bilayers." Biochimica et Biophysica Acta (BBA) - Biomembranes 1858, no. 6: 1189-1195.

Research article
Published: 29 March 2016 in Langmuir
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Sticholysin II (StnII) is a pore-forming toxin that uses sphingomyelin (SM) as the recognition molecule in targeting membranes. After StnII monomers bind to SM, several toxin monomers act in concert to oligomerize into a functional pore. The regulation of StnII binding to SM, and the subsequent pore formation process, is not fully understood. In this study, we examined how the biophysical properties of bilayers, originating from variations in the SM structure, from the presence of sterol species, or from the presence of increasingly polyunsaturated glycerophospholipids, affected StnII-induced pore formation. StnII-induced pore formation, as determined from calcein permeabilization, was fastest in the pure unsaturated SM bilayers. In 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/saturated SM bilayers (4:1 molar ratio), pore formation became slower as the chain length of the saturated SMs increased from 14 up to 24 carbons. In the POPC/palmitoyl-SM (16:0-SM) 4:1 bilayers, SM could not support pore formation by StnII if dimyristoyl-PC was included at 1:1 stoichiometry with 16:0-SM, suggesting that free clusters of SM were required for toxin binding and/or pore formation. Cholesterol and other sterols facilitated StnII-induced pore formation markedly, but the efficiency did not appear to correlate with the sterol structure. Benzyl alcohol was more efficient than sterols in enhancing the pore formation process, suggesting that the effect on pore formation originated from alcohol-induced alteration of the hydrogen bonding network in the SM-containing bilayers. Finally, we observed that pore formation by StnII was enhanced in the PC/16:0-SM 4:1 bilayers, in which the PC was increasingly unsaturated. We conclude that the physical state of bilayer lipids greatly affected pore formation by StnII. Phase boundaries were not required for pore formation, although SM in a gel state attenuated pore formation.

ACS Style

Juan Palacios-Ortega; Sara García-Linares; Mia Åstrand; Abdullah Al Sazzad; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. Regulation of Sticholysin II-Induced Pore Formation by Lipid Bilayer Composition, Phase State, and Interfacial Properties. Langmuir 2016, 32, 3476 -3484.

AMA Style

Juan Palacios-Ortega, Sara García-Linares, Mia Åstrand, Abdullah Al Sazzad, José G. Gavilanes, Álvaro Martínez-Del-Pozo, J. Peter Slotte. Regulation of Sticholysin II-Induced Pore Formation by Lipid Bilayer Composition, Phase State, and Interfacial Properties. Langmuir. 2016; 32 (14):3476-3484.

Chicago/Turabian Style

Juan Palacios-Ortega; Sara García-Linares; Mia Åstrand; Abdullah Al Sazzad; José G. Gavilanes; Álvaro Martínez-Del-Pozo; J. Peter Slotte. 2016. "Regulation of Sticholysin II-Induced Pore Formation by Lipid Bilayer Composition, Phase State, and Interfacial Properties." Langmuir 32, no. 14: 3476-3484.