scholarly journals Molecular mechanism of pore formation by aerolysin-like proteins

2017 ◽  
Vol 372 (1726) ◽  
pp. 20160209 ◽  
Author(s):  
Marjetka Podobnik ◽  
Matic Kisovec ◽  
Gregor Anderluh
Keyword(s):  
Cell Biology ◽  
Pore Formation ◽  
Target Cells ◽  
Membrane Pores ◽  
Surface Molecules ◽  
Structural Details ◽  
Transmembrane Pores ◽  
Future Drug ◽  
Pore Forming Proteins ◽  
Unique Domain

Aerolysin-like pore-forming proteins are an important family of proteins able to efficiently damage membranes of target cells by forming transmembrane pores. They are characterized by a unique domain organization and mechanism of action that involves extensive conformational rearrangements. Although structures of soluble forms of many different members of this family are well understood, the structures of pores and their mechanism of assembly have been described only recently. The pores are characterized by well-defined β-barrels, which are devoid of any vestibular regions commonly found in other protein pores. Many members of this family are bacterial toxins; therefore, structural details of their transmembrane pores, as well as the mechanism of pore formation, are an important base for future drug design. Stability of pores and other properties, such as specificity for some cell surface molecules, make this family of proteins a useful set of molecular tools for molecular recognition and sensing in cell biology. This article is part of the themed issue ‘Membrane pores: from structure and assembly, to medicine and technology’.

scholarly journals Haemolytic actinoporins interact with carbohydrates using their lipid-binding module

2017 ◽  
Vol 372 (1726) ◽  
pp. 20160216 ◽  
Author(s):  
Koji Tanaka ◽  
Jose M. M. Caaveiro ◽  
Koldo Morante ◽  
Kouhei Tsumoto
Keyword(s):  
Protein Interactions ◽  
Pore Formation ◽  
Plasma Membranes ◽  
Lipid Binding ◽  
Target Cells ◽  
Sea Anemones ◽  
Molecular Systems ◽  
Membrane Pores ◽  
Living Organisms ◽  
Lipid Protein Interactions

Pore-forming toxins (PFTs) are proteins endowed with metamorphic properties that enable them to stably fold in water solutions as well as in cellular membranes. PFTs produce lytic pores on the plasma membranes of target cells conducive to lesions, playing key roles in the defensive and offensive molecular systems of living organisms. Actinoporins are a family of potent haemolytic toxins produced by sea anemones vigorously studied as a paradigm of α-helical PFTs, in the context of lipid–protein interactions, and in connection with nanopore technologies. We have recently reported that fragaceatoxin C (FraC), an actinoporin, engages biological membranes with a large adhesive motif allowing the simultaneous attachment of up to four lipid molecules prior to pore formation. Since actinoporins also interact with carbohydrates, we sought to understand the molecular and energetic basis of glycan recognition by FraC. By employing structural and biophysical methodologies, we show that FraC engages glycans with low affinity using its lipid-binding module. Contrary to other PFTs requiring separate domains for glycan and lipid recognition, the small single-domain actinoporins economize resources by achieving dual recognition with a single binding module. This mechanism could enhance the recruitment of actinoporins to the surface of target tissues in their marine environment. This article is part of the themed issue ‘Membrane pores: from structure and assembly, to medicine and technology’.

scholarly journals Repurposing a pore: highly conserved perforin-like proteins with alternative mechanisms

2017 ◽  
Vol 372 (1726) ◽  
pp. 20160212 ◽  
Author(s):  
Tao Ni ◽  
Robert J. C. Gilbert
Keyword(s):  
Retinoic Acid ◽  
Bone Morphogenetic Protein ◽  
Pore Formation ◽  
Membrane Attack Complex ◽  
Common Mechanism ◽  
Developmental Processes ◽  
Membrane Pores ◽  
Morphogenetic Protein ◽  
Specific Proteins ◽  
Pore Forming Proteins

Pore-forming proteins play critical roles in pathogenic attack and immunological defence. The membrane attack complex/perforin (MACPF) group of homologues represents, with cholesterol-dependent cytolysins, the largest family of such proteins. In this review, we begin by describing briefly the structure of MACPF proteins, outlining their common mechanism of pore formation. We subsequently discuss some examples of MACPF proteins likely implicated in pore formation or other membrane-remodelling processes. Finally, we focus on astrotactin and bone morphogenetic protein and retinoic acid-induced neural-specific proteins, highly conserved MACPF family members involved in developmental processes, which have not been well studied to date or observed to form a pore—and which data suggest may act by alternative mechanisms. This article is part of the themed issue ‘Membrane pores: from structure and assembly, to medicine and technology’.

scholarly journals Repair of a Bacterial Small β-Barrel Toxin Pore Depends on Channel Width

mBio ◽  
2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Gisela von Hoven ◽  
Amable J. Rivas ◽  
Claudia Neukirch ◽  
Martina Meyenburg ◽  
Qianqian Qin ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Cellular Responses ◽  
Channel Width ◽  
Target Cells ◽  
Alpha Toxin ◽  
Membrane Repair ◽  
Critical Determinant ◽  
Membrane Pores ◽  
Transmembrane Pores ◽  
Repair Mechanisms

ABSTRACT Membrane repair emerges as an innate defense protecting target cells against bacterial pore-forming toxins. Here, we report the first paradigm of Ca2+-dependent repair following attack by a small β-pore-forming toxin, namely, plasmid-encoded phobalysin of Photobacterium damselae subsp. damselae. In striking contrast, Vibrio cholerae cytolysin, the closest ortholog of phobalysin, subverted repair. Mutational analysis uncovered a role of channel width in toxicity and repair. Thus, the replacement of serine at phobalysin´s presumed channel narrow point with the bulkier tryptophan, the corresponding residue in Vibrio cholerae cytolysin (W318), modulated Ca2+ influx, lysosomal exocytosis, and membrane repair. And yet, replacing tryptophan (W318) with serine in Vibrio cholerae cytolysin enhanced toxicity. The data reveal divergent strategies evolved by two related small β-pore-forming toxins to manipulate target cells: phobalysin leads to fulminant perturbation of ion concentrations, closely followed by Ca2+ influx-dependent membrane repair. In contrast, V. cholerae cytolysin causes insidious perturbations and escapes control by the cellular wounded membrane repair-like response. IMPORTANCE Previous studies demonstrated that large transmembrane pores, such as those formed by perforin or bacterial toxins of the cholesterol-dependent cytolysin family, trigger rapid, Ca2+ influx-dependent repair mechanisms. In contrast, recovery from attack by the small β-pore-forming Staphylococcus aureus alpha-toxin or aerolysin is slow in comparison and does not depend on extracellular Ca2+. To further elucidate the scope of Ca2+ influx-dependent repair and understand its limitations, we compared the cellular responses to phobalysin and V. cholerae cytolysin, two related small β-pore-forming toxins which create membrane pores of slightly different sizes. The data indicate that the channel width of a small β-pore-forming toxin is a critical determinant of both primary toxicity and susceptibility to Ca2+-dependent repair. IMPORTANCE Previous studies demonstrated that large transmembrane pores, such as those formed by perforin or bacterial toxins of the cholesterol-dependent cytolysin family, trigger rapid, Ca2+ influx-dependent repair mechanisms. In contrast, recovery from attack by the small β-pore-forming Staphylococcus aureus alpha-toxin or aerolysin is slow in comparison and does not depend on extracellular Ca2+. To further elucidate the scope of Ca2+ influx-dependent repair and understand its limitations, we compared the cellular responses to phobalysin and V. cholerae cytolysin, two related small β-pore-forming toxins which create membrane pores of slightly different sizes. The data indicate that the channel width of a small β-pore-forming toxin is a critical determinant of both primary toxicity and susceptibility to Ca2+-dependent repair.

scholarly journals Decoding assembly of alpha-helical transmembrane pores through intermediate states

2021 ◽  
Author(s):  
Neethu Puthumadathil ◽  
Greeshma S Nair ◽  
Smrithi R Krishnan ◽  
Kozhinjampara R Mahendran
Keyword(s):  
Pore Formation ◽  
Single Channel ◽  
Sequence Specificity ◽  
Assembly Mechanism ◽  
Intermediate States ◽  
Transmembrane Pores ◽  
Voltage Dependent ◽  
Structural Assembly ◽  
Dynamics Simulations ◽  
Pore Forming Proteins

AbstractMembrane-active pore-forming alpha-helical peptides and proteins are well known for their dynamic assembly mechanism and it has been critical to delineate the pore-forming structures in the membrane. Previously, attempts have been made to elucidate their assembly mechanism and there is a large gap due to complex pathways by which these membrane-active pores impart their effect. Here we demonstrate the multi-step structural assembly pathway of alpha-helical peptide pores formed by a 37 amino-acid synthetic peptide, pPorU based on the natural porin from Corynebacterium urealyticum using single-channel electrical recordings. More specifically, we report detectable intermediates states during membrane insertion and pore formation of pPorU. The fully assembled pore is functional and exhibited unusually large stable conductance and voltage-dependent gating, generally applicable to a range of pore-forming proteins. Furthermore, we used rationally designed mutants to understand the role of specific amino acids in the assembly of these peptide pores. Mutant peptides that differ from wild-type peptides produced noisy, unstable intermediate states and low conductance pores, demonstrating sequence specificity in the pore-formation process supported by molecular dynamics simulations. We suggest that our study contributes to understanding the mechanism of action of alpha-helical pores and antimicrobial peptides and should be of broad interest to bioengineers to build peptide-based nanopore sensors.

scholarly journals Pore Forming Protein Induced Biomembrane Reorganization and Dynamics: A Focused Review

2021 ◽  
Vol 8 ◽  
Author(s):  
Ilanila Ilangumaran Ponmalar ◽  
Nirod K. Sarangi ◽  
Jaydeep K. Basu ◽  
K. Ganapathy Ayappa
Keyword(s):  
Pore Formation ◽  
Membrane Lipids ◽  
Md Simulations ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Brownian Diffusion ◽  
Target Cells ◽  
Listeriolysin O ◽  
Oligomeric State ◽  
Pore Forming Proteins

Pore forming proteins are a broad class of pathogenic proteins secreted by organisms as virulence factors due to their ability to form pores on the target cell membrane. Bacterial pore forming toxins (PFTs) belong to a subclass of pore forming proteins widely implicated in bacterial infections. Although the action of PFTs on target cells have been widely investigated, the underlying membrane response of lipids during membrane binding and pore formation has received less attention. With the advent of superresolution microscopy as well as the ability to carry out molecular dynamics (MD) simulations of the large protein membrane assemblies, novel microscopic insights on the pore forming mechanism have emerged over the last decade. In this review, we focus primarily on results collated in our laboratory which probe dynamic lipid reorganization induced in the plasma membrane during various stages of pore formation by two archetypal bacterial PFTs, cytolysin A (ClyA), an α-toxin and listeriolysin O (LLO), a β-toxin. The extent of lipid perturbation is dependent on both the secondary structure of the membrane inserted motifs of pore complex as well as the topological variations of the pore complex. Using confocal and superresolution stimulated emission depletion (STED) fluorescence correlation spectroscopy (FCS) and MD simulations, lipid diffusion, cholesterol reorganization and deviations from Brownian diffusion are correlated with the oligomeric state of the membrane bound protein as well as the underlying membrane composition. Deviations from free diffusion are typically observed at length scales below ∼130 nm to reveal the presence of local dynamical heterogeneities that emerge at the nanoscale—driven in part by preferential protein binding to cholesterol and domains present in the lipid membrane. Interrogating the lipid dynamics at the nanoscale allows us further differentiate between binding and pore formation of β- and α-PFTs to specific domains in the membrane. The molecular insights gained from the intricate coupling that occurs between proteins and membrane lipids and receptors during pore formation are expected to improve our understanding of the virulent action of PFTs.

scholarly journals NK cell-based cancer immunotherapy: from basic biology to clinical development

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Sizhe Liu ◽  
Vasiliy Galat ◽  
Yekaterina Galat4 ◽  
Yoo Kyung Annie Lee ◽  
Derek Wainwright ◽  
...  
Keyword(s):  
Cancer Immunotherapy ◽  
T Cell Activation ◽  
Cell Biology ◽  
Antigen Processing ◽  
Cell Activation ◽  
Nk Cell ◽  
Critical Role ◽  
Clinical Development ◽  
Target Cells ◽  
Immune Effector

AbstractNatural killer (NK) cell is a specialized immune effector cell type that plays a critical role in immune activation against abnormal cells. Different from events required for T cell activation, NK cell activation is governed by the interaction of NK receptors with target cells, independent of antigen processing and presentation. Due to relatively unsophisticated cues for activation, NK cell has gained significant attention in the field of cancer immunotherapy. Many efforts are emerging for developing and engineering NK cell-based cancer immunotherapy. In this review, we provide our current understandings of NK cell biology, ongoing pre-clinical and clinical development of NK cell-based therapies and discuss the progress, challenges, and future perspectives.

scholarly journals A Deadly Cargo: Gene Repertoire of Cytotoxic Effector Proteins in the Camelidae

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 304
Author(s):  
Ján Futas ◽  
Jan Oppelt ◽  
Pamela Anna Burger ◽  
Petr Horin
Keyword(s):  
Cytotoxic T Cells ◽  
Effector Proteins ◽  
Target Cells ◽  
Gene Repertoire ◽  
Interspecific Differences ◽  
Genes Encoding ◽  
Bactrian Camels ◽  
Pore Forming Proteins ◽  
Sequence Similarities ◽  
Cytotoxic Effector

Cytotoxic T cells and natural killer cells can kill target cells based on their expression and release of perforin, granulysin, and granzymes. Genes encoding these molecules have been only poorly annotated in camelids. Based on bioinformatic analyses of genomic resources, sequences corresponding to perforin, granulysin, and granzymes were identified in genomes of camelids and related ungulate species, and annotation of the corresponding genes was performed. A phylogenetic tree was constructed to study evolutionary relationships between the species analyzed. Re-sequencing of all genes in a panel of 10 dromedaries and 10 domestic Bactrian camels allowed analyzing their individual genetic polymorphisms. The data showed that all extant Old World camelids possess functional genes for two pore-forming proteins (PRF1, GNLY) and six granzymes (GZMA, GZMB, GZMH, GZMK, GZMM, and GZMO). All these genes were represented as single copies in the genome except the GZMH gene exhibiting interspecific differences in the number of loci. High protein sequence similarities with other camelid and ungulate species were observed for GZMK and GZMM. The protein variability in dromedaries and Bactrian camels was rather low, except for GNLY and chymotrypsin-like granzymes (GZMB, GZMH).

scholarly journals Desmosomal Molecules In and Out of Adhering Junctions: Normal and Diseased States of Epidermal, Cardiac and Mesenchymally Derived Cells

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Sebastian Pieperhoff ◽  
Mareike Barth ◽  
Steffen Rickelt ◽  
Werner W. Franke
Keyword(s):  
Cell Biology ◽  
Cell Types ◽  
Cell Junctions ◽  
Surface Molecules ◽  
Transmembrane Glycoprotein ◽  
Current Cell ◽  
Plakophilin 2 ◽  
Definition Of ◽  
Adhering Junctions ◽  
Cell Cell

Current cell biology textbooks mention only two kinds of cell-to-cell adhering junctions coated with the cytoplasmic plaques: the desmosomes (maculae adhaerentes), anchoring intermediate-sized filaments (IFs), and the actin microfilament-anchoring adherens junctions (AJs), including both punctate (puncta adhaerentia) and elongate (fasciae adhaerentes) structures. In addition, however, a series of other junction types has been identified and characterized which contain desmosomal molecules but do not fit the definition of desmosomes. Of these special cell-cell junctions containing desmosomal glycoproteins or proteins we review the composite junctions (areae compositae) connecting the cardiomyocytes of mature mammalian hearts and their importance in relation to human arrhythmogenic cardiomyopathies. We also emphasize the various plakophilin-2-positive plaques in AJs (coniunctiones adhaerentes) connecting proliferatively active mesenchymally-derived cells, including interstitial cells of the heart and several soft tissue tumor cell types. Moreover, desmoplakin has also been recognized as a constituent of the plaques of thecomplexus adhaerentesconnecting certain lymphatic endothelial cells. Finally, we emphasize the occurrence of the desmosomal transmembrane glycoprotein, desmoglein Dsg2, out of the context of any junction as dispersed cell surface molecules in certain types of melanoma cells and melanocytes. This broadening of our knowledge on the diversity of AJ structures indicates that it may still be too premature to close the textbook chapters on cell-cell junctions.

scholarly journals HLA restriction of human cytotoxic T lymphocytes specific for influenza virus. Poor recognition of virus associated with HLA A2.

1978 ◽  
Vol 148 (6) ◽  
pp. 1458-1467 ◽  
Author(s):  
A McMichael
Keyword(s):  
Influenza Virus ◽  
T Lymphocytes ◽  
Cytotoxic T Lymphocytes ◽  
Influenza A ◽  
Human Peripheral Blood ◽  
Peripheral Blood Lymphocytes ◽  
The Other ◽  
Target Cells ◽  
Surface Molecules ◽  
Human Peripheral Blood Lymphocytes

Cytotoxic T lymphocytes (CTL), specific for influenza A/X31 virus, were generated from human peripheral blood lymphocytes. These CTL lysed target cells that were infected with the same virus and that shared HLA A or B locus antigens. Minimal lysis was observed when HLA-D antigens were shared. Not all HLA A and B antigens were equally effective. Efficient lysis of target cells was seen when HLA A1, A3, B7, B8, B27 and BW21 were shared with the CTL, but when HLA A2 was the only shared antigen lysis was usually minimal. This deficiency in CTL function associated with HLA A2 was not absolute. It is suggested that the function of this antigen might be influenced by other surface molecules on the cell and in particular the other HLA products.

Genetically-Engineered Protease-Activated Triggers in a Pore-Forming Protein

1993 ◽  
Vol 330 ◽  
Author(s):  
Barbara Walker ◽  
Nathan Walsh ◽  
Hagan Bayley
Keyword(s):  
Genetic Engineering ◽  
Cancer Cells ◽  
Pore Formation ◽  
Polypeptide Chain ◽  
Genetically Engineered ◽  
Recognition Sequence ◽  
Selective Activation ◽  
Selective Destruction ◽  
Pore Forming Proteins ◽  
Central Loop

ABSTRACTProtease-activated triggers have been introduced Into a pore-forming protein, staphylococcal a-hemolysin (αHL). The hemolysin was remodeled by genetic engineering to form two-chain constructs with redundant polypeptide sequences at the central loop, the Integrity of which Is crucial for efficient pore formation. The new hemolysins are activated when the polypeptide extensions are removed by proteases. By alterating the protease recognition sequence in the loop, selective activation by specified proteases can be obtained. Protease-triggered pore-forming proteins might be used for the selective destruction of cancer cells that bear tumor-associated proteases. When certain two-chain constructs are treated with proteases, a full-length polypeptide chain forms as the result of a protease-mediated transpeptidation reaction. This reaction might be used to produce chimeric hemolysins that are Inaccessible by conventional routes.

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