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Croia L, Boscato Sopetto G, Zanella I, Caproni E, Gagliardi A, Tamburini S, König E, Benedet M, Di Lascio G, Corbellari R, Grandi A, Tomasi M, Grandi G. Immunogenicity of Escherichia coli Outer Membrane Vesicles: Elucidation of Humoral Responses against OMV-Associated Antigens. MEMBRANES 2023; 13:882. [PMID: 37999368 PMCID: PMC10673343 DOI: 10.3390/membranes13110882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/10/2023] [Accepted: 11/11/2023] [Indexed: 11/25/2023]
Abstract
Outer membrane vesicles (OMVs) produced by Gram-negative bacteria have emerged as a novel and flexible vaccine platform. OMVs can be decorated with foreign antigens and carry potent immunostimulatory components. Therefore, after their purification from the culture supernatant, they are ready to be formulated for vaccine use. It has been extensively demonstrated that immunization with engineered OMVs can elicit excellent antibody responses against the heterologous antigens. However, the definition of the conditions necessary to reach the optimal antibody titers still needs to be investigated. Here, we defined the protein concentrations required to induce antigen-specific antibodies, and the amount of antigen and OMVs necessary and sufficient to elicit saturating levels of antigen-specific antibodies. Since not all antigens can be expressed in OMVs, we also investigated the effectiveness of vaccines in which OMVs and purified antigens are mixed together without using any procedure for their physical association. Our data show that in most of the cases OMV-antigen mixtures are very effective in eliciting antigen-specific antibodies. This is probably due to the capacity of OMVs to "absorb" antigens, establishing sufficiently stable interactions that allow antigen-OMV co-presentation to the same antigen presenting cell. In those cases when antigen-OMV interaction is not sufficiently stable, the addition of alum to the formulation guarantees the elicitation of high titers of antigen-specific antibodies.
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Affiliation(s)
- Lorenzo Croia
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Giulia Boscato Sopetto
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Ilaria Zanella
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Elena Caproni
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Assunta Gagliardi
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Silvia Tamburini
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Enrico König
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Mattia Benedet
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Gabriele Di Lascio
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
| | - Riccardo Corbellari
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Alberto Grandi
- Toscana Life Sciences Foundation, Via Fiorentina 1, 53100 Siena, Italy; (E.C.); (A.G.); (S.T.); (M.B.); (G.D.L.); (A.G.)
- BiOMViS Srl, Via Fiorentina 1, 53100 Siena, Italy
| | - Michele Tomasi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
| | - Guido Grandi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; (L.C.); (G.B.S.); (I.Z.); (E.K.); (R.C.); (M.T.)
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2
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Stewart SE, Bird CH, Tabor RF, D'Angelo ME, Piantavigna S, Whisstock JC, Trapani JA, Martin LL, Bird PI. Analysis of Perforin Assembly by Quartz Crystal Microbalance Reveals a Role for Cholesterol and Calcium-independent Membrane Binding. J Biol Chem 2015; 290:31101-12. [PMID: 26542805 DOI: 10.1074/jbc.m115.683078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Indexed: 12/26/2022] Open
Abstract
Perforin is an essential component in the cytotoxic lymphocyte-mediated cell death pathway. The traditional view holds that perforin monomers assemble into pores in the target cell membrane via a calcium-dependent process and facilitate translocation of cytotoxic proteases into the cytoplasm to induce apoptosis. Although many studies have examined the structure and role of perforin, the mechanics of pore assembly and granzyme delivery remain unclear. Here we have employed quartz crystal microbalance with dissipation monitoring (QCM-D) to investigate binding and assembly of perforin on lipid membranes, and show that perforin monomers bind to the membrane in a cooperative manner. We also found that cholesterol influences perforin binding and activity on intact cells and model membranes. Finally, contrary to current thinking, perforin efficiently binds membranes in the absence of calcium. When calcium is added to perforin already on the membrane, the QCM-D response changes significantly, indicating that perforin becomes membranolytic only after calcium binding.
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Affiliation(s)
| | | | | | | | | | - James C Whisstock
- From the Department of Biochemistry and Molecular Biology, Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800 and
| | - Joseph A Trapani
- the Cancer Cell Death Laboratory, Cancer Immunology Program, Peter MacCallum Cancer Centre, St Andrew's Place, East Melbourne, Victoria 3002, Australia
| | | | - Phillip I Bird
- From the Department of Biochemistry and Molecular Biology,
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3
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Stewart SE, D'Angelo ME, Piantavigna S, Tabor RF, Martin LL, Bird PI. Assembly of streptolysin O pores assessed by quartz crystal microbalance and atomic force microscopy provides evidence for the formation of anchored but incomplete oligomers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:115-26. [DOI: 10.1016/j.bbamem.2014.10.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/20/2014] [Accepted: 10/03/2014] [Indexed: 11/24/2022]
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4
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Stewart SE, Kondos SC, Matthews AY, D'Angelo ME, Dunstone MA, Whisstock JC, Trapani JA, Bird PI. The perforin pore facilitates the delivery of cationic cargos. J Biol Chem 2014; 289:9172-81. [PMID: 24558045 DOI: 10.1074/jbc.m113.544890] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cytotoxic lymphocytes eliminate virally infected or neoplastic cells through the action of cytotoxic proteases (granzymes). The pore-forming protein perforin is essential for delivery of granzymes into the cytoplasm of target cells; however the mechanism of this delivery is incompletely understood. Perforin contains a membrane attack complex/perforin (MACPF) domain and oligomerizes to form an aqueous pore in the plasma membrane; therefore the simplest (and best supported) model suggests that granzymes passively diffuse through the perforin pore into the cytoplasm of the target cell. Here we demonstrate that perforin preferentially delivers cationic molecules while anionic and neutral cargoes are delivered inefficiently. Furthermore, another distantly related pore-forming MACPF protein, pleurotolysin (from the oyster mushroom), also favors the delivery of cationic molecules, and efficiently delivers human granzyme B. We propose that this facilitated diffusion is due to conserved features of oligomerized MACPF proteins, which may include an anionic lumen.
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5
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Feil SC, Ascher DB, Kuiper MJ, Tweten RK, Parker MW. Structural studies of Streptococcus pyogenes streptolysin O provide insights into the early steps of membrane penetration. J Mol Biol 2014; 426:785-92. [PMID: 24316049 PMCID: PMC4323271 DOI: 10.1016/j.jmb.2013.11.020] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/11/2013] [Accepted: 11/22/2013] [Indexed: 12/22/2022]
Abstract
Cholesterol-dependent cytolysins (CDCs) are a large family of bacterial toxins that exhibit a dependence on the presence of membrane cholesterol in forming large pores in cell membranes. Significant changes in the three-dimensional structure of these toxins are necessary to convert the soluble monomeric protein into a membrane pore. We have determined the crystal structure of the archetypical member of the CDC family, streptolysin O (SLO), a virulence factor from Streptococcus pyogenes. The overall fold is similar to previously reported CDC structures, although the C-terminal domain is in a different orientation with respect to the rest of the molecule. Surprisingly, a signature stretch of CDC sequence called the undecapeptide motif, a key region involved in membrane recognition, adopts a very different structure in SLO to that of the well-characterized CDC perfringolysin O (PFO), although the sequences in this region are identical. An analysis reveals that, in PFO, there are complementary interactions between the motif and the rest of domain 4 that are lost in SLO. Molecular dynamics simulations suggest that the loss of a salt bridge in SLO and a cation-pi interaction are determining factors in the extended conformation of the motif, which in turn appears to result in a greater flexibility of the neighboring L1 loop that houses a cholesterol-sensing motif. These differences may explain the differing abilities of SLO and PFO to efficiently penetrate target cell membranes in the first step of toxin insertion into the membrane.
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Affiliation(s)
- Susanne C Feil
- ACRF Rational Drug Discovery Centre, Biota Structural Biology Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - David B Ascher
- ACRF Rational Drug Discovery Centre, Biota Structural Biology Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Michael J Kuiper
- Victorian Life Sciences Computation Initiative, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Rodney K Tweten
- Department of Microbiology and Immunology, University of Oklahoma, Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Michael W Parker
- ACRF Rational Drug Discovery Centre, Biota Structural Biology Laboratory, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia; Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.
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6
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Time course of virulence factors produced by group A streptococcus during a food-borne epidemic. J Infect Chemother 2011; 18:35-40. [PMID: 21750972 DOI: 10.1007/s10156-011-0280-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 06/26/2011] [Indexed: 10/18/2022]
Abstract
We studied the protein amount and activity of the major virulence factors hemolysin, cysteine protease streptococcal pyrogenic exotoxin B (SpeB), and NAD glycohydrolase (NADase), which are produced by Streptococcus pyogenes type T-25, with a food poisoning outbreak. The three virulence factors were analyzed by activity and amount of protein using supernatants at 2-30 h of culture. All these virulence factors were confirmed by their activity. Streptolysin O (SLO), SpeB, and NADase were immunochemically confirmed at protein level by Western blot analysis. Two hemolytic forms (70 and 60 kDa) of SLO were identified. SpeB was detected as a 44-kDa precursor form and a 30-kDa mature form. NADase was 50 kDa. SLO protein peaked at 8 h of culture, which corresponded with the hemolytic activity peak. Conversion from precursor to SpeB protein peaked at 14 h of culture. The conversion peak corresponded to the activity expression time. Also, mature SpeB protein peaked at 24 h of culture and corresponded to SpeB activity peak. Electrophoretic analysis clarified the relationship between SLO protein and SpeB protein, although amounts of SLO and SpeB have been reported to be inversely proportional to activity. NADase protein peaked at 12 h of culture, but protein level did not correspond to the peak. Because the NADase protein peak was closer to SpeB activity than SLO protein, our results suggested NADase protein was degraded at 12 h of culture. The time course production of these virulence factors is discussed.
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Kao CY, Los FCO, Huffman DL, Wachi S, Kloft N, Husmann M, Karabrahimi V, Schwartz JL, Bellier A, Ha C, Sagong Y, Fan H, Ghosh P, Hsieh M, Hsu CS, Chen L, Aroian RV. Global functional analyses of cellular responses to pore-forming toxins. PLoS Pathog 2011; 7:e1001314. [PMID: 21408619 PMCID: PMC3048360 DOI: 10.1371/journal.ppat.1001314] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 02/04/2011] [Indexed: 01/12/2023] Open
Abstract
Here we present the first global functional analysis of cellular responses to pore-forming toxins (PFTs). PFTs are uniquely important bacterial virulence factors, comprising the single largest class of bacterial protein toxins and being important for the pathogenesis in humans of many Gram positive and Gram negative bacteria. Their mode of action is deceptively simple, poking holes in the plasma membrane of cells. The scattered studies to date of PFT-host cell interactions indicate a handful of genes are involved in cellular defenses to PFTs. How many genes are involved in cellular defenses against PFTs and how cellular defenses are coordinated are unknown. To address these questions, we performed the first genome-wide RNA interference (RNAi) screen for genes that, when knocked down, result in hypersensitivity to a PFT. This screen identifies 106 genes (∼0.5% of genome) in seven functional groups that protect Caenorhabditis elegans from PFT attack. Interactome analyses of these 106 genes suggest that two previously identified mitogen-activated protein kinase (MAPK) pathways, one (p38) studied in detail and the other (JNK) not, form a core PFT defense network. Additional microarray, real-time PCR, and functional studies reveal that the JNK MAPK pathway, but not the p38 MAPK pathway, is a key central regulator of PFT-induced transcriptional and functional responses. We find C. elegans activator protein 1 (AP-1; c-jun, c-fos) is a downstream target of the JNK-mediated PFT protection pathway, protects C. elegans against both small-pore and large-pore PFTs and protects human cells against a large-pore PFT. This in vivo RNAi genomic study of PFT responses proves that cellular commitment to PFT defenses is enormous, demonstrates the JNK MAPK pathway as a key regulator of transcriptionally-induced PFT defenses, and identifies AP-1 as the first cellular component broadly important for defense against large- and small-pore PFTs. The plasma membrane surrounds cells and protects their interior from the environment and from attack by disease-causing agents like bacteria and viruses. Bacteria that cause disease have discovered that an effective way to attack cells is to secrete proteins (pore-forming toxins) that breach, i.e., form holes in, the plasma membrane. How cells deal with and survive this kind of attack is poorly understood. Here, we report on the first large-scale study of the genes and mRNA transcripts that respond to pore-forming toxin attack in cells. We find that a remarkable portion, >0.5%, of the cell's genome protects it against pore-forming toxins. These data led us to look more closely at mitogen-activated protein kinase pathways as regulators of pore-forming toxin defenses. We find that half of the PFT-induced protective response is controlled by a single, conserved signaling pathway in cells, which controls a complex array of downstream targets and which protects against both large pore and small pore toxins. Our results indicate that defense against pore-forming toxins is a very ancient defense that utilizes a much more complex and extensive response in cells than previously demonstrated.
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Affiliation(s)
- Cheng-Yuan Kao
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Ferdinand C. O. Los
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Danielle L. Huffman
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Shinichiro Wachi
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Nicole Kloft
- Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, Mainz, Germany
| | - Matthias Husmann
- Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, Mainz, Germany
| | - Valbona Karabrahimi
- Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Quebec, Canada
| | - Jean-Louis Schwartz
- Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Quebec, Canada
| | - Audrey Bellier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Christine Ha
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Youn Sagong
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Hui Fan
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, United States of America
| | - Partho Ghosh
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, United States of America
| | - Mindy Hsieh
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Chih-Shen Hsu
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Li Chen
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Raffi V. Aroian
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
- * E-mail:
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Harris JR, Lewis RJ, Baik C, Pokrajac L, Billington SJ, Palmer M. Cholesterol microcrystals and cochleate cylinders: attachment of pyolysin oligomers and domain 4. J Struct Biol 2010; 173:38-45. [PMID: 20682347 DOI: 10.1016/j.jsb.2010.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 07/16/2010] [Accepted: 07/27/2010] [Indexed: 11/15/2022]
Abstract
Using an established organic solvent injection procedure for the preparation of aqueous cholesterol microcrystal suspensions, it has now been shown that a new, hollow, cylindrical, tightly-coiled, multi-bilayer form of cholesterol can be generated, termed the cochleate cylinder. Cholesterol cochleate cylinders are formed in larger numbers at intermediate temperatures (40-75°C) but are not formed at 100°C. The structure of the cholesterol microcrystals and cochleate cylinders is shown in negatively stained electron micrographs. Oligomerization and attachment of pyolysin to cholesterol microcrystals and cochleate cylinders is shown, as is the attachment of the pyolysin "cholesterol-binding" domain 4 (D4) fragment. The bound D4 domain forms a linear array on the two planar surfaces and edges of the cholesterol microcrystals and a quasi helical array on the surface of the cochleate cylinders. Little evidence has been obtained to support the possibility that interaction or hetero-oligomerization can occur between intact pyolysin and the pyolysin D4 fragment on the surface of cholesterol microcrystals. Using immobilized cholesterol crystals attached to a carbon support film, single-sided linear labelling of the cholesterol surface with pyolysin D4 has been achieved, which correlates well with the images from the microcrystal suspensions and our earlier data using non-cytolytic streptolysin O mutants.
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Affiliation(s)
- J Robin Harris
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle-upon-Tyne NE2 4HH, UK.
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Abstract
Pore-forming toxins (PFT) comprise a large, structurally heterogeneous group of bacterial protein toxins. Nucleated target cells mount complex responses which allow them to survive moderate membrane damage by PFT. Autophagy has recently been implicated in responses to various PFT, but how this process is triggered is not known, and the significance of the phenomenon is not understood. Here, we show that S. aureus α-toxin, Vibrio cholerae cytolysin, streptolysin O and E. coli haemolysin activate two pathways leading to autophagy. The first pathway is triggered via AMP-activated protein kinase (AMPK). AMPK is a major energy sensor which induces autophagy by inhibiting the target of rapamycin complex 1 (TORC1) in response to a drop of the cellular ATP/AMP-ratio, as is also observed in response to membrane perforation. The second pathway is activated by the conserved eIF2α-kinase GCN2, which causes global translational arrest and promotes autophagy in response to starvation. The latter could be accounted for by impaired amino acid transport into target cells. Notably, PKR, an eIF2α-kinase which has been implicated in autophagy induction during viral infection, was also activated upon membrane perforation, and evidence was obtained that phosphorylation of eIF2α is required for the accumulation of autophagosomes in α-toxin-treated cells. Treatment with 3-methyl-adenine inhibited autophagy and disrupted the ability of cells to recover from sublethal attack by S. aureus α-toxin. We propose that PFT induce pro-autophagic signals through membrane perforation–dependent nutrient and energy depletion, and that an important function of autophagy in this context is to maintain metabolic homoeostasis.
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Kloft N, Busch T, Neukirch C, Weis S, Boukhallouk F, Bobkiewicz W, Cibis I, Bhakdi S, Husmann M. Pore-forming toxins activate MAPK p38 by causing loss of cellular potassium. Biochem Biophys Res Commun 2009; 385:503-6. [PMID: 19497299 DOI: 10.1016/j.bbrc.2009.05.121] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 05/14/2009] [Indexed: 01/15/2023]
Abstract
Mitogen activated protein kinase (MAPK) p38 has emerged as a survival protein in cells that are attacked by bacterial toxins forming small membrane pores. Activation of p38 by pore forming toxins (PFT) has been attributed to osmotic stress, but here we show that loss of K+ is likely to be the critical parameter. Several lines of evidence support this conclusion: first, osmoprotection did not prevent p38-phosphorylation in alpha-toxin-loaded cells. Second, treatment of cells with a K+ ionophore, or simple incubation in K+-free medium sufficed to cause robust p38-phosphorylation. Third, media containing high [K+] prevented p38-activation by Staphylococcus aureus alpha-toxin, Vibrio cholerae cytolysin (VCC), Streptolysin O (SLO), or Escherichia coli hemolysin (HlyA), but did not impair activation by H2O2. Fourth, potential roles of LPS, TLR4, or calcium-influx were ruled out. Therefore, we propose that PFT trigger the p38 MAPK-pathway by causing loss of cellular K+.
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Affiliation(s)
- Nicole Kloft
- Institut für Medizinische Mikrobiologie und Hygiene, Universitätsmedizin, Johannes Gutenberg-Universität, Mainz, Germany
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11
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Metz M, Magerl M, Kühl NF, Valeva A, Bhakdi S, Maurer M. Mast cells determine the magnitude of bacterial toxin-induced skin inflammation. Exp Dermatol 2009; 18:160-6. [DOI: 10.1111/j.1600-0625.2008.00778.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Brunk I, Blex C, Speidel D, Brose N, Ahnert-Hilger G. Ca2+-dependent activator proteins of secretion promote vesicular monoamine uptake. J Biol Chem 2008; 284:1050-6. [PMID: 19008227 DOI: 10.1074/jbc.m805328200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(2+)-dependent activator proteins of secretion (CAPS) 1 and 2 are essential regulators of synaptic vesicle and large dense core vesicle priming in mammalian neurons and neuroendocrine cells. CAPS1 appears to have an additional and as yet unexplained function in vesicular catecholamine uptake or storage as CAPS1-deficient chromaffin cells exhibit strongly reduced vesicular catecholamine levels. Here we describe a role of CAPS proteins in vesicular monoamine uptake. Both CAPS1 and CAPS2 promote monoamine uptake and storage mediated by the vesicular monoamine transporters VMAT1 and VMAT2. Monoamine uptake of vesicular preparations from embryonic brains of CAPS1 deletion mutants is decreased as compared with corresponding preparations from wild type littermates, and anti-CAPS1 or anti-CAPS2 antibodies inhibit monoamine sequestration by synaptic vesicles from adult mouse brain. In addition, overexpression of CAPS1 or CAPS2 enhances vesicular monoamine uptake in Chinese hamster ovary cells that stably express VMAT1 or VMAT2. CAPS function has been linked to the heterotrimeric GTPase G(o), which modulates vesicular monoamine uptake. We found that the expression of CAPS1 is decreased in brain membrane preparations from mice lacking G(o2)alpha, which may explain the reduced monoamine uptake by G(o2)alpha-deficient synaptic vesicles. Accordingly, anti-CAPS1 antibodies do not further reduce monoamine uptake by G(o2)alpha-deficient synaptic vesicles, whereas antibodies directed against CAPS2, whose expression is not altered in G(o2)alpha-deficient brain, still reduce monoamine uptake into G(o2)alpha-deficient vesicles. We conclude that CAPS proteins are involved in optimizing vesicular monoamine uptake and storage mediated by VMAT1 and VMAT2.
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Affiliation(s)
- Irene Brunk
- AG Functional Cell Biology, Institute for Integrative Neuroanatomy, Charité Center 2 for Basic Medicine, Philippstr. 12, D-10115 Berlin, Germany
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Brunk I, Blex C, Sanchis-Segura C, Sternberg J, Perreau-Lenz S, Bilbao A, Hörtnagl H, Baron J, Juranek J, Laube G, Birnbaumer L, Spanagel R, Ahnert-Hilger G. Deletion of Go2alpha abolishes cocaine-induced behavioral sensitization by disturbing the striatal dopamine system. FASEB J 2008; 22:3736-46. [PMID: 18606864 DOI: 10.1096/fj.08-111245] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The alpha-subunits of the trimeric Go class of GTPases, comprising the splice variants Go1alpha and Go2alpha, are abundantly expressed in brain and reside on both plasma membrane and synaptic vesicles. Go2alpha is involved in the vesicular storage of monoamines but its physiological relevance is still obscure. We now show that genetic depletion of Go2alpha reduces motor activity induced by dopamine-enhancing drugs like cocaine, as repeated injections of cocaine fail to provoke behavioral sensitization in Go2alpha(-/-) mice. In Go2alpha(-/-) mice, D1 receptor signaling in the striatum is attenuated due to a reduced expression of Golf alpha and Gs alpha. Following cocaine treatment, Go2alpha(-/-) mice have lower D1 and higher D2 receptor amounts compared to wild-type mice. The lack of behavioral sensitization correlates with reduced dopamine levels in the striatum and decreased expression of tyrosine hydroxylase. One reason for the neurochemical changes may be a reduced uptake of monoamines by synaptic vesicles from Go2alpha(-/-) mice as a consequence of a lowered set point for filling. We conclude that Go2alpha optimizes vesicular filling which is instrumental for normal dopamine functioning and for the development of drug-induced behavioral sensitization.
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Affiliation(s)
- Irene Brunk
- Institute for Integrative Neuroanatomy, Center for Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Aboulwafa M, Saier MH. Characterization of the E. coli glucose permease fused to the maltose-binding protein. J Basic Microbiol 2008; 48:3-9. [PMID: 18247392 DOI: 10.1002/jobm.200700263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The ptsG gene that encodes the major glucose transporter of Escherichia coli, II Glc, was inserted into a pMALE-amp r expression vector down-stream of the malE gene which encodes the E. coli maltose-binding protein (MBP). II Glc-MBP in the 2 h high speed supernatant of cell lysates eluted from a gel filtration column showing two activity peaks. The glucose-6-phosphate-dependent transphosphorylation (TP) activity of the membrane bound oligomeric peak 1 showed substrate inhibition while that of the soluble monomeric peak 2 did not. Purification of peak 2 yielded activity with weak substrate inhibition, and further gel filtration analyses showed that upon purification, some of the monomeric II Glc-MBP associated to higher molecular size forms. Assays of the phosphoenolpyruvate-dependent and transphosphorylation reactions showed that the specific activity of the purified enzyme from peak 1 was approximately double that from peak 2. The results show that the monomeric II Glc-MBP exhibits no substrate inhibition although the oligomeric form does. Purification promotes subunit association, an increase in catalytic activity, and restoration of substrate inhibition.
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Affiliation(s)
- Mohammad Aboulwafa
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
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15
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Gauthier BR, Duhamel DL, Iezzi M, Theander S, Saltel F, Fukuda M, Wehrle-Haller B, Wollheim CB. Synaptotagmin VII splice variants alpha, beta, and delta are expressed in pancreatic beta-cells and regulate insulin exocytosis. FASEB J 2007; 22:194-206. [PMID: 17709608 DOI: 10.1096/fj.07-8333com] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Synaptotagmins (SYT) are calcium-binding proteins that participate in regulated exocytosis. Although SYTI to IX isoforms are expressed in insulin-producing cell lines, hitherto only SYTIX has been associated with native beta-cell insulin granules and implicated in exocytosis. SYTVII was also proposed to regulate insulin exocytosis, but its subcellular location and number of alternative splice variants produced remain controversial. Only transcripts of SYTVII alpha, beta, and a novel splice variant delta are expressed in beta-cells and INS-1E cells. Western blotting revealed that INS-1E cells predominantly produced SYTVII alpha and low levels of SYTVII beta, whereas SYTVII delta was undetectable. The protein colocalized with insulin granules but not with synaptic-like microvesicles. Overexpression of SYTVII alpha resulted in decreased insulin granule content with a concomitant translocation of the variant to the plasma membrane, while SYTVII beta retained largely a granular pattern. Overexpressed SYTVII delta exhibited a distribution different to that of insulin granules and inhibited exocytosis when assessed by whole cell patch clamp capacitance recording. Silencing of SYTVII alpha by targeted RNA interference suppressed secretion, while repression of beta slightly increased release. Our results demonstrate that SYTVII is expressed on insulin granules and that only SYTVII alpha is implicated in exocytosis under physiological conditions.
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Affiliation(s)
- Benoit R Gauthier
- Department of Cell Physiology and Metabolism, University Medical Center, 1211 Geneva 4, Switzerland.
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16
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Lippert U, Ferrari DM, Jahn R. Endobrevin/VAMP8 mediates exocytotic release of hexosaminidase from rat basophilic leukaemia cells. FEBS Lett 2007; 581:3479-84. [PMID: 17618625 DOI: 10.1016/j.febslet.2007.06.057] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2007] [Revised: 06/17/2007] [Accepted: 06/21/2007] [Indexed: 10/23/2022]
Abstract
Mast cells are important players in innate immunity and mediate allergic responses. Upon stimulation, they release biologically active mediators including histamine, cytokines and lysosomal hydrolases. We used permeabilized rat basophilic leukaemia cells as model to identify R-SNAREs (soluble NSF (N-ethylmaleimide-sensitive fusion protein)) mediating exocytosis of hexosaminidase from mast cells. Of a complete set of recombinant mammalian R-SNAREs, only vesicle associated membrane protein (VAMP8)/endobrevin consistently blocked hexosaminidase release, which was also insensitive to treatment with clostridial neurotoxins. Thus, VAMP8, which also mediates fusion of late endosomes and lysosomes, plays a major role in hexosaminidase release, strengthening the view that mast cell granules share properties of both secretory granules and lysosomes.
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Affiliation(s)
- Undine Lippert
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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17
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Haugwitz U, Bobkiewicz W, Han SR, Beckmann E, Veerachato G, Shaid S, Biehl S, Dersch K, Bhakdi S, Husmann M. Pore-forming Staphylococcus aureus alpha-toxin triggers epidermal growth factor receptor-dependent proliferation. Cell Microbiol 2006; 8:1591-600. [PMID: 16984414 DOI: 10.1111/j.1462-5822.2006.00733.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Staphylococcal alpha-toxin is an archetypal killer protein that homo-oligomerizes in target cells to create small transmembrane pores. The membrane-perforating beta-barrel motif is a conserved attack element of cytolysins of Gram-positive and Gram-negative bacteria. Following the recognition that nucleated cells can survive membrane permeabilization, a profile of abundant transcripts was obtained in transiently perforated keratinocytes. Several immediate early genes were found to be upregulated, reminiscent of the cellular response to growth factors. Cell cycle analyses revealed doubling of S + G2/M phase cells 26 h post toxin treatment. Determination of cell counts uncovered that after an initial drop, numbers increased to exceed the controls after 2 days. A non-lytic alpha-toxin mutant remained without effect. The alpha-toxin pore is too small to allow egress of cytosolic growth factors, and evidence was instead obtained for growth signalling via the epidermal growth factor receptor (EGFR). Inhibition of the EGFR or of EGFR-proligand-processing blocked the mitogenic effect of alpha-toxin. Western blots with phospho-specific antibodies revealed activation of the EGFR, and of the adapter protein Shc. Immediate early response and proliferation upon transient plasma membrane pore formation by bacterial toxins may represent a novel facet of the complex interaction between pathogen and host.
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Affiliation(s)
- Ulrike Haugwitz
- Institute of Medical Microbiology and Hygiene, Johannes Gutenberg-University, Hochhaus am Augustusplatz, Mainz, Germany
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18
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Husmann M, Dersch K, Bobkiewicz W, Beckmann E, Veerachato G, Bhakdi S. Differential role of p38 mitogen activated protein kinase for cellular recovery from attack by pore-forming S. aureus alpha-toxin or streptolysin O. Biochem Biophys Res Commun 2006; 344:1128-34. [PMID: 16643845 DOI: 10.1016/j.bbrc.2006.03.241] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 03/31/2006] [Indexed: 11/26/2022]
Abstract
Following the observation that cells are able to recover from membrane lesions incurred by Staphylococcus aureus alpha-toxin and streptolysin O (SLO), we investigated the role of p38 in this process. p38 phosphorylation occurred in response to attack by both toxins, commencing within minutes after toxin treatment and waning after several hours. While SLO reportedly activates p38 via ASK1 and ROS, we show that this pathway does not play a major role for p38 induction in alpha-toxin-treated cells. Strikingly divergent effects of p38 blockade were noted depending on the toxin employed. In the case of alpha-toxin, inhibition of p38 within the time frame of its activation led to disruption of the recovery process and to cell death. In contrast, blockade of p38 in SLO permeabilized cells did not affect the capacity of the cells to replenish their ATP stores.
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Affiliation(s)
- Matthias Husmann
- Institute of Medical Microbiology and Hygiene, Johannes Gutenberg-University, Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
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19
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Kimoto H, Fujii Y, Hirano S, Yokota Y, Taketo A. Expression of Recombinant Streptolysin O and Specific Antibody Production. J Mol Microbiol Biotechnol 2006; 10:64-8. [PMID: 16491027 DOI: 10.1159/000090349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Streptolysin O (SLO), an oxygen-labile cytolysin, is the cholesterol-binding exotoxin of hemolytic streptococci. Besides microbiological and pathological interests, this cytolysin has been used as a tool for permeabilization of biomembranes. SLO serves as a diagnostic reagent for determination of anti-SLO antibody titer in streptococcal infection. Availability of highly purified SLO, however, has been limited by low yield in streptococcal culture and purification process. Present subcloning of mature-type full-length SLO gene into an expression vector having strictly controllable araBAD promoter enabled efficient production of the cytolysin. Further, anti-SLO antibody with high specificity was obtained by immunizing with purified SLO protein.
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Affiliation(s)
- Hisashi Kimoto
- Department of Molecular Genetics, Fukui University, Matsuoka, Japan.
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20
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Bird CH, Sun J, Ung K, Karambalis D, Whisstock JC, Trapani JA, Bird PI. Cationic sites on granzyme B contribute to cytotoxicity by promoting its uptake into target cells. Mol Cell Biol 2005; 25:7854-67. [PMID: 16107729 PMCID: PMC1190293 DOI: 10.1128/mcb.25.17.7854-7867.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Granzyme B (GrB) is a key effector of cytotoxic lymphocyte-mediated cell death. It is delivered to target cells bound to the proteoglycan serglycin, but how it crosses the plasma membrane and accesses substrates in the cytoplasm is poorly understood. Here we identify two cationic sequences on GrB that facilitate its binding and uptake. Mutation of cationic sequence 1 (cs1) prevents accumulation of GrB in a distinctive intracellular compartment and reduces cytotoxicity 20-fold. Mutation of cs2 reduces accumulation in this intracellular compartment and cytotoxicity two- to threefold. We also show that GrB-mediated cytotoxicity is abrogated by heparin and that target cells deficient in cell surface sulfate or glycosaminoglycans resist GrB. However, heparin does not completely prevent GrB internalization and chondroitin 4-sulfate does not inhibit cytotoxicity, suggesting that glycosaminoglycans are not essential GrB receptors. We propose that GrB enters cells by nonselective adsorptive pinocytosis, exchanging from chondroitin sulfate on serglycin to anionic components of the cell surface. In this electrostatic "exchange-adsorption" model, cs1 and cs2 participate in binding of GrB to the cell surface, thereby promoting its uptake and eventual release into the cytoplasm.
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Affiliation(s)
- Catherina H Bird
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
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21
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Cooper RA, Papakrivos J, Lane KD, Fujioka H, Lingelbach K, Wellems TE. PfCG2, a Plasmodium falciparum protein peripherally associated with the parasitophorous vacuolar membrane, is expressed in the period of maximum hemoglobin uptake and digestion by trophozoites. Mol Biochem Parasitol 2005; 144:167-76. [PMID: 16183150 DOI: 10.1016/j.molbiopara.2005.07.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 07/03/2005] [Accepted: 07/14/2005] [Indexed: 10/25/2022]
Abstract
A Plasmodium falciparum gene closely linked to the chloroquine resistance locus encodes PfCG2, a predicted 320-330kDa protein. In the parasitized erythrocyte, PfCG2 expression rises sharply in the trophozoite stage and is detected in electron-dense patches along the parasitophorous vacuolar membrane (PVM), in the cytoplasm and in the digestive vacuole (DV). Results of extraction and partitioning experiments show that PfCG2 is a peripheral membrane protein. Exposure of trophozoite-infected erythrocytes to trypsin-containing buffer after streptolysin O permeabilization indicates that PfCG2 is exposed to the erythrocyte cytosol at the outer face of the PVM. PfCG2 is highly susceptible to hydrolysis by aspartic and cysteine proteases and shows dose-dependent accumulation in the presence of protease inhibitors. These results suggest that PfCG2 is delivered from the outside face of the PVM to the DV, where it is broken down by parasite proteases. PfCG2 interacts with erythrocyte cytoplasm and may be associated with processes of hemoglobin uptake and digestion by erythrocytic-stage parasites.
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Affiliation(s)
- Roland A Cooper
- Laboratory of Malaria and Vector Research, Twinbrook III, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA
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22
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Valeva A, Walev I, Kemmer H, Weis S, Siegel I, Boukhallouk F, Wassenaar TM, Chavakis T, Bhakdi S. Binding of Escherichia coli hemolysin and activation of the target cells is not receptor-dependent. J Biol Chem 2005; 280:36657-63. [PMID: 16131494 DOI: 10.1074/jbc.m507690200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Production of a single cysteine substitution mutant, S177C, allowed Escherichia coli hemolysin (HlyA) to be radioactively labeled with tritiated N-ethylmaleimide without affecting biological activity. It thus became possible to study the binding characteristics of HlyA as well as of toxin mutants in which one or both acylation sites were deleted. All toxins bound to erythrocytes and granulocytes in a nonsaturable manner. Only wild-type toxin and the lytic monoacylated mutant stimulated production of superoxide anions in granulocytes. An oxidative burst coincided with elevation of intracellular Ca(2+), which was likely because of passive influx of Ca(2+) through the toxin pores. Competition experiments showed that binding to the cells was receptor-independent, and preloading of cells with a nonlytic HlyA mutant did not abrogate the respiratory burst provoked by a subsequent application of wild-type HlyA. In contrast to a previous report, expression or activation of the beta(2) integrin lymphocyte function-associated antigen-1 did not affect binding of HlyA. We conclude that HlyA binds nonspecifically to target cells and a receptor is involved neither in causing hemolysis nor in triggering cellular reactions.
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Affiliation(s)
- Angela Valeva
- Institute of Medical Microbiology and Hygiene, University of Mainz, D-55101 Mainz, Germany.
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23
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Schatter B, Jin S, Löffelholz K, Klein J. Cross-talk between phosphatidic acid and ceramide during ethanol-induced apoptosis in astrocytes. BMC Pharmacol 2005; 5:3. [PMID: 15694004 PMCID: PMC549038 DOI: 10.1186/1471-2210-5-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Accepted: 02/04/2005] [Indexed: 01/08/2023] Open
Abstract
Background Ethanol inhibits proliferation in astrocytes, an effect that was recently linked to the suppression of phosphatidic acid (PA) formation by phospholipase D (PLD). The present study investigates ethanol's effect on the induction of apoptosis in astrocytes and the formation of ceramide, an apoptotic signal. Evidence is presented that the formation of PA and ceramide may be reciprocally linked during ethanol exposure. Results In cultured rat cortical astrocytes, ethanol (0.3–1 %, v/v) induced nuclear fragmentation and DNA laddering indicative of apoptosis. Concomitantly, in cells prelabeled with [3H]-serine, ethanol caused a dose-dependent, biphasic increase of the [3H]-ceramide/ [3H]-sphingomyelin ratio after 1 and 18 hours of incubation. As primary alcohols such as ethanol and 1-butanol were shown to inhibit the phospholipase D (PLD)-mediated formation of PA, a mitogenic lipid messenger, we tested their effects on ceramide formation. In astrocytes prelabeled with [3H]-serine, ethanol and 1-butanol, in contrast to t-butanol, significantly increased the formation of [3H]-ceramide. Moreover, exogenous PA, added to transiently permeabilized astrocytes, suppressed ethanol-induced [3H]-ceramide formation. Vice versa, addition of C2-ceramide to astrocytes inhibited PLD activity induced by serum or phorbol ester. Conclusion We propose that the formation of ceramide in ethanol-exposed astrocytes is secondary to the disruption of phospholipase D signaling. Ethanol reduces the PA:ceramide ratio in fetal astrocytes, a mechanism which likely participates in ethanol-induced glial apoptosis during brain development.
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Affiliation(s)
- Beate Schatter
- Department of Pharmacology, School of Medicine, Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Shenchu Jin
- Department of Pharmacology, School of Medicine, Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Konrad Löffelholz
- Department of Pharmacology, School of Medicine, Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Jochen Klein
- Department of Pharmacology, School of Medicine, Johannes Gutenberg University of Mainz, Mainz, Germany
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Science Center, Amarillo, Texas, USA
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24
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Boal F, Zhang H, Tessier C, Scotti P, Lang J. The variable C-terminus of cysteine string proteins modulates exocytosis and protein-protein interactions. Biochemistry 2005; 43:16212-23. [PMID: 15610015 DOI: 10.1021/bi048612+] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cysteine string proteins (Csps) are vesicle proteins involved in neurotransmission and hormone exocytosis. They are composed of distinct domains: a variable N-terminus, a J-domain followed by a linker region, a cysteine-rich string, and a C-terminus which diverges among isoforms. Their precise function and interactions are not fully understood. Using insulin exocytosis as a model, we show that the linker region and the C-terminus, but not the variable N-terminus, regulate overall secretion. Moreover, endogenous Csp1 binds in a calcium-dependent manner to monomeric VAMP2, and this interaction requires the C-terminus of Csp. The interaction is isoform specific as recombinant Csp1 binds VAMP1 and VAMP7, but not VAMP3. Cross-linking in permeabilized clonal beta-cells revealed homodimerization of Csp which is stimulated by Ca(2+) and again modulated by the variant C-terminus. Our data suggest that both interactions of Csp occur during exocytosis and may explain the effect of the variant C-terminus of this chaperon protein on peptide hormone secretion.
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Affiliation(s)
- Frédéric Boal
- Institut Européen de Chimie et Biologie, Pôle Biologie Cellulaire et Moléculaire, JE 2390, 33607 Pessac/Bordeaux, France
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25
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Sarıyar B, Özkan P, Kırdar B, Hortaçsu A. Expression and translocation of glucose isomerase as a fusion protein in E. coli. Enzyme Microb Technol 2004. [DOI: 10.1016/j.enzmictec.2003.10.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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26
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Zitzer A, Westover EJ, Covey DF, Palmer M. Differential interaction of the two cholesterol-dependent, membrane-damaging toxins, streptolysin O and Vibrio cholerae cytolysin, with enantiomeric cholesterol. FEBS Lett 2003; 553:229-31. [PMID: 14572629 DOI: 10.1016/s0014-5793(03)01023-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Membrane cholesterol is essential to the activity of at least two structurally unrelated families of bacterial pore-forming toxins, represented by streptolysin O (SLO) and Vibrio cholerae cytolysin (VCC), respectively. Here, we report that SLO and VCC differ sharply in their interaction with liposome membranes containing enantiomeric cholesterol (ent-cholesterol). VCC had very low activity with ent-cholesterol, which is in line with a stereospecific mode of interaction of this toxin with cholesterol. In contrast, SLO was only slightly less active with ent-cholesterol than with cholesterol, suggesting a rather limited degree of structural specificity in the toxin-cholesterol interaction.
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Affiliation(s)
- Alexander Zitzer
- Department of Hematology and Oncology, Johannes Gutenberg University, D-55101 Mainz, Germany
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27
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Stassen M, Müller C, Richter C, Neudörfl C, Hültner L, Bhakdi S, Walev I, Schmitt E. The streptococcal exotoxin streptolysin O activates mast cells to produce tumor necrosis factor alpha by p38 mitogen-activated protein kinase- and protein kinase C-dependent pathways. Infect Immun 2003; 71:6171-7. [PMID: 14573633 PMCID: PMC219607 DOI: 10.1128/iai.71.11.6171-6177.2003] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptolysin O (SLO), a major virulence factor of pyogenic streptococci, binds to cholesterol in the membranes of eukaryotic cells and oligomerizes to form large transmembrane pores. While high toxin doses are rapidly cytocidal, low doses are tolerated because a limited number of lesions can be resealed. Here, we report that at sublethal doses, SLO activates primary murine bone marrow-derived mast cells to degranulate and to rapidly induce or enhance the production of several cytokine mRNAs, including tumor necrosis factor alpha (TNF-alpha). Mast cell-derived TNF-alpha plays an important protective role in murine models of acute inflammation, and the production of this cytokine was analyzed in more detail. Release of biologically active TNF-alpha peaked approximately 4 h after stimulation with SLO. Production of TNF-alpha was blunted upon depletion of protein kinase C by pretreatment of the cells with phorbol-12 myristate-13 acetate. Transient permeabilization of mast cells with SLO also led to the activation of the stress-activated protein kinases p38 mitogen-activated protein (MAP) kinase and c-jun N-terminal kinase (JNK), and inhibition of p38 MAP kinase markedly reduced production of TNF-alpha. In contrast, secretion of preformed granule constituents triggered by membrane permeabilization was not dependent on p38 MAP kinase or on protein kinase C. Thus, transcriptional activation of mast cells following transient permeabilization might contribute to host defense against infections via the beneficial effects of TNF-alpha. However, hyperstimulation of mast cells might also lead to overproduction of TNF-alpha, which would then promote the development of toxic streptococcal syndromes.
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Affiliation(s)
- Michael Stassen
- Institute of Immunology. Institute of Medical Microbiology, Johannes Gutenberg University, Mainz, Germany
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28
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Höltje M, Winter S, Walther D, Pahner I, Hörtnagl H, Ottersen OP, Bader M, Ahnert-Hilger G. The vesicular monoamine content regulates VMAT2 activity through Galphaq in mouse platelets. Evidence for autoregulation of vesicular transmitter uptake. J Biol Chem 2003; 278:15850-8. [PMID: 12604601 DOI: 10.1074/jbc.m212816200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Variations in the neurotransmitter content of secretory vesicles enable neurons to adapt to network changes. Vesicular content may be modulated by vesicle-associated Go(2), which down-regulates the activity of the vesicular monoamine transmitter transporters VMAT1 in neuroendocrine cells and VMAT2 in neurons. Blood platelets resemble serotonergic neurons with respect to transmitter storage and release. In streptolysin O-permeabilized platelets, VMAT2 activity is also down-regulated by the G protein activator guanosine 5'-(beta(i)gamma-imido)triphosphate (GMppNp). Using serotonin-depleted platelets from peripheral tryptophan hydroxylase knockout (Tph1-/-) mice, we show here that the vesicular filling initiates the G protein-mediated down-regulation of VMAT2 activity. GMppNp did not influence VMAT2 activity in naive platelets from Tph1-/- mice. GMppNp-mediated inhibition could be reconstituted, however, when preloading Tph1-/- platelets with serotonin or noradrenaline. Galpha(q) mediates the down-regulation of VMAT2 activity as revealed from uptake studies performed with platelets from Galpha(q) deletion mutants. Serotonergic, noradrenergic, as well as thromboxane A(2) receptors are not directly involved in the down-regulation of VMAT2 activity. It is concluded that in platelets the vesicle itself regulates transmitter transporter activity via its content and vesicle-associated Galpha(q).
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Affiliation(s)
- Markus Höltje
- Institut für Anatomie der Charité, Humboldt Universität zu Berlin, Philippstrasse 12, 10115 Berlin, Germany
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29
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Abstract
A zone of beta-hemolysis surrounding colonies on blood-agar media is a hallmark phenotypic feature of the pathogens group A Streptococcus (GAS) and group B Streptococcus (GBS). In each case, lysis of red blood cells reflects the action of a potent protein exotoxin. Although these toxins have been the subjects of numerous investigations over the years, their purification and molecular identification have proven elusive. These difficulties reflect the instability of hemolytic activity, as both toxins function only in the context of the bacterial surface or certain high molecular weight 'stabilizer' molecules. This review highlights the recent discoveries of two markedly distinct genetic loci, necessary and sufficient for the beta-hemolytic phenotypes of GAS and GBS, respectively. The generation of isogenic GAS and GBS beta-hemolysin-deficient mutants and their analysis using in vitro and in vivo model systems has shown that both toxins function as virulence factors in the pathogenesis of invasive infections.
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Affiliation(s)
- Victor Nizet
- Division of Pediatric Infectious Diseases, University of California, San Diego, 9500 Gilman Drive, MC 0672, La Jolla 92093, USA.
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30
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Jahn B, Langfelder K, Schneider U, Schindel C, Brakhage AA. PKSP-dependent reduction of phagolysosome fusion and intracellular kill of Aspergillus fumigatus conidia by human monocyte-derived macrophages. Cell Microbiol 2002; 4:793-803. [PMID: 12464010 DOI: 10.1046/j.1462-5822.2002.00228.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previously, we described the isolation of an Aspergillus fumigatus mutant producing non-pigmented conidia, as a result of a defective polyketide synthase gene, pksP (polyketide synthase involved in pigment biosynthesis). The virulence of the pksP mutant was attenuated in a murine animal infection model and its conidia showed enhanced susceptibility towards damage by monocytes in vitro. Because macrophage-mediated killing is critical for host resistance to aspergillosis, the interaction of both grey-green wild-type conidia and white pksP mutant conidia with human monocyte-derived macrophages (MDM) was studied with respect to intracellular processing of ingested conidia. After phagocytosis, the percentage of wild-type conidia residing in an acidic environment was approximately fivefold lower than that observed for non-pigmented pksP mutant conidia. The phagolysosome formation, as assessed by co-localization of LAMP-1 and cathepsin D with ingested conidia, was significantly lower for wild-type conidia compared with pksP mutant conidia. Furthermore, the intracellular kill of pksP mutant conidia was significantly higher than of wild-type conidia, which was markedly increased by chloroquine, a known enhancer of phagolysosome fusion. Taken together, these findings suggest that the presence of a functional pksP gene in A. fumigatus conidia is associated with an inhibition of phagolysosome fusion in human MDM. These data show for the first time that a fungus has the capability to inhibit the fusion of the phagosome with the lysosome. This finding might help explain the attenuated virulence of pksP mutant strains in a murine animal model and provides a conceptual frame to understand the virulence of A. fumigatus.
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Affiliation(s)
- Bernhard Jahn
- Institut für Medizinische Mikrobiologie und Hygiene, Johannes Gutenberg-Universität Mainz, Hochhaus am Augustusplatz, D-55101 Mainz, Germany.
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Walev I, Hombach M, Bobkiewicz W, Fenske D, Bhakdi S, Husmann M. Resealing of large transmembrane pores produced by streptolysin O in nucleated cells is accompanied by NF-kappaB activation and downstream events. FASEB J 2002; 16:237-9. [PMID: 11744625 DOI: 10.1096/fj.01-0572fje] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Streptolysin O (SLO), archetype of a cholesterol-binding bacterial cytolysin, forms large pores in the plasma membrane of mammalian cells. We have recently reported that when a limited number of pores are generated in a cell, they can be sealed in a Ca++-dependent process. Here, we show that resealing is followed by the release of IL-6 and IL-8 from keratinocytes and from endothelial cells, both relevant targets for SLO attack. Production of cytokines by these cells was preceded by activation of transcription factor nuclear factor kappaB, which thus emerges as a common denominator of stress responses to various pore-forming agents, including alpha-toxin of Staphylococcus aureus and complement. Furthermore, we show that activation and cytokine release in response to an agent that forms a pore in the plasma membrane do not depend on paracrine effects, because supernatants of cells perforated by SLO did not activate bystander cells. The study provides definitive evidence that a transient transmembrane pore suffices to trigger productive transcriptional activation in a target cell.
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Affiliation(s)
- Iwan Walev
- Institute of Medical Microbiology, Johannes Gutenberg-University Mainz, D-55101 Mainz, Germany.
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32
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Zitzer A, Bittman R, Verbicky CA, Erukulla RK, Bhakdi S, Weis S, Valeva A, Palmer M. Coupling of cholesterol and cone-shaped lipids in bilayers augments membrane permeabilization by the cholesterol-specific toxins streptolysin O and Vibrio cholerae cytolysin. J Biol Chem 2001; 276:14628-33. [PMID: 11279036 DOI: 10.1074/jbc.m100241200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vibrio cholerae cytolysin (VCC) forms oligomeric pores in lipid bilayers containing cholesterol. Membrane permeabilization is inefficient if the sterol is embedded within bilayers prepared from phosphatidylcholine only but is greatly enhanced if the target membrane also contains ceramide. Although the enhancement of VCC action is stereospecific with respect to cholesterol, we show here that no such specificity applies to the two stereocenters in ceramide; all four stereoisomers of ceramide enhanced VCC activity in cholesterol-containing bilayers. A wide variety of ceramide analogs were as effective as D-erythro-ceramide, as was diacylglycerol, suggesting that the effect of ceramide exemplifies a general trend of lipids with a small headgroup to augment the activity of VCC. Incorporation of these cone-shaped lipids into cholesterol-containing bilayers also gave similar effects with streptolysin O, another cholesterol-specific but structurally unrelated cytolysin. In contrast, the activity of staphylococcal alpha-hemolysin, which does not share with the other toxins the requirement for cholesterol, was far less affected by the presence of lipids with a conical shape. The collective data indicate that sphingolipids and glycerolipids do not interact with the cytolysins specifically. Instead, lipids that have a conical molecular shape appear to effect a change in the energetic state of membrane cholesterol that in turn augments the interaction of the sterol with the cholesterol-specific cytolysins.
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Affiliation(s)
- A Zitzer
- Institute of Medical Microbiology and Hygiene, University of Mainz, Obere Zahlbacher Strasse 67, D55101 Mainz, Germany
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33
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Gut A, Kiraly CE, Fukuda M, Mikoshiba K, Wollheim CB, Lang J. Expression and localisation of synaptotagmin isoforms in endocrine (β)-cells: their function in insulin exocytosis. J Cell Sci 2001; 114:1709-16. [PMID: 11309201 DOI: 10.1242/jcs.114.9.1709] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Exocytosis of insulin containing Large Dense Core Vesicles (LDCVs) from pancreatic (β)-cells and derived cell lines is mainly controlled by Ca(2+). Several lines of evidence have demonstrated a role of the Ca(2+)- and phospholipid-binding protein synaptotagmin (syt) in this event. Synaptotagmins form a large protein family with distinct affinities for Ca(2+) determined by their two C(2) domains (C(2)A/B). Except for the well-characterized isoforms I and II, their role is still unclear. We have used here insulin-secreting cells as a model system for LDCV exocytosis to gain insight into the function of synaptotagmins. Immunocytochemical analysis revealed that of the candidate Ca(2+) sensors in LDCV exocytosis, syt III was not expressed in primary (β)-cells, whereas syt IV was only found adjacent to the TGN. However, syt V-VIII isoforms were expressed at different levels in various insulin-secreting cells and in pancreatic islet preparations. In streptolysin-O permeabilized primary (β)-cells the introduction of recombinant peptides (100 nM) corresponding to the C(2) domains of syt V, VII and VIII, but not of syt III, IV or VI, inhibited Ca(2+)-evoked insulin exocytosis by 30% without altering GTP*S-induced release. Our observations demonstrate that syt III and IV are not involved in the exocytosis of LDCVs from primary (β)-cells whereas V, VII and VIII may mediate Ca(2+)-regulation of exocytosis.
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Affiliation(s)
- A Gut
- Division de Biochimie Clinique, Département de Médecine, Université de Genève, CH-1211 Genève 4, Switzerland
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34
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Walev I, Bhakdi SC, Hofmann F, Djonder N, Valeva A, Aktories K, Bhakdi S. Delivery of proteins into living cells by reversible membrane permeabilization with streptolysin-O. Proc Natl Acad Sci U S A 2001; 98:3185-90. [PMID: 11248053 PMCID: PMC30628 DOI: 10.1073/pnas.051429498] [Citation(s) in RCA: 244] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2000] [Indexed: 11/18/2022] Open
Abstract
The pore-forming toxin streptolysin O (SLO) can be used to reversibly permeabilize adherent and nonadherent cells, allowing delivery of molecules with up to 100 kDa mass to the cytosol. Using FITC-labeled albumin, 10(5)-10(6) molecules were estimated to be entrapped per cell. Repair of toxin lesions depended on Ca(2+)-calmodulin and on intact microtubules, but was not sensitive to actin disruption or to inhibition of protein synthesis. Resealed cells were viable for days and retained the capacity to endocytose and to proliferate. The active domains of large clostridial toxins were introduced into three different cell lines. The domains were derived from Clostridium difficile B-toxin and Clostridium sordelli lethal toxin, which glycosylate small G-proteins, and from Clostridium botulinum C2 toxin, which ADP-ribosylates actin. After delivery with SLO, all three toxins disrupted the actin cytoskeleton to cause rounding up of the cells. Glucosylation assays demonstrated that G-proteins Rho and Ras were retained in the permeabilized cells and were modified by the respective toxins. Inactivation of these G-proteins resulted in reduced stimulus-dependent granule secretion, whereas ADP-ribosylation of actin by the C. botulinum C2-toxin resulted in enhanced secretion in cells. The presented method for introducing proteins into living cells should find multifaceted application in cell biology.
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Affiliation(s)
- I Walev
- Institute of Medical Microbiology and Hygiene, Johannes Gutenberg University, 55101 Mainz, Germany
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35
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Lautenschlager M, Höltje M, von Jagow B, Veh RW, Harms C, Bergk A, Dirnagl U, Ahnert-Hilger G, Hörtnagl H. Serotonin uptake and release mechanisms in developing cultures of rat embryonic raphe neurons: age- and region-specific differences. Neuroscience 2001; 99:519-27. [PMID: 11029543 DOI: 10.1016/s0306-4522(00)00222-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The development of serotonergic neurons of the rat raphe was followed in primary neuronal cell cultures taken at embryonic days embryonic day 13 and embryonic day 14 from three different raphe sub-groups, topographically defined with respect to their position to the isthmus as rostral (R1), intermediate (R2) and caudal (R3). In neurons cultivated from embryonic day 13 raphe serotonin, immunoreactivity was detected after only two days in vitro in the rostral R1 and the intermediate R2 sub-groups. Within two weeks of cultivation the number of serotonergic neurons as well as the dendritic branching continuously increased in all three sub-groups. In cultures obtained from embryonic day 13 raphe a specific uptake of [3H]serotonin could not be detected during the first days in vitro. Specific uptake as well as regulated serotonin release, however, was clearly discernible in these cultures after nine days in vitro, indicating developmental differentiation of the initially immature serotonergic neurons in culture. In contrast, serotonergic neurons obtained from the three raphe sub-groups at embryonic day 14 took up and released [3H]serotonin, as early as after two days in culture. Basal as well as stimulated serotonin release was diminished when preincubating the cells with tetanus toxin, which cleaves synaptobrevin thereby blocking exocytosis. Our data indicate that the differential development of serotonergic neurons in the various raphe sub-groups in vivo is also sustained in culture. The differences observed when comparing neurons from embryonic days 13 and 14 suggest that a short time-period of about 24h appears to be crucial for the developmental upregulation of serotonin uptake, storage and release.
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Affiliation(s)
- M Lautenschlager
- Institute of Pharmacology and Toxicology, Medical Faculty Charité, Humboldt-University at Berlin, D-10098, Berlin, Germany
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36
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Weis S, Palmer M. Streptolysin O: the C-terminal, tryptophan-rich domain carries functional sites for both membrane binding and self-interaction but not for stable oligomerization. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1510:292-9. [PMID: 11342166 DOI: 10.1016/s0005-2736(00)00360-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Streptolysin O belongs to the class of thiol-activated toxins, which are single chain, four-domain proteins that bind to membranes containing cholesterol and then assemble to form large oligomeric pores. Membrane binding involves a conserved tryptophan-rich sequence motif located within the C-terminally located domain 4. In contrast, sites involved in oligomerization and pore formation have been assigned to domains 1 and 3, respectively. We here examined the functional properties of domain 4, which was recombinantly expressed with an N-terminal histidine tag for purification and an additional cysteine residue for covalent labeling. The fluorescently labeled fragment readily bound to membranes, but it did not form oligomers nor lyse cell membranes. Moreover, the labeled fragment did not detectably become incorporated into hybrid oligomers when combined with lytically active full-length toxin. However, when present in large excess over the active toxin, the domain 4 fragment effected reduction of hemolytic activity and of functional pore size, which indicates interference with oligomerization of the lytically active species. Our findings support the notion that domain 4 of the streptolysin O molecule may fold autonomously, is essential for membrane binding and is capable not of irreversible but of reversible association with the entire toxin molecule.
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Affiliation(s)
- S Weis
- Institute of Medical Microbiology, University of Mainz, Augustusplatz, 55101 Mainz, Germany
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37
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Baumeister S, Paprotka K, Bhakdi S, Lingelbach K. Selective permeabilization of infected host cells with pore-forming proteins provides a novel tool to study protein synthesis and viability of the intracellular apicomplexan parasites Plasmodium falciparum and Toxoplasma gondii. Mol Biochem Parasitol 2001; 112:133-7. [PMID: 11166394 DOI: 10.1016/s0166-6851(00)00343-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- S Baumeister
- FB Biologie/Zoologie, Philipps Universität Marburg, 35032 Marburg, Germany
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38
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Walev I, Tappe D, Gulbins E, Bhakdi S. Streptolysin O‐permeabilized granulocytes shed L‐selectin concomitantly with ceramide generation via neutral sphingomyelinase. J Leukoc Biol 2000. [DOI: 10.1189/jlb.68.6.865] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Iwan Walev
- Institute of Medical Microbiology and Hygiene, University of Mainz, Germany
- Institute of Physiology I, University of Tuebingen, Germany
| | - Dennis Tappe
- Institute of Medical Microbiology and Hygiene, University of Mainz, Germany
- Institute of Physiology I, University of Tuebingen, Germany
| | - Erich Gulbins
- Institute of Physiology I, University of Tuebingen, Germany
| | - Sucharit Bhakdi
- Institute of Medical Microbiology and Hygiene, University of Mainz, Germany
- Institute of Physiology I, University of Tuebingen, Germany
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39
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Gonelle-Gispert C, Molinete M, Halban PA, Sadoul K. Membrane localization and biological activity of SNAP-25 cysteine mutants in insulin-secreting cells. J Cell Sci 2000; 113 ( Pt 18):3197-205. [PMID: 10954418 DOI: 10.1242/jcs.113.18.3197] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The tSNARE SNAP-25 is expressed in pancreatic (beta)-cells and is involved in the regulated release of insulin. It has been shown previously that SNAP-25 associates with the plasma membrane consequent to palmitoylation of one or more cysteines in the central region of the molecule. The importance of palmitolyation in the biological function of SNAP-25 in exocytosis was not addressed. Furthermore, studies on both SNAP-25 and its non-palmitoylated homologues SNAP-29 and sec9, have suggested an alternative or complementary mechanism for membrane association involving interaction with syntaxin. To address these issues, we have now studied the behavior and biological activity of cysteine mutant SNAP-25 in insulin-secreting (HIT) cells. While 91% of native SNAP-25 was associated with the membrane, this value decreased to 56% for the single cysteine mutant C85/A and to 10% for the double (C85,88/A) and quadruple (C85,88,90,92/A) mutants. The mutant SNAP-25 forms were all found to bind syntaxin 1A with equal efficacy. Over-expression of syntaxin 1A in HIT cells allowed for partial relocalization of both the double and quadruple SNAP-25 cys mutants to the membrane. By introducing a further mutation to the SNAP-25 molecules to render them resistant to botulinum neurotoxin E, it was possible to study their ability to reconstitute regulated insulin secretion in toxin-treated HIT cells. Native SNAP-25 was able to fully reconstitute secretory activity in such cells. Despite the fact that the single cysteine mutant was significantly displaced to the cytosol, it still displayed 82% activity in the secretion reconstitution assay, and a similar discrepancy was seen for the double mutant. Even the quadruple mutant with no remaining cysteines was able to support a minimal level of secretion. It is concluded that both palmitoylation and binding to syntaxin are implicated in membrane association of SNAP-25. This as well as the discrepancy between membrane localization and biological activity of the cysteine mutants, suggests a complex, multi-component process for association of SNAP-25 with the membrane and its recruitment to a biologically productive state.
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Affiliation(s)
- C Gonelle-Gispert
- Louis-Jeantet Research Laboratories, University Medical Center, 1211 Geneva 4, Switzerland.
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40
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Abstract
Monoamines such as noradrenaline and serotonin are stored in secretory vesicles and released by exocytosis. Two related monoamine transporters, VMAT1 and VMAT2, mediate vesicular transmitter uptake. Previously we have reported that in the rat pheochromocytoma cell line PC 12 VMAT1, localized to peptide-containing secretory granules, is controlled by the heterotrimeric G-protein Go(2). We now show that in BON cells, a human serotonergic neuroendocrine cell line derived from a pancreatic tumor expressing both transporters on large, dense-core vesicles, VMAT2 is even more sensitive to G-protein regulation than VMAT1. The activity of both transporters is only downregulated by Galphao(2), whereas comparable concentrations of Galphao(1) are without effect. In serotonergic raphe neurons in primary culture VMAT2 is also downregulated by pertussis toxin-sensitive Go(2). By electron microscopic analysis from prefrontal cortex we show that VMAT2 and Galphao(2) associate preferentially to locally recycling small synaptic vesicles in serotonergic terminals. In addition, Go(2)-dependent modulation of VMAT2 also works when using a crude synaptic vesicle preparation from this brain area. We conclude that regulation of monoamine uptake by the heterotrimeric G proteins is a general feature of monoaminergic neurons that controls the content of both large, dense-core and small synaptic vesicles.
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41
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Abdel Ghani EM, Weis S, Walev I, Kehoe M, Bhakdi S, Palmer M. Streptolysin O: inhibition of the conformational change during membrane binding of the monomer prevents oligomerization and pore formation. Biochemistry 1999; 38:15204-11. [PMID: 10563803 DOI: 10.1021/bi991678y] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Streptolysin O is a four-domain protein toxin that permeabilizes animal cell membranes. The toxin first binds as a monomer to membrane cholesterol and subsequently assembles into oligomeric transmembrane pores. Binding is mediated by a C-terminally located tryptophan-rich motif. In a previous study, conformational effects of membrane binding were characterized by introducing single mutant cysteine residues that were then thiol-specifically derivatized with the environmentally sensitive fluorophoracrylodan. Membrane binding of the labeled proteins was accompanied by spectral shifts of the probe fluorescence, suggesting that the toxin molecule had undergone a conformational change. Here we provide evidence that this change corresponds to an allosteric transition of the toxin monomer that is required for the subsequent oligomerization and pore formation. The conformational change is reversible with reversal of binding, and it is related to temperature in a fashion that closely parallels the temperature-dependency of oligomerization. Furthermore, we describe a point mutation (N402E) that, while compatible with membrane binding, abrogates the accompanying conformational change. At the same time, the N402E mutation also abolishes oligomerization. These findings corroborate the contention that the target membrane acts as an allosteric effector to activate the oligomerizing and pore-forming capability of streptolysin O.
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Affiliation(s)
- E M Abdel Ghani
- Institute of Medical Microbiology, University of Mainz, Germany
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42
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Sun J, Bird CH, Buzza MS, McKee KE, Whisstock JC, Bird PI. Expression and purification of recombinant human granzyme B from Pichia pastoris. Biochem Biophys Res Commun 1999; 261:251-5. [PMID: 10425174 DOI: 10.1006/bbrc.1999.0989] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Granzyme B is a cytotoxic lymphocyte granule serine proteinase that is pivotal in the induction of target cell apoptosis. Here we describe the expression of recombinant human granzyme B in Pichia pastoris as a chimeric zymogen comprising the alpha-factor signal sequence, a prodomain including an enterokinase cleavage site, and the mature granzyme B sequence followed by a hexahistidine tag. Inactive zymogen is purified from the medium by immobilized cobalt chelate affinity chromatography and then activated by enterokinase (final yield is approximately 1 mg per liter). The recombinant enzyme resembles native granzyme B in size and glycosylation, hydrolyzes the substrate Boc-Ala-Ala-Asp-thiobenzyl ester with equivalent efficiency (K(m) 82 microM; k(cat) 12 s(-1)), processes procaspase-3 to subunit form, and is inhibited by the cognate serpin PI-9. It efficiently induces DNA degradation and apoptosis of human cells. The availability of recombinant human granzyme B will facilitate further investigation of its structure and role in immune effector cells.
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Affiliation(s)
- J Sun
- Monash Medical School, Box Hill Hospital, Australia
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43
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Zhang H, Kelley WL, Chamberlain LH, Burgoyne RD, Lang J. Mutational analysis of cysteine-string protein function in insulin exocytosis. J Cell Sci 1999; 112 ( Pt 9):1345-51. [PMID: 10194413 DOI: 10.1242/jcs.112.9.1345] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cysteine-string proteins (Csps) are vesicle proteins involved in neurotransmission. They contain at least four domains: an N-terminal J-domain which can interact with the chaperone Hsc70, an adjacent linker region, the defining cysteine rich domain and a variable C terminus. As the relevance of these domains for the function of Csps in exocytosis is unknown, we have performed a mutational analysis of Csp domains using insulin release by large dense core vesicles (LDCVs) as a model of regulated exocytosis. All mutants were apparently palmitoylated and their subcellular distribution was similar to endogenous Csp. Point mutations within the highly conserved HPD motif of the J-domain abolished activation of Hsc70. However, these mutations altered the effect of Csp on exocytosis only after additional truncation of the extreme C terminus as found in the Csp splice variant Csp2. Furthermore, the strikingly conserved linker region adjacent to the J-domain was important for Csp function in exocytosis, but not for the activation of Hsc70 ATPase. The effects of Csp wild-type or mutants were preserved in permeabilized cells excluding an effect on transmembrane ion fluxes. These observations demonstrate a functional difference between the two isoforms and suggest a role for the J-domain co-chaperone function as well as for the newly defined linker region in LDCV exocytosis.
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Affiliation(s)
- H Zhang
- Division de Biochimie Clinique, Département de Médecine Interne, and Département de Biochemie Médicale, Centre Médicale Universitaire, CH 1211 Genève 4, Switzerland
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44
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Zhang H, Kelley WL, Chamberlain LH, Burgoyne RD, Wollheim CB, Lang J. Cysteine-string proteins regulate exocytosis of insulin independent from transmembrane ion fluxes. FEBS Lett 1998; 437:267-72. [PMID: 9824305 DOI: 10.1016/s0014-5793(98)01233-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Cysteine-string proteins (Csps) are vesicle proteins involved in exocytosis of synaptic vesicles in Drosophila and modulation of presynaptic calcium influx. As both the contribution of calcium channel regulation to the role of Csp in exocytosis and a function of Csp outside the nervous system are unknown, we studied its function in endocrine exocytosis from large dense core vesicles (LDCVs) using insulin-secreting pancreatic beta-cells. Csps were expressed in primary and derived beta-cell lines on insulin-containing LDCVs. Suppression of Csp expression reduced not only depolarisation induced insulin release but also exocytosis in permeabilised cells directly stimulated by Ca2+. Thus, Csp is a secretory granule protein and is required for endocrine exocytosis independent of the modulation of transmembrane calcium fluxes.
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Affiliation(s)
- H Zhang
- Département de Médecine Interne, Centre Médical Universitaire, Genève, Switzerland
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45
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Ohyama H, Matsushita S, Kato N, Nishimura F, Oyaizu K, Kokeguchi S, Kurihara H, Takashiba S, Nishimura Y, Murayama Y. T cell responses to 53-kDa outer membrane protein of Porphyromonas gingivalis in humans with early-onset periodontitis. Hum Immunol 1998; 59:635-43. [PMID: 9757945 DOI: 10.1016/s0198-8859(98)00064-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Patients with early-onset periodontitis (EOP) are susceptible to infection with periodontopathic bacteria, such as Porphyromonas gingivalis. Ag53, 53-kDa outer membrane protein of P. gingivalis, evokes strong humoral immune responses in EOP patients. In a first step to clarify how host immune cells recognize Ag53, we established Ag53-specific short-term T cell lines from 22 subjects including 6 EOP patients and 16 healthy donors, using overlapping peptides based on Ag53 amino acid sequences. All T cell lines from active EOP patients recognized a common region (p141-181, especially p141-161) on Ag53, while those from healthy donors showed heterogeneous specificity. p141-181 was not recognized by T cell lines established from EOP patients following therapy. A monoclonal antibody to HLA-DRB 1 inhibited Ag53-induced proliferation of most of the T cell lines. Our observations suggest that, although antigen-presenting molecules are common in EOP patients and in healthy individuals, p141-161 includes a major T cell epitope(s) on Ag53 for active EOP patients but not for healthy individuals or inactive EOP patients.
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Affiliation(s)
- H Ohyama
- Department of Periodontology and Endodontology, Okayama University Dental School, Japan
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46
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Jahn B, Rampp A, Dick C, Jahn A, Palmer M, Bhakdi S. Accumulation of amphotericin B in human macrophages enhances activity against Aspergillus fumigatus conidia: quantification of conidial kill at the single-cell level. Antimicrob Agents Chemother 1998; 42:2569-75. [PMID: 9756757 PMCID: PMC105899 DOI: 10.1128/aac.42.10.2569] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A cytofluorometric assay that allowed assessment of damage to phagocytosed Aspergillus fumigatus conidia at the single-cell level was developed. After ingestion by monocyte-derived macrophages (MDMs), conidia were reisolated by treatment of the cells with streptolysin O, a pore-forming toxin with lytic properties on mammalian cells but not on fungi. The counts obtained by staining of damaged conidia with propidium iodide and quantification by cytofluorometry correlated with colony counts. By the use of this method, we demonstrate that MDMs differentiated in vitro by low-dose granulocyte-macrophage colony-stimulating factor and gamma interferon have only a limited capacity to damage Aspergillus conidia in vitro. The killing rate 12 h after phagocytosis was found to be only 10 to 15%. However, intracellular loading of the phagocytes with amphotericin B (AmB) dose dependently enhanced the anticonidial activity. Preincubation of macrophages with only 1 microg of AmB per ml resulted in an uptake of 18 fg of AmB/cell, leading to killing rates of 50 to 60%. The experimental protocol provides a new tool for the rapid quantification of anticonidial activity against A. fumigatus in vitro. Intracellular accumulation of AmB may represent an important factor underlying the efficacy of this antifungal drug in the prophylaxis and treatment of Aspergillus infections.
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Affiliation(s)
- B Jahn
- Institute of Medical Microbiology and Hygiene, Johannes Gutenberg University, Mainz, Mainz, Germany.
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47
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Harris JR, Adrian M, Bhakdi S, Palmer M. Cholesterol-Streptolysin O Interaction: An EM Study of Wild-Type and Mutant Streptolysin O. J Struct Biol 1998; 121:343-55. [PMID: 9705878 DOI: 10.1006/jsbi.1998.3989] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We present transmission electron microscopical data from negatively stained specimens of cholesterol following interaction with the thiol-activated bacterial toxin streptolysin O (SLO) (wild-type and a number of cysteine substitution mutants), with and without chemical modification of the cysteine residues. Two experimental systems were used, one with an aqueous suspension of cholesterol microcrystals and the other with immobilized thin planar cholesterol crystals attached to a carbon film. In both systems the wild-type SLO and two cytolytically active mutants, Cys 530 --> Ala (C530A) and Ser 101 --> Cys (S101C), readily generated the characteristic SLO arc- and ring-like oligomers on the surface of cholesterol microcrystals and immobilized planar cholesterol crystals. An underlying array of bound toxin can sometimes be detected. In the presence of high concentrations of SLO monomer, extensive sheet-like networks of linked oligomers extend from the microcrystals. The SLO mutant Thr250 --> Cys (T250C), which also possesses a relatively high cytolytic activity, has been found to create ring-like toxin oligomers somewhat more slowly than wild-type SLO, but the linear monomolecular layer array of cholesterol-bound toxin is more readily detected. With mutant Asn402 --> Cys (N402C), which has approximately 10% cytolytic activity compared to wild-type SLO, the formation of ring-like oligomers is markedly reduced, with incomplete arcs and the parallel arrays predominating. Chemical modification of the functional cysteine groups of SLO mutants T250C and N402C completely inhibits the formation of toxin oligomers, but does not prevent the ability of these mutants to bind to cholesterol as a linear array. Such chemical modification is also known to abolish hemolysis/cytolysis. For both mutant T250C and N402C the parallel array of bound SLO adopts an orientation that appears to be determined by the underlying lattice of the crystalline cholesterol. The cholesterol-binding of biotinylated SLO mutant N402C was confirmed by labeling in suspension with 5-nm streptavidin-conjugated colloidal gold particles. Removal of the maltose-binding protein from the SLO fusion products increases the order of the monolayer array of biotinylated SLO bound to cholesterol crystals. Overall, our data support the concept that there is sterospecific binding of the SLO monomer to crystalline cholesterol bilayers, prior to oligomer formation. With the mutants tested, cysteine modification does not prevent binding to cholesterol, but subsequent release and oligomer formation are blocked. Copyright 1998 Academic Press.
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Affiliation(s)
- JR Harris
- Institute of Zoology, University of Mainz, Mainz, D-55099, Germany
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Palmer M, Harris R, Freytag C, Kehoe M, Tranum-Jensen J, Bhakdi S. Assembly mechanism of the oligomeric streptolysin O pore: the early membrane lesion is lined by a free edge of the lipid membrane and is extended gradually during oligomerization. EMBO J 1998; 17:1598-605. [PMID: 9501081 PMCID: PMC1170507 DOI: 10.1093/emboj/17.6.1598] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Streptolysin O (SLO) is a bacterial exotoxin that binds to cell membranes containing cholesterol and then oligomerizes to form large pores. Along with rings, arc-shaped oligomers form on membranes. It has been suggested that each arc represents an incompletely assembled oligomer and constitutes a functional pore, faced on the opposite side by a free edge of the lipid membrane. We sought functional evidence in support of this idea by using an oligomerization-deficient, non-lytic mutant of SLO. This protein, which was created by chemical modification of a single mutant cysteine (T250C) with N-(iodoacetaminoethyl)-1-naphthylamine-5-sulfonic acid, formed hybrid oligomers with active SLO on membranes. However, incorporation of the modified T250C mutant inhibited subsequent oligomerization, so that the hybrid oligomers were reduced in size. These appeared as typical arc lesions in the electron microscope. They formed pores that permitted passage of NaCl and calcein but restricted permeation of large dextran molecules. The data indicate that the SLO pore is formed gradually during oligomerization, implying that pores lined by protein on one side and an edge of free lipid on the other may be created in the plasma membrane. Intentional manipulation of the pore size may extend the utility of SLO as a tool in cell biological experiments.
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Affiliation(s)
- M Palmer
- Institute of Medical Microbiology, University of Mainz, Augustusplatz, D-55101 Mainz, Germany
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Palmer M, Vulicevic I, Saweljew P, Valeva A, Kehoe M, Bhakdi S. Streptolysin O: a proposed model of allosteric interaction between a pore-forming protein and its target lipid bilayer. Biochemistry 1998; 37:2378-83. [PMID: 9485385 DOI: 10.1021/bi9720890] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Streptolysin O, a polypeptide of 571 amino acids, belongs to the family of thiol-activated toxins that permeabilize animal cell membranes. The protein binds as a monomer to membrane cholesterol. Binding involves a conserved region close to the C-terminus and triggers subsequent polymerization into large arc- and ring-shaped structures surrounding pores of up to 30 nm. Besides the C-terminus, a distantly located region spanning residues 213-305 is involved in oligomerization and in membrane insertion. Here, we searched for conformational effects of monomer binding to the latter functionally important region. To this end, single cysteine substitution mutants were produced and derivatized with the polarity-sensitive fluorophore acrylodan. Fluorimetric measurements revealed that binding of the monomer to membranes is accompanied by distinct environmental changes at amino acid residues 218, 248, 266, and 277. Conspicuously, the environment of residues 218 and 266 became more hydrophilic, suggesting movement of these residues out of hydrophobic protein pockets. Upon oligomerization, further alterations in all side-chain environments were observed. The membrane-bound monomer thus differs in conformation from both the monomer in solution and the subunit of the oligomer. The putative binding site of the molecule is linked to remote domains involved in oligomerization and membrane insertion in an apparently allosteric fashion. It is proposed that allostery is responsible for restricting oligomerization to the membrane-bound state of the toxin.
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Affiliation(s)
- M Palmer
- Institute of Medical Microbiology, University of Mainz, Augustusplatz, D55101 Germany
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Florova G, Denoya CD, Morgenstern MR, Skinner DD, Reynolds KA. Cloning, expression, and characterization of a type II 3-dehydroquinate dehydratase gene from Streptomyces hygroscopicus. Arch Biochem Biophys 1998; 350:298-306. [PMID: 9473305 DOI: 10.1006/abbi.1997.0536] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A gene encoding dehydroquinate dehydratase (DHQase) was cloned from Streptomyces hygroscopicus var. ascomyceticus. The 528-bp open reading frame specified a primary translation product of 175 amino acids with a calculated Mr of 18,789. The predicted amino acid sequence of the DHQase showed similarities to bacterial and fungal type II DHQases. Overexpression of the dhq gene was accomplished in Escherichia coli using a gene fusion technique in which a malE, the gene encoding the maltose binding protein (MBP), was fused via a short oligonucleotide region to the beginning of dhq. The recombinant MBP-DHQase fusion protein was purified by affinity chromatography and cleaved using thrombin. The resulting DHQase, separated from the MBP, demonstrated typical properties of a type II DHQase: a relatively high Km for the dehydroquinate substrate (650 microM) and extreme thermal stability. The subunit Mr estimated by SDS-PAGE was 19,000, and the native Mr estimated by gel-exclusion chromatography and sucrose-density centrifugation was 130,000, suggesting that the enzyme is a homoheptamer (type II DHQases are typically homododecamers). The MBP-DHQase complex also adopted a heptameric structure and was a thermostable, fully active DHQase, indicating that the N-terminus is not involved in formation of protomer-protomer complexes. Previous analyses have supported positioning the N-terminus of type II DHQases close to the active site and a conformational change in this region coincident with ligand binding. Nonetheless, the Km and relative kcat obtained for MBP-DHQase were indistinguishable from those observed for DHQase. Inactivation data of the DHQase from S. hygroscopicus with the arginine-specific reagent phenylglyoxal showed that a modified Arg residue(s) is likely close to the N-terminus and active site of DHQase, but does not play an essential role in catalysis.
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Affiliation(s)
- G Florova
- School of Pharmacy and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia 23219, USA
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