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Harper M, Wright A, St Michael F, Li J, Deveson Lucas D, Ford M, Adler B, Cox AD, Boyce JD. Characterization of Two Novel Lipopolysaccharide Phosphoethanolamine Transferases in Pasteurella multocida and Their Role in Resistance to Cathelicidin-2. Infect Immun 2017; 85:e00557-17. [PMID: 28874446 PMCID: PMC5649011 DOI: 10.1128/iai.00557-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 08/29/2017] [Indexed: 12/16/2022] Open
Abstract
The lipopolysaccharide (LPS) produced by the Gram-negative bacterial pathogen Pasteurella multocida has phosphoethanolamine (PEtn) residues attached to lipid A, 3-deoxy-d-manno-octulosonic acid (Kdo), heptose, and galactose. In this report, we show that PEtn is transferred to lipid A by the P. multocida EptA homologue, PetL, and is transferred to galactose by a novel PEtn transferase that is unique to P. multocida called PetG. Transcriptomic analyses indicated that petL expression was positively regulated by the global regulator Fis and negatively regulated by an Hfq-dependent small RNA. Importantly, we have identified a novel PEtn transferase called PetK that is responsible for PEtn addition to the single Kdo molecule (Kdo1), directly linked to lipid A in the P. multocida glycoform A LPS. In vitro assays showed that the presence of a functional petL and petK, and therefore the presence of PEtn on lipid A and Kdo1, was essential for resistance to the cationic, antimicrobial peptide cathelicidin-2. The importance of PEtn on Kdo1 and the identification of the transferase responsible for this addition have not previously been shown. Phylogenetic analysis revealed that PetK is the first representative of a new family of predicted PEtn transferases. The PetK family consists of uncharacterized proteins from a range of Gram-negative bacteria that produce LPS glycoforms with only one Kdo molecule, including pathogenic species within the genera Vibrio, Bordetella, and Haemophilus We predict that many of these bacteria will require the addition of PEtn to Kdo for maximum protection against host antimicrobial peptides.
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Affiliation(s)
- Marina Harper
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC, Australia
| | - Amy Wright
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC, Australia
| | - Frank St Michael
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON, Canada
| | - Jianjun Li
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON, Canada
| | - Deanna Deveson Lucas
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC, Australia
| | - Mark Ford
- CSIRO Australian Animal Health Laboratory, Geelong, VIC, Australia
| | - Ben Adler
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC, Australia
| | - Andrew D Cox
- Vaccine Program, Human Health Therapeutics Portfolio, National Research Council, Ottawa, ON, Canada
| | - John D Boyce
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC, Australia
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Tabashnik BE, Zhang M, Fabrick JA, Wu Y, Gao M, Huang F, Wei J, Zhang J, Yelich A, Unnithan GC, Bravo A, Soberón M, Carrière Y, Li X. Dual mode of action of Bt proteins: protoxin efficacy against resistant insects. Sci Rep 2015; 5:15107. [PMID: 26455902 PMCID: PMC4601037 DOI: 10.1038/srep15107] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 09/16/2015] [Indexed: 01/06/2023] Open
Abstract
Transgenic crops that produce Bacillus thuringiensis (Bt) proteins for pest control are grown extensively, but insect adaptation can reduce their effectiveness. Established mode of action models assert that Bt proteins Cry1Ab and Cry1Ac are produced as inactive protoxins that require conversion to a smaller activated form to exert toxicity. However, contrary to this widely accepted paradigm, we report evidence from seven resistant strains of three major crop pests showing that Cry1Ab and Cry1Ac protoxins were generally more potent than the corresponding activated toxins. Moreover, resistance was higher to activated toxins than protoxins in eight of nine cases evaluated in this study. These data and previously reported results support a new model in which protoxins and activated toxins kill insects via different pathways. Recognizing that protoxins can be more potent than activated toxins against resistant insects may help to enhance and sustain the efficacy of transgenic Bt crops.
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Affiliation(s)
| | - Min Zhang
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Jeffrey A. Fabrick
- U.S. Department of Agriculture, Agricultural Research Service, U.S. Arid Land Agricultural Research Center, Maricopa, AZ 85138, USA
| | - Yidong Wu
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Meijing Gao
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA
| | - Jizhen Wei
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100026, China
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100026, China
| | - Alexander Yelich
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | | | - Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62250, Morelos, Mexico
| | - Mario Soberón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62250, Morelos, Mexico
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
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Rumah KR, Ma Y, Linden JR, Oo ML, Anrather J, Schaeren-Wiemers N, Alonso MA, Fischetti VA, McClain MS, Vartanian T. The Myelin and Lymphocyte Protein MAL Is Required for Binding and Activity of Clostridium perfringens ε-Toxin. PLoS Pathog 2015; 11:e1004896. [PMID: 25993478 PMCID: PMC4439126 DOI: 10.1371/journal.ppat.1004896] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 04/19/2015] [Indexed: 12/18/2022] Open
Abstract
Clostridium perfringens ε-toxin (ETX) is a potent pore-forming toxin responsible for a central nervous system (CNS) disease in ruminant animals with characteristics of blood-brain barrier (BBB) dysfunction and white matter injury. ETX has been proposed as a potential causative agent for Multiple Sclerosis (MS), a human disease that begins with BBB breakdown and injury to myelin forming cells of the CNS. The receptor for ETX is unknown. Here we show that both binding of ETX to mammalian cells and cytotoxicity requires the tetraspan proteolipid Myelin and Lymphocyte protein (MAL). While native Chinese Hamster Ovary (CHO) cells are resistant to ETX, exogenous expression of MAL in CHO cells confers both ETX binding and susceptibility to ETX-mediated cell death. Cells expressing rat MAL are ~100 times more sensitive to ETX than cells expressing similar levels of human MAL. Insertion of the FLAG sequence into the second extracellular loop of MAL abolishes ETX binding and cytotoxicity. ETX is known to bind specifically and with high affinity to intestinal epithelium, renal tubules, brain endothelial cells and myelin. We identify specific binding of ETX to these structures and additionally show binding to retinal microvasculature and the squamous epithelial cells of the sclera in wild-type mice. In contrast, there is a complete absence of ETX binding to tissues from MAL knockout (MAL-/-) mice. Furthermore, MAL-/- mice exhibit complete resistance to ETX at doses in excess of 1000 times the symptomatic dose for wild-type mice. We conclude that MAL is required for both ETX binding and cytotoxicity.
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Affiliation(s)
- Kareem Rashid Rumah
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
- Laboratory of Bacterial Pathogenesis and Immunology, The Rockefeller University, New York City, New York, United States of America
| | - Yinghua Ma
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Jennifer R. Linden
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Myat Lin Oo
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Josef Anrather
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
| | - Nicole Schaeren-Wiemers
- Neurobiology, Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Miguel A. Alonso
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, Madrid, Spain
| | - Vincent A. Fischetti
- Laboratory of Bacterial Pathogenesis and Immunology, The Rockefeller University, New York City, New York, United States of America
| | - Mark S. McClain
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Timothy Vartanian
- Brain and Mind Research Institute, Weill Cornell Medical College, New York City, New York, United States of America
- * E-mail:
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Shikano I, Cory JS. Genetic resistance to Bacillus thuringiensis alters feeding behaviour in the cabbage looper, Trichoplusia ni. PLoS One 2014; 9:e85709. [PMID: 24465656 PMCID: PMC3897465 DOI: 10.1371/journal.pone.0085709] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 11/30/2013] [Indexed: 01/16/2023] Open
Abstract
Evolved resistance to xenobiotics and parasites is often associated with fitness costs when the selection pressure is absent. Resistance to the widely used microbial insecticide Bacillus thuringiensis (Bt) has evolved in several insect species through the modification of insect midgut binding sites for Bt toxins, and reports of costs associated with Bt resistance are common. Studies on the costs of Bt-resistance restrict the insect to a single artificial diet or host-plant. However, it is well documented that insects can self-select appropriate proportions of multiple nutritionally unbalanced foods to optimize life-history traits. Therefore, we examined whether Bt-resistant and susceptible cabbage loopers Trichoplusia ni differed in their nutrient intake and fitness costs when they were allowed to compose their own protein:carbohydrate diet. We found that Bt-resistant T. ni composed a higher ratio of protein to carbohydrate than susceptible T. ni. Bt-resistant males exhibited no fitness cost, while the fitness cost (reduced pupal weight) was present in resistant females. The absence of the fitness cost in resistant males was associated with increased carbohydrate consumption compared to females. We demonstrate a sex difference in a fitness cost and a new behavioural outcome associated with Bt resistance.
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Affiliation(s)
- Ikkei Shikano
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail:
| | - Jenny S. Cory
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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Defferrari MS, Demartini DR, Marcelino TB, Pinto PM, Carlini CR. Insecticidal effect of Canavalia ensiformis major urease on nymphs of the milkweed bug Oncopeltus fasciatus and characterization of digestive peptidases. Insect Biochem Mol Biol 2011; 41:388-399. [PMID: 21377528 DOI: 10.1016/j.ibmb.2011.02.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 01/29/2011] [Accepted: 02/24/2011] [Indexed: 05/30/2023]
Abstract
Jackbean (Canavalia ensiformis) ureases are entomotoxic upon the release of internal peptides by insect's digestive enzymes. Here we studied the digestive peptidases of Oncopeltus fasciatus (milkweed bug) and its susceptibility to jackbean urease (JBU). O. fasciatus nymphs fed urease showed a mortality rate higher than 80% after two weeks. Homogenates of midguts dissected from fourth instars were used to perform proteolytic activity assays. The homogenates hydrolyzed JBU in vitro, yielding a fragment similar in size to known entomotoxic peptides. The major proteolytic activity at pH 4.0 upon protein substrates was blocked by specific inhibitors of aspartic and cysteine peptidases, but not significantly affected by inhibitors of metallopeptidases or serine peptidases. The optimal activity upon N-Cbz-Phe-Arg-MCA was at pH 5.0, with complete blockage by E-64 in all pH tested. Optimal activity upon Abz-AIAFFSRQ-EDDnp (a substrate for aspartic peptidases) was detected at pH 5.0, with partial inhibition by Pepstatin A in the pH range 2-8. Fluorogenic substrates corresponding to the N- and C-terminal regions flanking a known entomotoxic peptide within urease sequence were also tested. While the midgut homogenate did not hydrolyze the N-terminal peptide, it cleaved the C-terminal peptide maximally at pH 4.0-5.0, and this activity was inhibited by E-64 (10 μM). The midgut homogenate was submitted to ion-exchange chromatography followed by gel filtration. A 22 kDa active fraction was obtained, resolved in SDS-PAGE (12%), the corresponding band was in-gel digested by trypsin, the peptides were analyzed by mass spectrometry, retrieving a cathepsin L protein. The purified cathepsin L was shown to have at least two possible cleavage sites within the urease sequence, and might be able to release a known insecticidal peptide in a single or cascade event. The results suggest that susceptibility of O. fasciatus nymphs to jackbean urease is, like in other insect models, due mostly to limited proteolysis of ingested protein and subsequent release of entomotoxic peptide(s) by cathepsin-like digestive enzymes.
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Affiliation(s)
- Marina S Defferrari
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, CEP 91501-970 Porto Alegre, Rio Grande do Sul, Brazil
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Sikand P, Dong X, LaMotte RH. BAM8-22 peptide produces itch and nociceptive sensations in humans independent of histamine release. J Neurosci 2011; 31:7563-7. [PMID: 21593341 PMCID: PMC3111068 DOI: 10.1523/jneurosci.1192-11.2011] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 04/04/2011] [Accepted: 04/11/2011] [Indexed: 11/21/2022] Open
Abstract
Chronic itch accompanying many dermatological, neurological, and systemic diseases is unresponsive to antihistamines. Our knowledge of endogenous chemicals that evoke histamine-independent itch and their molecular targets is very limited. Recently it was demonstrated in behavioral and cellular experiments that bovine adrenal medulla 8-22 peptide (BAM8-22), a proteolytically cleaved product of proenkephalin A, is a potent activator of Mas-related G-protein-coupled receptors (Mrgprs), MrgprC11 and hMrgprX1, and induces scratching in mice in an Mrgpr-dependent manner. To study the sensory qualities that BAM8-22 evokes in humans, we tested the volar forearm of 15 healthy volunteers with heat-inactivated cowhage spicules previously soaked in the peptide. BAM8-22 produced itch in each subject, usually accompanied by sensations of pricking/stinging and burning. The sensations were occasionally accompanied by one or more mechanically evoked dysesthesias, namely alloknesis, hyperknesis, and/or hyperalgesia, but no wheal or neurogenic flare in the skin surrounding the application site. The inactive truncated peptide BAM8-18 produced weak or no sensations. Pretreatment of the tested skin with an antihistamine cream (doxepin) inhibited histamine-induced sensations, dysesthesias, and skin reactions but not the sensations and dysesthesias evoked by BAM8-22. We show that BAM8-22 produces itch and nociceptive sensations in humans in a histamine-independent manner. Thus, BAM8-22 may be an endogenous itch mediator that activates, in humans, MrgprX1, a novel target for potential anti-itch treatments.
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Affiliation(s)
- Parul Sikand
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut 06520, and
| | - Xinzhong Dong
- The Solomon S. Snyder Department of Neuroscience, Center for Sensory Biology, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205
| | - Robert H. LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut 06520, and
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Abstract
Prior studies have demonstrated that the prohormone, procalcitonin (ProCT), and its component calcitonin precursors (CTpr) are increased in the serum of septic patients, correlate with the severity of the illness, and persist for relatively long periods of time. Animal studies in septic hamsters have revealed that the administration of ProCT is toxic and that immunoneutralization with IgG that is reactive to this molecule significantly improves survival. A large animal model of a very rapidly lethal polymicrobial sepsis has been developed in the pig in order to measure continuous physiological and metabolic parameters and also to compare the effects in this animal of an immunoneutralization, which is performed late in the course of the disease, to an identical, but early, therapy. Based upon the physiological and metabolic parameters, the late therapy, which was initiated during the fourth hour at a time when pigs were nearly moribund, was found to be as beneficial as early therapy. In both late and early therapy, the only animals to survive at the predetermined time of euthanasia were those which had received immunoneutralization therapy.
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Affiliation(s)
- K L Becker
- George Washington University and Veterans Administration Medical Center, 50 Irving Street NW, Washington, DC 20422, USA.
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Sayyed AH, Omar D, Wright DJ. Genetics of spinosad resistance in a multi-resistant field-selected population of Plutella xylostella. Pest Manag Sci 2004; 60:827-832. [PMID: 15307676 DOI: 10.1002/ps.869] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Resistance to the bacteria-derived insecticides spinosad (Conserve), abamectin (Vertimec), Bacillus thuringiensis var kurstaki (Btk) (Dipel), B thuringiensis var aizawai (Bta) (Xentari), B thuringiensis crystal endotoxins Cry1Ac and Cry1Ca, and to the synthetic insecticide fipronil was estimated in a freshly-collected field population (CH1 strain) of Plutella xylostella (L) from the Cameron Highlands, Malaysia. Laboratory bioassays at G1 indicated significant levels of resistance to spinosad, abamectin, Cry1Ac, Btk, Cry1Ca, fipronil and Bta when compared with a laboratory insecticide-susceptible population. Logit regression analysis of F1 reciprocal crosses indicated that resistance to spinosad in the CH1 population was inherited as a co-dominant trait. At the highest dose of spinosad tested, resistance was close to completely recessive, while at the lowest dose it was incompletely dominant. A direct test of monogenic inheritance based on a back-cross of F1 progeny with CH1 suggested that resistance to spinosad was controlled by a single locus.
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Affiliation(s)
- Ali H Sayyed
- Department of Biological Sciences, Imperial College London, Silwood Park campus, Ascot, Berkshire, UK.
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Soler-Jover A, Blasi J, Gómez de Aranda I, Navarro P, Gibert M, Popoff MR, Martín-Satué M. Effect of epsilon toxin-GFP on MDCK cells and renal tubules in vivo. J Histochem Cytochem 2004; 52:931-42. [PMID: 15208360 DOI: 10.1369/jhc.4a6254.2004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Epsilon toxin (epsilon-toxin), produced by Clostridium perfringens types B and D, causes fatal enterotoxemia, also known as pulpy kidney disease, in livestock. Recombinant epsilon-toxin-green fluorescence protein (epsilon-toxin-GFP) and epsilon-prototoxin-GFP were successfully expressed in Escherichia coli. MTT assays on MDCK cells confirmed that recombinant epsilon-toxin-GFP retained the cytotoxicity of the native toxin. Direct fluorescence analysis of MDCK cells revealed a homogeneous peripheral pattern that was temperature sensitive and susceptible to detergent. epsilon-Toxin-GFP and epsilon-prototoxin-GFP bound to endothelia in various organs of injected mice, especially the brain. However, fluorescence mainly accumulated in kidneys. Mice injected with epsilon-toxin-GFP showed severe kidney alterations, including hemorrhagic medullae and selective degeneration of distal tubules. Moreover, experiments on kidney cryoslices demonstrated specific binding to distal tubule cells of a range of species. We demonstrate with new recombinant fluorescence tools that epsilon-toxin binds in vivo to endothelial cells and renal tubules, where it has a strong cytotoxic effect. Our binding experiments indicate that an epsilon-toxin receptor is expressed on renal distal tubules of mammalian species, including human.
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Affiliation(s)
- Alex Soler-Jover
- Department de Biologia Cellular i Anatomia Patològica, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain
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Kumar A, Kumar S, Sarma Dagger PVGK, Sharma Double Dagger AK. Differential conformational environment of tryptophan in epsilon native prototoxin and active toxin from Clostridium perfringens type D. J Biochem Mol Biol Biophys 2002; 6:147-50. [PMID: 12186772 DOI: 10.1080/10258140290027306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The tryptophan content of Clostridium perfringens type D epsilon protoxin and toxin was found to be one residue per molecule of protein. N-bromosuccinimide in the presence of urea cleaves the tryptophan with total loss of lethality in both toxin and prototoxin. Fluorescence spectroscopy, circular dichroism (CD) and 10% ethylene glycol solvent perturbation studies showed that the tryptophan in epsilon toxin and that in prototoxin have different conformational environments. The tryptophan is more on the surface in the prototoxin than in the toxin molecule. NBS causes total loss of lethality of the toxin with its ellipticity coming to almost zero in the near UV region of the CD.
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Affiliation(s)
- Ashok Kumar
- Division of Biochemistry, Indian Veterinary Research Institute, Izatnagar, UP India.
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11
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Meher SM, Bodhankar SL, Dhuley JN, Khodape DJ, Naik SR. Toxicity studies of microbial insecticide Bacillus thuringiensis var. kenyae in rats, rabbits, and fish. Int J Toxicol 2002; 21:99-105. [PMID: 12022636 DOI: 10.1080/10915810252866079] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Bacillus thuringiensis var. kenyae (B.t.k.) is a microbial insecticide effective against lepidopteran pest species. Acute oral toxicity in rats and acute dermal toxicity, ocular irritation, skin irritation in rabbits were studied for the wettable powder formulation of B.t.k. In addition, toxicity of the wettable powder formulation was also studied in fresh water fish (Gambussia affinis). The results of these studies indicate that this wettable powder formulation of B.t.k. is nontoxic and nonirritant to rats, rabbits, and fish.
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Affiliation(s)
- S M Meher
- Department of Pharmacology, Poona College of Pharmacy, Bharati Vidyapeeth Deemed University, Erandwane, Pune, India
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Abstract
An Australian common brown snake, Pseudonaja textilis, is known to contain highly lethal neurotoxins. Among them, a long-chain alpha-neurotoxin, pseudonajatoxin b, has been identified. In this report, while presenting evidence for the presence of at least four such long-chain alpha-neurotoxins in the venom of P. textilis, we describe the characteristics of both the mRNA and the gene responsible for the synthesis of these neurotoxins. A precursor toxin synthesized from the gene has been identified as being capable of producing the isoforms possibly by post-translational modifications at its C-terminal end. Recombinant toxins corresponding to the precursor and its product have been found to possess similar binding affinities for muscular acetylcholine receptors (IC(50)=3x10(-8) M) and a lethality, LD(50), of 0.15 microg/g in mice.
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Affiliation(s)
- N Gong
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Medical Drive, Singapore 119260
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Abstract
The activation/adaptive responses of human monocytes exposed to Bordetella pertussis parental or mutant strains were evaluated and correlated to the expression of two bacterial toxins: adenylate cyclase-hemolysin and pertussis toxin. The marked rise in intracellular cyclic adenosine monophosphate (cAMP) observed in monocytes infected by B. pertussis parental strain, inversely correlated with (1) the production of tumor necrosis factor alpha; (2) the release of superoxide anion; and (3) the expression of the 72-kDa heat shock/stress protein, Hsp70. Experiments performed with mutants deficient in adenylate cyclase-hemolysin or with purified bacterial toxins confirmed the key role of adenylate cyclase-hemolysin in the control of monocytes' response to infection by B. pertussis. This bacterial strategy primarily involves evasion from antimicrobial defenses and, eventually, the sacrifice of the host cell.
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Affiliation(s)
- E Njamkepo
- Laboratoire des Bordetella, Institut Pasteur, Paris, France
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Abstract
Epidermal growth factor (EGF) is derived from a large precursor (EGFP) of unusual structure. As EGFP remains unprocessed in certain tissues, it is of biological relevance to study its activity. Activation of the EGF receptor by EGF is involved in transformation of NIH3T3 fibroblasts. We isolated clones of NIH3T3 expressing full length, cytoplasmic region deleted or EGF-repeats deleted EGFP. All clones formed colonies in soft agarose and tumors in nude mice. Two clones expressing EGF-repeats deleted EGFP formed more and larger colonies. To conclude, EGFP is biologically active. Deletion of the 8 EGF repeats may enhance anchorage independent growth in NIH3T3.
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Affiliation(s)
- R W Kwan
- Department of Paediatrics, the University of Hong Kong, Queen Mary Hospital, Hong Kong
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15
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Abstract
We have examined the role of adenylate cyclase-hemolysin (CyaA) by constructing an in-frame deletion in the Bordetella bronchiseptica cyaA structural gene and comparing wild-type and cyaA deletion strains in natural host infection models. Both the wild-type strain RB50 and its adenylate cyclase toxin deletion (DeltacyaA) derivative efficiently establish persistent infections in rabbits, rats, and mice following low-dose inoculation. In contrast, an inoculation protocol that seeds the lower respiratory tract revealed significant differences in bacterial numbers and in polymorphonuclear neutrophil recruitment in the lungs from days 5 to 12 postinoculation. We next explored the effects of disarming specific aspects of the immune system on the relative phenotypes of wild-type and DeltacyaA bacteria. SCID, SCID-beige, or RAG-1(-/-) mice succumbed to lethal systemic infection following high- or low-dose intranasal inoculation with the wild-type strain but not the DeltacyaA mutant. Mice rendered neutropenic by treatment with cyclophosphamide or by knockout mutation in the granulocyte colony-stimulating factor locus were highly susceptible to lethal infection by either wild-type or DeltacyaA strains. These results reveal the significant role played by neutrophils early in B. bronchiseptica infection and by acquired immunity at later time points and suggest that phagocytic cells are a primary in vivo target of the Bordetella adenylate cyclase toxin.
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Affiliation(s)
- E T Harvill
- Department of Microbiology and Immunology, UCLA School of Medicine, Los Angeles, California 90095-1747, USA
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Nylen ES, Whang KT, Snider RH, Steinwald PM, White JC, Becker KL. Mortality is increased by procalcitonin and decreased by an antiserum reactive to procalcitonin in experimental sepsis. Crit Care Med 1998; 26:1001-6. [PMID: 9635646 DOI: 10.1097/00003246-199806000-00015] [Citation(s) in RCA: 238] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVES Procalcitonin (ProCT), the precursor to the calcitonin hormone, is abnormally increased in experimental and clinical systemic inflammation, including sepsis. Initially, we investigated the effects of supraphysiologic amounts of ProCT administered to animals with septic peritonitis. Subsequently, we evaluated the efficacy of prophylactic and therapeutic immune blockade of ProCT in this lethal model of sepsis. DESIGN Prospective, experimental, controlled study. SETTING Animal research laboratory approved by the American Association for the Accreditation of Laboratory Animal Care at a Veterans Affairs Medical Center. SUBJECTS Young male Golden Syrian hamsters, weighing 90 to 120 g. INTERVENTIONS In the first study, serum ProCT concentrations were measured in animals at 0, 3, 6, 12, and 24 hrs after induction of sepsis by intraperitoneal implantation of pellets containing Escherichia coli (5 x 10(8) colony-forming units/pellet). In the second study, with mortality as the end point, 30 microg/kg of isolated, purified human ProCT in 10% hamster serum (experimental) or an equal volume of 10% hamster serum (control) were administered intravenously at the time of the E. coli peritoneal implantation. In the third study, experimental animals received intraperitoneal injections of a multiregion-specific goat antiserum reactive to hamster ProCT 1 hr before and 24 hrs after E. coli implantation, while control animals received nonimmune goat serum at the same time points. In the final study, the same antiserum was administered in five divided doses during the 24 hrs after the insertion of E. coli. MEASUREMENTS AND MAIN RESULTS In the initial study, ProCT concentrations were increased shortly after induction of sepsis and peaked at 12 hrs. Administration of exogenous ProCT to septic animals significantly increased mortality compared with control animals (93% vs. 43%, p=.02). Prophylactic blockade of ProCT almost completely protected the animals from the lethal effects of sepsis: the 102-hr mortality rate in the experimental group was 6% compared with 62% in the control group (p < .003). In the therapeutic trial, the 102-hr mortality rate was 54% in experimental animals compared with 82% in control animals (p < .045). CONCLUSIONS These results demonstrate that increased ProCT exacerbates mortality in experimental sepsis, whereas neutralization of ProCT increases survival. Thus, ProCT, in addition to being an important marker of severity of systemic inflammation and mortality, is an integral part of the inflammatory process and directly affects the outcome.
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Affiliation(s)
- E S Nylen
- Department of Medicine, VA Medical Center, Washington, DC 20422, USA
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17
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Fujinaga Y, Inoue K, Watanabe S, Yokota K, Hirai Y, Nagamachi E, Oguma K. The haemagglutinin of Clostridium botulinum type C progenitor toxin plays an essential role in binding of toxin to the epithelial cells of guinea pig small intestine, leading to the efficient absorption of the toxin. Microbiology (Reading) 1997; 143 ( Pt 12):3841-3847. [PMID: 9421908 DOI: 10.1099/00221287-143-12-3841] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Binding of the purified type C 7S (neurotoxin), 12S and 16S botulinum toxins to epithelial cells of ligated small intestine or colon of the guinea pig (in vivo test) and to pre-fixed gastrointestinal tissue sections (in vitro test) was analysed. The 16S toxin bound intensely to the microvilli of epithelial cells of the small intestine in both in vivo and in vitro tests, but did not bind to cells of the stomach or colon. The neurotoxin and 12S toxin did not bind to epithelial cells of the small intestine or to cells of the stomach or colon. Absorption of the toxins was assessed by determining the toxin titre in the sera of guinea pigs 6-8 h after the intra-intestinal administration of the toxins. When the 16S toxin [1 x 10(5) minimum lethal dose (MLD)] was injected, 200-660 MLD ml-1 was detected in the sera, whereas when the 12S toxin (2 x 10(5) MLD) or 7S toxin (2 x 10(5) MLD) was injected, little toxin activity was detected in the sera. Therefore, the haemagglutinin of type C 16S toxin is apparently very important in the binding and absorption of botulinum toxin in the small intestine.
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Affiliation(s)
- Yukako Fujinaga
- Department of BacteriologyOkayama University Medical School 2-5-1 Shikata-cho, Okayama 700Japan
| | - Kaoru Inoue
- Department of BacteriologyOkayama University Medical School 2-5-1 Shikata-cho, Okayama 700Japan
| | - Sadahiro Watanabe
- Kobe City College of Nursing, 3-1 Gakuen-nishimachi, Nishi-ku, Kobe 651, Japan
| | - Kenji Yokota
- Department of BacteriologyOkayama University Medical School 2-5-1 Shikata-cho, Okayama 700Japan
| | - Yoshikazu Hirai
- Department of BacteriologyOkayama University Medical School 2-5-1 Shikata-cho, Okayama 700Japan
| | - Eiko Nagamachi
- Department of NursingSchool of Health ScienceKibi International University 8 Iga-machi, Takahashi, Okayama 716 Japan
| | - Keiji Oguma
- Department of BacteriologyOkayama University Medical School 2-5-1 Shikata-cho, Okayama 700Japan
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18
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Held HD, Raschak M, Uhlig S. Rat big endothelin-1-induced bronchoconstriction and vasoconstriction in the isolated perfused rat lung: role of endothelin converting enzyme and neutral endopeptidase 24.11. Naunyn Schmiedebergs Arch Pharmacol 1997; 355:619-24. [PMID: 9151301 DOI: 10.1007/pl00004992] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Treatment of animals with big endothelin-1 (bET) causes pulmonary hypertension and bronchoconstriction, both in vivo and in perfused lungs. The biological activity of bET requires proteolytic cleavage to ET-1 by endothelin converting enzymes (ECE) and possibly other proteases such as neutral endopeptidase 24.11 (NEP 24.11). Since the role of NEP 24.11 in the physiological activation of bET is unclear, we investigated the effects of the selective NEP 24.11 inhibitor thiorphan on bET-induced vaso- and bronchoconstriction in the isolated perfused rat lung. We also studied the effects of phosphoramidon and (S)-2-biphenyl-4-yl-1-(1H-tetraol-5-yl)-ehtylaminomethylphosphonic acid (CGS-26303), i.e. agents which block not only NEP 24.11 but also ECE. The bET-induced vasoconstriction was much less prominent than the bronchoconstriction, i.e. after exposure for 110 min vascular and airway conductance were decreased by 33% and 80% respectively. The small bET-induced vasoconstriction was attenuated to a similar degree by pretreatment with any of the three protease inhibitors. However, thiorphan up to a concentration of 10 microM had only little effect on the bET-induced bronchoconstriction, while 10 microM phosphoramidon or CGS-26303 provided half-maximal and 100 microM phosphoramidon complete protection in this model. This profile of inhibitor action suggests that in rat lung ECE is the major enzyme responsible for activation of bET.
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19
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Westrop G, Hormozi K, da Costa N, Parton R, Coote J. Structure-function studies of the adenylate cyclase toxin of Bordetella pertussis and the leukotoxin of Pasteurella haemolytica by heterologous C protein activation and construction of hybrid proteins. J Bacteriol 1997; 179:871-9. [PMID: 9006045 PMCID: PMC178772 DOI: 10.1128/jb.179.3.871-879.1997] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The adenylate cyclase toxin (CyaA) from Bordetella pertussis and the leukotoxin (LktA) from Pasteurella haemolytica are members of the RTX (stands for repeats in toxin) family of cytolytic toxins. They have pore-forming activity and share significant amino acid homology but show marked differences in biological activity. CyaA is an invasive adenylate cyclase and a weak hemolysin which is active on a wide range of mammalian cells. LktA is a cytolytic protein with a high target cell specificity and is able to lyse only leukocytes and platelets from ruminants. Each toxin is synthesized as an inactive protoxin encoded by the A gene, and the product of the accessory C gene is required for posttranslational activation. Heterologous activation of LktA by CyaC did not result in a change in its specificity for nucleated cells, although the toxin showed a greater hemolytic-to-cytotoxic ratio. LktC was unable to activate CyaA. A hybrid toxin (Hyb1), which contained the N-terminal enzymic domain and the pore-forming domain from CyaA (amino acids [aa] 1 to 687), with the remainder of the protein derived from the C-terminal end of LktA (aa 379 to 953), showed no toxic activity. Replacement of part of the LktA C-terminal domain of Hyb1 by the CyaA C-terminal domain (aa 919 to 1706) to create hybrid toxin 2 (Hyb2) partially restored toxic activity. In contrast to CyaA, Hyb2 was activated more efficiently by LktC than by CyaC, showing the importance of the region between aa 379 and 616 of LktA for activation by LktC. LktC-activated Hyb2 was more active against ruminant than murine nucleated cells, whereas CyaC-activated Hyb2 displayed a similar, but lower, activity against both cell types. These data indicate that LktC and the region with which it interacts have an influence on the target cell specificity of the mature toxin.
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Affiliation(s)
- G Westrop
- Division of Infection and Immunity, IBLS, Glasgow University, United Kingdom
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20
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Abstract
Most Bacillus thuringiensis strains producing toxins active on lepidoptera contain several plasmid-encoded delta-endotoxin genes and package related protoxins into a single inclusion. It was previously found that in B. thuringiensis subsp. aizawai HD133, which produces an inclusion comprising the CryIAb, CryIC, and CryID protoxins, there is a spontaneous loss in about 1% of the cells of a 45-mDa plasmid containing the cryIAb gene. As a result, inclusions produced by the cured strain were less readily solubilized at pH 9.2 or 9.5 and had a decreased toxicity for Plodia interpunctella, despite the presence of the CryIC protoxin, which was active when solubilized. These results suggested that protoxin composition was a factor in inclusion solubility and toxicity and that the cryIAb gene, which is also present on an unstable plasmid in several other subspecies, may have a unique role in inclusion solubility and toxicity. Introduction of a cloned copy of this gene into the plasmid-cured derivative of B. thuringiensis subsp. aizawai HD133 resulted in an increase in the solubility at pH 9.2 of all of the inclusion proteins from less than 20% to greater than 45% and a lowering of the 50% lethal concentration (LC50, in micrograms [dry weight] per square centimeter) of inclusions for Spodoptera frugiperda from 35 to 10. These values are the same as those found with inclusions from B. thuringiensis subsp. aizawai HD133, and in all cases, the LC50 of the solubilized protoxins was 10. Transformants containing related cryIA genes produced inclusions which were more than 95% solubilized at pH 9.2 but also had LC50 of 10.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Aronson
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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21
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Decoster E, Vanhaesebroeck B, Vandenabeele P, Grooten J, Fiers W. Generation and biological characterization of membrane-bound, uncleavable murine tumor necrosis factor. J Biol Chem 1995; 270:18473-8. [PMID: 7629174 DOI: 10.1074/jbc.270.31.18473] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Tumor necrosis factor (TNF) is produced as a membrane-bound, 26-kDa proform from which the mature, 17-kDa TNF subunit is released by proteolytic cleavage. In order to compare the biological activity of membrane-bound versus soluble TNF, mutational analysis of potential cleavage sites in murine TNF was carried out. The biological activity was assessed after transfection in L929 cells. Deletion of the first nine codons of the mature part of the murine TNF gene still led to the production of secretable TNF, indicating alternative cleavage sites separate from the -1/+1 junction. However, an additional deletion of 3 amino acids, generating TNF delta 1-12, resulted in a membrane-bound form of TNF. Site-directed mutagenesis revealed Lys11 as the critical residue for alternative cleavage. Mutation of this residue to Glu in a TNF delta 1-9 mutant gave rise to uncleavable, membrane-bound TNF with biological activities similar to wild-type TNF. Induction of apoptosis, proliferation, or cytokine production by triggering of either 55-kDa or 75-kDa TNF receptors in appropriate cell lines occurred efficiently both with soluble and with membrane-bound TNF. The latter was, however, less active in the cytotoxic assays on U937 cells in which the 75-kDa TNF receptor is not signaling, but contributes to maximal TNF activity by ligand passing. This indicates that membrane-bound TNF cannot be passed from the 75-kDa to the 55-kDa TNF receptor.
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Affiliation(s)
- E Decoster
- Laboratory of Molecular Biology, Gent University, Belgium
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22
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Abstract
Two different 30-nucleotide regions of the cryIAc insecticidal protoxin gene from Bacillus thuringiensis were randomly mutagenized. One region was within one of seven amphipathic helices believed to be important for the formation of ion channels. There was no loss of toxicity for three test insects by any of 27 mutants, a result similar to that obtained previously for mutations within another such helix. Only mutations within a region encoding the central helix have resulted in a substantial number of mutants with low or no toxicity. A second mutagenized region encodes amino acids which are unique to this toxin and are within one of the loops in a portion of the toxin important for specificity. Among 21 different mutations of these 10 residues, only changes of two adjacent serine residues resulted in decreased toxicity which was greater for Manduca sexta than for Heliothis virescens larvae. These mutant toxins bound poorly to the single M. sexta CryIAc vesicle-binding protein and to several of the multiple H. virescens-binding proteins. The loop containing these serines must be involved in the formation of a specific toxin recognition domain.
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Affiliation(s)
- A I Aronson
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA
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23
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Wabiko H, Yasuda E. Bacillus thuringiensis protoxin: location of toxic border and requirement of non-toxic domain for high-level in vivo production of active toxin. Microbiology (Reading) 1995; 141 ( Pt 3):629-39. [PMID: 7711901 DOI: 10.1099/13500872-141-3-629] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Insecticidal crystal proteins, or protoxins, of Bacillus thuringiensis are composed of two domains, an amino-terminal half essential for toxicity, and a carboxy-terminal half with an as yet unassigned function. To define the boundary of the two domains, sequential termination codons were introduced from the 3'-end of the DNA sequence encoding the toxic domain of the 1155-residue cry1A(b) gene product. The mutated and the intact genes were placed under the control of the Escherichia coli inducible promoter PrecA, and toxicity of the cell extracts was determined using silkworm larvae. Under non-induced conditions, in which the gene products accumulated to a limited degree, mutations encoding 606 amino acid residues or more were toxic, whereas those encoding 605 residues or less were non-toxic. Comparison of the toxicities and the levels of the toxic proteins suggested that the mutant proteins had comparable activity to that of the intact protoxin. Furthermore, the non-toxic protein seemed to be unstable in the extracts. To investigate the roles of the non-toxic domain, the mutant proteins were overproduced in both E. coli and B. thuringiensis. The intact and the mutated genes carrying natural promoters were introduced into acrystalliferous B. thuringiensis. Upon induction of PrecA in E. coli, and upon sporulation in B. thuringiensis, there was a large accumulation of gene products which formed inclusion bodies. The inclusion bodies of the intact protoxin were active, whereas those of the mutant proteins were inactive. Inclusion bodies of the intact protein could be solubilized in alkali, whereas the mutant inclusion bodies were insoluble. Since solubilization under alkaline conditions in the insect midgut is considered to be the first step of toxic action, the non-toxic domain is required to direct the synthesis of inclusion bodies as an active soluble form.
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Affiliation(s)
- H Wabiko
- Biotechnology Institute, Akita Prefectural College of Agriculture, Japan
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24
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Okumura H, Ashizawa N, Asakura R, Aotsuka T, Kobayashi F, Matsuura A. Possible involvement of different mechanisms in sudden death induced by endothelin-1 and big endothelin-1. Biol Pharm Bull 1995; 18:18-23. [PMID: 7735238 DOI: 10.1248/bpb.18.18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effects of diltiazem and phosphoramidon on sudden death induced by endothelin (ET)-1 and by big ET-1 were compared in rodents. Diltiazem (2 mg/kg, i.v.) remarkably diminished the lethal toxicity of ET-1 with a reduction in the extent of the rise in plasma immunoreactive ET-1-like activity (IR-ET-1), tissue IR-ET-1 accumulation in the heart and the rise in plasma potassium concentration. In big ET-1-induced lethality, diltiazem only slightly prolonged the latency and did not reduce the mortality. Although diltiazem moderately inhibited the rise in plasma IR-ET-1 and potassium concentration in these mice, it did not affect the accumulation of IR-ET-1 in the heart, lung or kidney. Phosphoramidon (2 mg/kg, i.v.) decreased the lethality of big ET-1 with the decrement in elevation of IR-ET-1 in the heart, lung and plasma as well as with the decrease in plasma potassium concentration, but it failed to improve any parameters in ET-1-induced lethality. In anesthetized rats, ET-1 (5 nmol/kg, i.v.) elevated ST-segment of electromyocardiograms, and diltiazem (2 mg/kg, i.v.) significantly reversed this change. Big ET-1 (25 nmol/kg, i.v.) also induced the ST-segment elevation, which was significantly inhibited by phosphoramidon but not by diltiazem. These findings suggest that accumulation of ET-1 in the heart, which may lead to lethal cardiac ischemia, is an important factor in the lethality of ET-1, while additional factors (such as hemoconcentration and bronchoconstriction) may be involved in big ET-1-induced lethality.
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Affiliation(s)
- H Okumura
- Pharmaceutical Research Laboratories, Sapporo Breweries, Ltd., Shizuoka, Japan
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25
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Szabo G, Gray MC, Hewlett EL. Adenylate cyclase toxin from Bordetella pertussis produces ion conductance across artificial lipid bilayers in a calcium- and polarity-dependent manner. J Biol Chem 1994; 269:22496-9. [PMID: 8077197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Adenylate cyclase toxin (AC toxin) from Bordetella pertussis enters target cells to produce supraphysiologic levels of cAMP and, by a cAMP-independent process, is hemolytic. In the present study, we show for the first time that this toxin also produces ion-permeable, cation-selective pores in phospholipid bilayers. The resulting membrane conductance is absolutely calcium-dependent, as are the intoxication and hemolytic activities. It is strongly affected by the polarity and magnitude of the membrane potential and enhanced by the presence of negatively charged phospholipid. AC toxins from two mutants, BPDE386 and BPD377, which are defective in toxin activity, produce little or no conductance. Finally, evaluation of the current-voltage relationships and the concentration dependence of pore formation and of hemolysis reveal a greater than 3rd power dependence, suggesting that a multimer of AC toxin, probably consisting of three or more holotoxin molecules, is involved in pore formation.
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Affiliation(s)
- G Szabo
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville 22908
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26
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Sehnke PC, Pedrosa L, Paul AL, Frankel AE, Ferl RJ. Expression of active, processed ricin in transgenic tobacco. J Biol Chem 1994; 269:22473-6. [PMID: 8077191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The cDNA encoding the plant toxin precursor preproricin was introduced into tobacco via Agrobacterium tumefaciens-mediated gene transfer. Transgenic plants were assayed for type II ribosome-inactivating protein expression and activity. Western blot analysis of soluble leaf extracts using anti-ricin a-chain (RTA) antibodies identified 34- and 32-kDa proteins, which were electrophoretically indistinguishable from castor seed RTA. Analysis with anti-ricin b-chain (RTB) antibodies identified both a 34-kDa protein major band, which co-migrated with castor seed RTB, and a 30-kDa protein minor band. Enzyme-linked immunoassay of the transgenic leaf extracts with anti-RTA and anti-RTB indicated microgram per gram production on a fresh weight basis of soluble extractable recombinant ricin. Sugar binding enzyme-linked immunoassay employing an immobilized glycoprotein, asialofetuin, and anti-RTB antibodies confirmed the characteristic type II ribosome-inactivating protein galactose binding lectin activity of the recombinant ricin. The enzymatic activity of recombinant ricin was characterized for cell-free translation inhibition, as well as for overall cytotoxicity. A 50% inhibitory dose of 3 x 10(-11) M was observed for the immunoreactive leaf extract material using a rabbit reticulocyte translation inhibition assay, while a 50% lethal dose of 1 x 10(-12) M was calculated with human T-lymphotropic virus-1 infected leukemic T-cells.
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Affiliation(s)
- P C Sehnke
- Department of Horticultural Sciences, University of Florida, Gainesville 32611
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Okumura H, Ashizawa N, Aotsuka T, Asakura R, Kobayashi F, Matsuura A. Possible mechanisms of sudden death and hemoconcentration induced by endothelin-1 and big endothelin-1 in mice. Biol Pharm Bull 1994; 17:645-50. [PMID: 7920424 DOI: 10.1248/bpb.17.645] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We investigated the profiles of sudden death and hemoconcentration induced by endothelin-1 (ET-1) and big endothelin-1 (big ET-1) in mice using various compounds as pharmacological tools. In ET-1-induced sudden death (5 nmol/kg, i.v.), pretreatment with the Ca(2+)-channel blockers, diltiazem, nifedipine or verapamil at a dose of 2 mg/kg, i.v. significantly inhibited the mortality and prolonged the latency to death. These Ca(2+)-channel blockers, however, failed to inhibit the rise in hematocrit (Ht), namely hemoconcentration, induced by ET-1 (2.5 nmol/kg). A beta-adrenoceptor agonist, isoproterenol (1 mg/kg) tended to prolong the latency, whereas, a beta-adrenoceptor blocker, propranolol (2 mg/kg), and an alpha- and beta-adrenoceptor blocker, labetalol (5 mg/kg), aggravated the sudden death. Esculetin (10 mg/kg) and fenbufen (10 mg/kg), which are enzyme inhibitors in the arachidonate cascade, prevented only the hemoconcentration. Anti-arrhythmic drugs, lidocaine (1 mg/kg) and disopyramide (20 mg/kg) did not improve any parameters. Big ET-1 also caused sudden death (20 and 25 nmol/kg, i.v.) and hemoconcentration (10 nmol/kg, i.v.). Of several proteinase inhibitors, only a metalloproteinase inhibitor, phosphoramidon (2 mg/kg i.v.), prevented the sudden death and the hemoconcentration induced by big ET-1 but not by ET-1. Ca(2+)-channel blockers exerted their protective effects only when a lower dose of big ET-1 was employed. These results indicate that the sudden death caused by both peptide is mainly due to myocardial ischemia and respiratory disorder, and that hemoconcentration caused by them is due to their vasoconstrictor action but to their effects on the vascular permeability via secondary endogenous factors.
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Affiliation(s)
- H Okumura
- Pharmaceutical Research Laboratories, Sapporo Breweries Limited, Shizuoka, Japan
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Urabe K, Aroca P, Tsukamoto K, Mascagna D, Palumbo A, Prota G, Hearing VJ. The inherent cytotoxicity of melanin precursors: a revision. Biochim Biophys Acta 1994; 1221:272-8. [PMID: 8167148 DOI: 10.1016/0167-4889(94)90250-x] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The potential cytotoxicity of the melanogenic intermediates DOPA, (L-3,4-dihydroxyphenylalanine) and DHI (5,6-dihydroxyindole) has long been recognized and exploited as a targeting concept in experimental melanoma therapy. In recent years, however, a novel branchpoint in the melanin biosynthetic pathway has been shown to divert the metabolism of DOPAchrome to a carboxylated derivative termed DHICA (DHI-2-carboxylic acid) rather than to DHI. In order to evaluate the biological implications of this regulatory control, we have reexamined the inherent cytotoxicity of DHICA versus DHI on different cell lines. We found that under the usual conditions of the biological assay, the apparent cytotoxicity of the two indoles reflect their instability in the culture medium, the less stable DHI being generally more toxic than DHICA to melanoma cells and nonmelanocytic cells. Moreover, the observed cytotoxic effects increased with the time of incubation and were markedly reduced by the addition of catalase to the medium, suggesting that they were probably due to the generation of reactive oxygen species (particularly H2O2) during the autoxidation of the melanin precursors outside the cells. To circumvent this problem, we then tested the diacetylated derivatives of DHI and DHICA (DAI and DAICA) which are sufficiently stable until taken up into the cells whereupon they may be converted by endogenous esterases back to the parent indoles. Although DAI proved to be cytotoxic for nonmelanocytic cells, it had no detectable activity on melanoma cells, whereas DAICA showed no effect on any of the cells examined. These results, when combined with other studies, point to a reconsideration of the inherent cytotoxicity of the 5,6-dihydroxyindoles, as well as DOPA, to melanin producing cells.
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Affiliation(s)
- K Urabe
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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Oppert B, Kramer KJ, Johnson DE, MacIntosh SC, McGaughey WH. Altered protoxin activation by midgut enzymes from a Bacillus thuringiensis resistant strain of Plodia interpunctella. Biochem Biophys Res Commun 1994; 198:940-7. [PMID: 8117300 DOI: 10.1006/bbrc.1994.1134] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Processing of Bacillus thuringiensis protoxins to toxins by midgut proteinases from a strain of the Indianmeal moth, Plodia interpunctella (Hubner), resistant to B. thuringiensis subspecies entomocidus (HD-198) was slower than that by midgut proteinases from the susceptible parent strain or a strain resistant to B. thuringiensis subspecies kurstaki (HD-1, Dipel). Midgut extracts from entomocidus-resistant insects exhibited five-fold lower activity toward the synthetic substrate alpha-N-benzoyl-DL-arginine rho-nitroanilide than extracts from susceptible or kurstaki-resistant insects. Midgut enzymes from susceptible or kurstaki-resistant insects converted the 133 kDa CryIA(c) protoxin to 61-63 kDa proteins, while incubations with entomocidus-resistant enzymes resulted in predominantly products of intermediate size, even with increased amounts of midgut extract. The 61-63 kDa proteins were only produced by entomocidus-resistant midgut extracts after long term incubations with the protoxin. The data suggest that altered protoxin activation by midgut proteinases is involved in some types of insect resistance to B. thuringiensis.
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Affiliation(s)
- B Oppert
- U.S. Grain Marketing Research Laboratory, ARS-USDA, Manhattan, KS 66502-2736
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Ashizawa N, Okumura H, Kobayashi F, Aotsuka T, Asakura R, Arai K, Ashikawa N, Matsuura A. Inhibitory activities of metal chelators on endothelin-converting enzyme. II. In vivo studies. Biol Pharm Bull 1994; 17:212-6. [PMID: 8205118 DOI: 10.1248/bpb.17.212] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effects of metal chelators on endothelin (ET)-converting enzyme (ECE) activity in vivo were examined. Three compounds, (2,3-dimercapto-1-propanol (DMP), toluene-3,4-dithiol (TDT) and 8-mercaptoquinoline (8-MQ)), which inhibited ECE in in vitro studies, exhibited inhibitory activity towards big ET-1-induced sudden death in mice, while EDTA did not. Similar results were obtained in big ET-1-induced hypertension. Big ET-1-induced hemoconcentration was inhibited by pretreatment with 8-MQ or EDTA but not with DMP or TDT. The elevation of immunoreactive ET-1 (IR-ET-1) in plasma after administration of big ET-1 was inhibited by pretreatment with the three compounds but not by EDTA. On the other hand, no chelator inhibited the elevation of IR-ET-1 in lung tissue after injection of big ET-1. Taking into consideration the in vitro results, more selective chelating activity of the compounds towards Zn2+ rather than Ca2+ and Mg2+ may contribute to the inhibition of big ET-1-induced responses in vivo. The ET-1 formation involved in big ET-1-induced hemoconcentration may have different physiological characteristics from that involved in big ET-1-induced sudden death or hypertension.
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Affiliation(s)
- N Ashizawa
- Pharmaceutical Research Laboratories, Sapporo Breweries Limited, Shizuoka, Japan
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Zunich KM, Lane HC, Davey RT, Falloon J, Polis M, Kovacs JA, Masur H. Phase I/II studies of the toxicity and immunogenicity of recombinant gp160 and p24 vaccines in HIV-infected individuals. AIDS Res Hum Retroviruses 1992; 8:1335. [PMID: 1466952 DOI: 10.1089/aid.1992.8.1335] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- K M Zunich
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892
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Affiliation(s)
- B S Graham
- Vaccine Clinical Trials Network, Vanderbilt University School of Medicine, Nashville, TN 37232
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Aronson AI, Han ES, McGaughey W, Johnson D. The solubility of inclusion proteins from Bacillus thuringiensis is dependent upon protoxin composition and is a factor in toxicity to insects. Appl Environ Microbiol 1991; 57:981-6. [PMID: 2059054 PMCID: PMC182833 DOI: 10.1128/aem.57.4.981-986.1991] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Bacillus thuringiensis subsp. aizawai HD133 is one of several strains particularly effective against Plodia interpunctella selected for resistance to B. thuringiensis subsp. kurstaki HD1 (Dipel). B. thuringiensis subsp. aizawai HD133 produces inclusions containing three protoxins, CryIA(b), CryIC, and CryID, and the CryIC protoxin has been shown to be active on resistant P. interpunctella as well as on Spodoptera larvae. The CryIA(b) protoxin is very similar to the major one in B. thuringiensis subsp. kurstaki HD1, and as expected, this protoxin was inactive on resistant P. interpunctella. A derivative of B. thuringiensis subsp. aizawai HD133 which had been cured of a 68-kb plasmid containing the cryIA(b) gene produced inclusions comprising only the CryIC and CryID protoxins. Surprisingly, these inclusions were much less toxic for resistant P. interpunctella and two other Lepidoptera than those produced by the parental strain, whereas the soluble protoxins from these strains were equally effective. In contrast, inclusions from the two strains were about as active as soluble protoxins for Spodoptera frugiperda larvae, so toxicity differences between inclusions may be due to the solubilizing conditions within particular larval guts. Consistent with this hypothesis, it was found that a higher pH was required to solubilize protoxins from inclusions from the plasmid-cured strain than from B. thuringiensis subsp. aizawai HD133, a difference which is probably attributable to the absence of the CryIA(b) protoxin in the former. The interactions of structurally related protoxins within an inclusion are probably important for solubility and are thus another factor in the effectiveness of B. thuringiensis isolates for particular insect larvae.
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Affiliation(s)
- A I Aronson
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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Huneidi AH, Thiemermann C, Lidbury PS, D'Orléans-Juste P, Anggård EE, Afshar F, Vane JR. Endothelin-1 and big endothelin cause subarachnoid hemorrhage in the anesthetized rabbit. J Cardiovasc Pharmacol 1991; 17 Suppl 7:S492-5. [PMID: 1725421 DOI: 10.1097/00005344-199100177-00140] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Intra-arterial injection of endothelin-1 (ET-1) (1 nmol/kg; n = 8) or human big endothelin-1 (b-ET-1; 3 nmol/kg; n = 8) into anesthetized rabbits produced a significant rise in left ventricular systolic pressure (LVSP) and caused subarachnoid hemorrhage (SAH) in 75 +/- 17% and 88 +/- 12% of the experiments, respectively. In all animals, the SAH occurred in the subarachnoid space around the distal part of the basilar artery complex. The cyclooxygenase inhibitor indomethacin (5 mg/kg i.v.) significantly potentiated the pressor effect of both peptides, and all animals pretreated with indomethacin prior to ET-1 (n = 3) or b-ET (n = 3) developed SAH. In contrast, rabbits treated with vehicle (saline; n = 7), indomethacin alone (n = 3), or the carboxy-terminal fragment of b-ET (CT 22-38; 3 nmol/kg i.a.; n = 3) developed neither a rise in LVSP nor SAH. A rise in blood pressure alone is unlikely to account for the SAH brought about by the peptides for angiotensin II (1 nmol/kg/min for 30 min; n = 7) produced a significantly greater increment in LVSP than ET-1 or b-ET, but did not cause SAH. In addition, there was no significant correlation between the rise in LVSP produced by ET-1 or b-ET and the severity of the SAH.
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Affiliation(s)
- A H Huneidi
- Department of Surgical Neurology, St. Bartholomew's Hospital Medical College, London, U.K
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Choma CT, Kaplan H. Folding and unfolding of the protoxin from Bacillus thuringiensis: evidence that the toxic moiety is present in an active conformation. Biochemistry 1990; 29:10971-7. [PMID: 2271692 DOI: 10.1021/bi00501a015] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The action of trypsin or papain on the 130-kDa crystal protein (protoxin) from Bacillus thuringiensis subsp. kurstaki HD-73 yields a 67-kDa proteinase-resistant toxic fragment (toxin) which is derived from the N-terminal half of the molecule. Sensitivity to proteolysis and fluorescence emission spectroscopy showed that the toxin unfolded to a much greater extent in 6 M guanidinium chloride (GuHCl) than in 8 M urea. Protoxin also unfolded extensively in 6 M GuHCl, whereas in 8 M urea only the C-terminal half of the molecule had unfolded extensively. Both unfolded protoxin and unfolded toxin refolded to their native and biologically active conformations. The biphasic unfolding observed for protoxin suggests that the C-terminal half of the molecule unfolded rapidly, whereas the N-terminal toxic moiety unfolded at a much slower rate, similar to that of the free 67-kDa toxin. A 67-kDa fragment, derived from the N-terminal half of the molecule, could be generated from the protoxin in the presence of either urea or GuHCl by treatment with proteinases. Compared to toxin in denaturants, this fragment was found to be more sensitive to proteolysis. However, on removal of the denaturants the fragment had the same proteinase resistance and cytolytic activity as native toxin. The increased proteinase sensitivity of the fragment generated in the presence of denaturants appears to be due to a perturbation in the conformation of the N-terminal toxic moiety. This perturbation is attributed to the unfolding of the C-terminal region of the protoxin prior to its proteolysis to yield the 67-kDa fragment.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C T Choma
- Department of Chemistry, University of Ottawa, Ontario, Canada
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Abstract
Bacillus thuringiensis subspecies kurstaki (Btk) and subspecies berliner (Btb) both produce lepidopteran-specific larvicidal protoxins with different activities against the same insect species. Toxic activity resides in the amino-terminal half of both protoxins, whereas the carboxy-terminal half of the molecules is not required for toxicity. The protoxins are 90% homologous, with a major cluster of differences in the amino-terminal half, and a 26 consecutive amino-acid insertion within the carboxy-terminal half of the Btk protoxin. Protoxin chimeras composed of the amino-terminal half of one subspecies and the carboxy-terminal half of the other were generated. Wild-type and chimeric protoxins were compared in bioassays against tobacco hornworm larvae. The amino-terminal half, the toxin itself, dictates specific larvicidal activity.
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Affiliation(s)
- K C Raymond
- Department of Molecular Biology, University of Wyoming, Laramie 82071-3944
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Hadley WM, Burchiel SW, McDowell TD, Thilsted JP, Hibbs CM, Whorton JA, Day PW, Friedman MB, Stoll RE. Five-month oral (diet) toxicity/infectivity study of Bacillus thuringiensis insecticides in sheep. Fundam Appl Toxicol 1987; 8:236-42. [PMID: 3556835 DOI: 10.1016/0272-0590(87)90122-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Bacillus thuringiensis insecticides (Bt) [Dipel (test substance D or Thuricide-HP (test substance T)] were administered in the diet for 5 months to castrated mixed rambouillet/merino sheep (24-34 kg at the beginning of the study) at a dose of 500 mg/kg/day (approximately 10(12) spores per day). No treatment-related effect was seen on weight gain or clinical chemistry parameters nor were significant gross clinical changes observed. Several blood and tissue samples taken just prior to the time the animals were killed or at necropsy were found to be positive for Bt when cultured. Detailed gross and microscopic pathologic examination of the sheep revealed several incidental lesions. However, the only lesion that may have been associated with the treatment was lymphocytic hyperplasia in Peyer's patches seen in the cecum of three sheep and it was not considered to be clinically significant.
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Cheung PY, Hammock BD. Micro-lipid-droplet encapsulation of Bacillus thuringiensis subsp. israelensis delta-endotoxin for control of mosquito larvae. Appl Environ Microbiol 1985; 50:984-8. [PMID: 3002272 PMCID: PMC291780 DOI: 10.1128/aem.50.4.984-988.1985] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The crystal delta-endotoxin of Bacillus thuringiensis subsp. israelensis is less toxic to larvae of Anopheles freeborni than to larvae of Aedes aegypti. However, when solubilized crystal was used, larvae from both species showed similar sensitivities. This effect presumably was due to the differences in feeding behavior between the two mosquito larvae when crystal preparations are used. A procedure is described whereby both crystal and solubilized B. thuringiensis subsp. israelensis toxin were emulsified with Freund incomplete adjuvant, with retention of toxicity. The use of Freund incomplete adjuvant also allowed one to assay the solubilized toxin at a low nanogram level. Furthermore, coating the toxin with lipophilic material altered the buoyancy of the toxin and reversed the sensitivities of the two mosquito larvae toward the B. thuringiensis subsp. israelensis toxin. This difference in buoyancy was determined by using an enzyme-linked immunosorbent assay that was specific for the toxic peptides. These data indicate that economically feasible buoyant formulations for the B. thuringiensis subsp. israelensis crystal can be developed.
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Worthington RW, Mülders MS, Van Rensburg JJ. Clostridium perfringens type D epsilon prototoxin. Some chemical, immunological and biological properties of a highly purified prototoxin. Onderstepoort J Vet Res 1973; 40:143-9. [PMID: 4369870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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