Anthrax toxin edema factor: a bacterial adenylate cyclase that increases cyclic AMP concentrations of eukaryotic cells.
01 May 1982-Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences)-Vol. 79, Iss: 10, pp 3162-3166
TL;DR: It is shown here that EF is an adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1] produced by Bacillus anthracis in an inactive form and nearly equals that of the most active known cyclase.
Abstract: Anthrax toxin is composed of three proteins: protective antigen (PA), lethal factor (LF), and edema factor (EF). These proteins individually cause no known physiological effects in animals but in pairs produce two toxic actions. Injection of PA with LF causes death of rats in 60 min, whereas PA with EF causes edema in the skin of rabbits and guinea pigs. The mechanisms of action of these proteins have not been determined. It is shown here that EF is an adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] produced by Bacillus anthracis in an inactive form. Activation occurs upon contact with a heat-stable eukaryotic cell material. The specific activity of the resulting adenylate cyclase nearly equals that of the most active known cyclase. In Chinese hamster ovary cells exposed to PA and EF, cAMP concentrations increase without a lag to values about 200-fold above normal, remain high in the continued presence of toxin, and decrease rapidly after its removal. The increase in cAMP is completely blocked by excess LF. It is suggested that PA interacts with cells to form a receptor system by which EF and perhaps LF gain access to the cytoplasm.
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TL;DR: It is shown that LF is a protease that cleaves the amino terminus of mitogen-activated protein kinase kinases 1 and 2 and that this cleavage inactivates MAPKK1 and inhibits the MAPK signal transduction pathway.
Abstract: Anthrax lethal toxin, produced by the bacterium Bacillus anthracis, is the major cause of death in animals infected with anthrax. One component of this toxin, lethal factor (LF), is suspected to be a metalloprotease, but no physiological substrates have been identified. Here it is shown that LF is a protease that cleaves the amino terminus of mitogen-activated protein kinase kinases 1 and 2 (MAPKK1 and MAPKK2) and that this cleavage inactivates MAPKK1 and inhibits the MAPK signal transduction pathway. The identification of a cleavage site for LF may facilitate the development of LF inhibitors.
1,006Â citations
TL;DR: The cloning of the human PA receptor is described using a genetic complementation approach and a soluble version of this domain can protect cells from the action of the toxin.
Abstract: The tripartite toxin secreted by Bacillus anthracis, the causative agent of anthrax, helps the bacterium evade the immune system and can kill the host during a systemic infection. Two components of the toxin enzymatically modify substrates within the cytosol of mammalian cells: oedema factor (OF) is an adenylate cyclase that impairs host defences through a variety of mechanisms including inhibiting phagocytosis; lethal factor (LF) is a zinc-dependent protease that cleaves mitogen-activated protein kinase kinase and causes lysis of macrophages. Protective antigen (PA), the third component, binds to a cellular receptor and mediates delivery of the enzymatic components to the cytosol. Here we describe the cloning of the human PA receptor using a genetic complementation approach. The receptor, termed ATR (anthrax toxin receptor), is a type I membrane protein with an extracellular von Willebrand factor A domain that binds directly to PA. In addition, a soluble version of this domain can protect cells from the action of the toxin.
884Â citations
TL;DR: The recent elucidation of the three-dimensional structure of the heat-labile enterotoxin has provided an opportunity to examine and compare the correlations between structure and function of the two toxins, which may improve understanding of the disease process itself and illuminate the role of the toxin in studies of signal transduction and G-protein function.
863Â citations
TL;DR: Advances in understanding the entry process include insights into how PA recognizes its two known receptors and its ligands, LF and EF; how the PA:receptor interaction influences the pH-dependence of pore formation; and how the pore functions in promoting translocation of LF andEF across the endosomal membrane.
Abstract: Anthrax toxin consists of three nontoxic proteins that self-assemble at the surface of receptor-bearing mammalian cells or in solution, yielding a series of toxic complexes. Two of the proteins, called Lethal Factor (LF) and Edema Factor (EF), are enzymes that act on cytosolic substrates. The third, termed Protective Antigen (PA), is a multifunctional protein that binds to receptors, orchestrates the assembly and internalization of the complexes, and delivers them to the endosome. There, the PA moiety forms a pore in the endosomal membrane and promotes translocation of LF and EF to the cytosol. Recent advances in understanding the entry process include insights into how PA recognizes its two known receptors and its ligands, LF and EF; how the PA:receptor interaction influences the pH-dependence of pore formation; and how the pore functions in promoting translocation of LF and EF across the endosomal membrane.
584Â citations
TL;DR: It is suggested that anthrax lethal toxin requires passage through an acidic endocytic vesicle in order to exert its toxic effect within the cytosol.
540Â citations
References
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Journal Article•
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
289,852Â citations
Journal Article•
532Â citations
TL;DR: The data suggest that cyclic AMP may be an important factor in the determination of morphology of normal fibroblasts and this function may be lost or altered during transformation.
Abstract: Sarcoma cells growing in tissue culture have morphological and growth characteristics different than normal fibroblasts. Several of the morphological characteristics of normal fibroblasts are regained when the cells are incubated with dibutyryl-cyclic AMP or butyryl-cyclic AMP (0.1-1 mM), or cyclic AMP (3 mM) plus theophylline (1 mM), but not with ATP, ADP, AMP, adenine, or adenosine (1-7 mM). The cell bodies become elongated; distinct narrow processes are formed. With prolonged incubation, the cells show less tendency to pile up or become polygonal. Further, L-929 and Rous sarcomatransformed hamster cells orient in parallel arrays characteristic of contact inhibition. The cells retain their altered morphology as long as the butyryl-cyclic AMP is present, but revert after its removal. Experiments with cycloheximide, puromycin, and actinomycin D indicate that protein Synthesis, but not RNA synthesis, is required for the response. Microtubular proteins may be involved. No response is observed with normal fibroblasts or with various epithelial cells. The data suggest that cyclic AMP may be an important factor in the determination of morphology of normal fibroblasts and this function may be lost or altered during transformation.
403Â citations
TL;DR: An attempt is made to evaluate the mechanism of action of NAD Glycohydrolase and ADP-Ribosyltransferase on GTP-Binding Protein and GTPase Activity in response to the presence of Gangliosides and Their Oligosaccharides in Choleragen.
Abstract: PERSPECTIVES AND SUMMARY S82 ROLE OF GANGLIOSIDE GMI AS THE CELL SURFACE RECEPTOR FOR CHOLERAGEN ......... ...... . . . ....... . ......... ...... .... 583 Interaction of Gangliosides and Their Oligosaccharides with Choleragen and Its Subunits 584 Activation of Adenylate Cyclase by Choleragen in Intact Cells 585 Activation of Adenylate Cyclase by Choleragen in Cell-Free Systems . 587 REQUIREMENTS FOR DEMONSTRATION OF ADENYLATE CYCLASE ACTIVATION BY CHOLERAGEN IN CELL-FREE SySTEMS ....... . .. 588 NAD !i88 GTP 588 Calcium-Dependent Regulatory Protein 589 ROLE OF NAD AS SUBSTRATE IN REACTIONS CATALYZED BY CHOLERAGEN 589 Mechanism of Action of NAD-Dependent Pseudomonas EXotoxin A and Diphtheria Toxin .... . . . ....... ..... ......... 590 NAD Glycohydrolase and ADP-Ribosyltransferase Activities oj Choleragen 591 Effects ofCholeragen on GTP-Binding Protein and GTPase Activity 592 SIMILARITIES BETWEEN CHOLERAGEN AND ESCHERICHIA COLI HEAT-LABILE ENTEROTOXIN 593 AN ADP-RIBOSYLTRANSFERASE FROM TURKEY ERYTHROCYTES WITH CHOLERAGEN-LIKE ACTIVITy .... . . . . . . . . . . . 595
365Â citations
TL;DR: A Permeability Factor (Toxin) found in Cholera Stools and Culture Filtrates and its Neutralization by Convalescent CholERA Sera is found to be neutralized by convalescent cholera patients.
Abstract: A Permeability Factor (Toxin) Found in Cholera Stools and Culture Filtrates and its Neutralization by Convalescent Cholera Sera
266Â citations