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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using personal computers in a grid is permitting the in silico screening of millions of molecules to seek out potential inhibitors of agents that pose bioterror threats. Current projects are targeting anthrax and smallpox, but the approach has many attractions for investigating any known protein target and its inhibition.
J Mol Graph Model 2004 Jul
PMID:Combating bioterrorism with personal computers. 1518 6

Certain pathogenic species of Bacillus and Clostridium have developed unique methods for intoxicating cells that employ the classic enzymatic "A-B" paradigm for protein toxins. The binary toxins produced by B. anthracis, B. cereus, C. botulinum, C. difficile, C. perfringens, and C. spiroforme consist of components not physically associated in solution that are linked to various diseases in humans, animals, or insects. The "B" components are synthesized as precursors that are subsequently activated by serine-type proteases on the targeted cell surface and/or in solution. Following release of a 20-kDa N-terminal peptide, the activated "B" components form homoheptameric rings that subsequently dock with an "A" component(s) on the cell surface. By following an acidified endosomal route and translocation into the cytosol, "A" molecules disable a cell (and host organism) via disruption of the actin cytoskeleton, increasing intracellular levels of cyclic AMP, or inactivation of signaling pathways linked to mitogen-activated protein kinase kinases. Recently, B. anthracis has gleaned much notoriety as a biowarfare/bioterrorism agent, and of primary interest has been the edema and lethal toxins, their role in anthrax, as well as the development of efficacious vaccines and therapeutics targeting these virulence factors and ultimately B. anthracis. This review comprehensively surveys the literature and discusses the similarities, as well as distinct differences, between each Clostridium and Bacillus binary toxin in terms of their biochemistry, biology, genetics, structure, and applications in science and medicine. The information may foster future studies that aid novel vaccine and drug development, as well as a better understanding of a conserved intoxication process utilized by various gram-positive, spore-forming bacteria.
Microbiol Mol Biol Rev 2004 Sep
PMID:Binary bacterial toxins: biochemistry, biology, and applications of common Clostridium and Bacillus proteins. 1535 62

Anthrax belongs to highly dangerous infections of man and animals. No effective treatment methods for pulmonary types of the disease have been yet developed. The existing anthrax vaccines were designed decades ago and need improvement to fit the large-scale vaccination of population. At the same time, the immunological properties of the anthrax vaccine main component, i.e. of the protective agent, have been poorly studied. We obtained, within the present case study, a panel of mouse monoclonal antibodies to the protective agent and investigated the properties of the highest-affine panel representatives. An unusual phenomenon was detected, which is related with enhancement of the anthrax toxin action on the mouse macrophage-like cell-line in presence of the 1F2 monoclonal antibody. The remaining analyzed antibodies, i.e. 6G8 and 6G7, were found to neutralize effectively the toxin action. The enhancing and neutralizing antibodies were proven to be specific to different domains of the protective antigen and to recognize epitopes in its composition. The antibody-mediated enhancement of the anthrax lethal action is a convincing argument for further development of a new-generation anthrax vaccine. Definition of the linear antigen determinants for neutralizing antibodies in the protective antigens is an important step in the development of the next-generation anthrax vaccine.
Mol Gen Mikrobiol Virusol 2004
PMID:[Monoclonal antibodies to B.anthracis protective antigen are capable to neutralize and to enhance the anthrax lethal toxin action in vitro]. 1535 37

Calcium ions regulate many cellular processes and have important structural roles in living organisms. Despite the great variety of calcium-binding proteins (CaBPs), many of them contain the same Ca(2+)-binding helix-loop-helix structure, referred to as the EF-hand. In the canonical EF-hand, the loop contains three calcium-binding aspartic acid residues, which form the DxDxDG sequence motif, and is flanked by two alpha-helices. Recently, other CaBPs containing the same motif, but lacking one or both helices, have been described. Here, structural motif searches were used to analyse the full diversity of structural context in the known set of DxDxDG-containing CaBPs, including those where the structural resemblance of a given DxDxDG motif to that of EF-hands had not been noted. The results obtained indicate that the EF-hand represents but one, among many, structural context for the DxDxDG-like Ca(2+)-binding loops. While the structural similarity of the binuclear calcium-binding sites in anthrax protective antigen and human thrombospondin suggests that they are homologous, evolutionary relationships for mononuclear sites are harder to discern. The possible scenarios for the evolution of DxDxDG motif-containing calcium-binding loops in a variety of non-homologous proteins suggested loop transplant as a mechanism perhaps responsible for much of the diversity in structural contexts of present day DxDxDG-type CaBPs. Additionally, while it can be shown that existence of a DxDxDG sequence is not enough to confer a conformation suitable for calcium binding, local convergent evolution may still have a role. The analysis presented here has consequences for the prediction of calcium binding from sequence alone.
J Mol Biol 2004 Oct 29
PMID:The DxDxDG motif for calcium binding: multiple structural contexts and implications for evolution. 1547 14

The two enzymatic components of anthrax toxin, lethal factor (LF) and edema factor (EF), are transported to the cytosol of mammalian cells by the third component, protective antigen (PA). A heptameric form of PA binds LF and/or EF and, under the acidic conditions encountered in endosomes, generates a membrane-spanning pore that is thought to serve as a passageway for these enzymes to enter the cytosol. The pore contains a 14-stranded transmembrane beta-barrel that is too narrow to accommodate a fully folded protein, necessitating that LF and EF unfold, at least partly, in order to pass. Here, we describe the pH-dependence of the unfolding of LF(N) and EF(N), the 30kDa N-terminal PA-binding domains, and minimal translocatable units, of LF and EF. Equilibrium chemical denaturation studies using fluorescence and circular dichroism spectroscopy show that each protein unfolds via a four-state mechanism: N<-->I<-->J<-->U. The acid-induced N-->I transition occurs within the pH range of the endosome (pH 5-6). The I state predominates at lower pH values, and the J and U states are populated significantly only in the presence of denaturant. The I state is compact and has characteristics of a molten globule, as shown by its retention of significant secondary structure and its ability to bind an apolar fluorophore. The N-->I transition leads to an overall 60% increase in buried surface area exposure. The J state is expanded significantly and has diminished secondary structure content. We analyze the different protonation states of LF(N) and EF(N) in terms of a linked equilibrium proton binding model and discuss the implications of our findings for the mechanism of acidic pH-induced translocation of anthrax toxin. Finally, analysis of the structure of the transmembrane beta-barrel of PA shows that it can accommodate alpha-helix, and we suggest that the steric constraints and composition of the lumen may promote alpha-helix formation.
J Mol Biol 2004 Nov 26
PMID:Acid-induced unfolding of the amino-terminal domains of the lethal and edema factors of anthrax toxin. 1553 42

Over 120 years ago, Pasteur and Greenfield developed an in vitro procedure for producing a live-attenuated Bacillus anthracis bacterial culture capable of protecting livestock from anthrax disease. Since then, anthrax has become one of the best characterized bacterial pathogens with regard to mechanism of toxicity and vaccine development. Most developments have used live-attenuated strains, bacterial supernatants or protein subunit approaches. Recently, novel plasmid DNA (pDNA) approaches to a safe and effective anthrax vaccine have been proposed. This review summarizes the history of anthrax, the need for new vaccines and recent developments in pDNA-based vaccines, leading to the initiation of a human phase I clinical trial in a significantly shorter timeframe than in traditional vaccine development.
Curr Opin Mol Ther 2004 Oct
PMID:Development of anthrax DNA vaccines. 1553 52

A DNA encoding the 27-kDa domain I of anthrax lethal factor protein (LF), was linked to the carboxyl terminus of the cholera toxin B-subunit (CTB-LF). The CTB-LF fusion gene was transferred into Solanum tuberosum cells by Agrobacterium tumefaciens-mediated in vivo transformation methods and antibiotic-resistant plants were regenerated. The CTB-LF fusion gene was detected in transformed potato leaf genomic DNA by polymerase chain reaction (PCR)-mediated DNA amplification. Immunoblot analysis with anti-CTB and anti-LF primary antibodies verified the synthesis and assembly of biologically active CTB-LF fusion protein oligomers in transformed plant tuber tissues. Furthermore, the binding of CTB-LF fusion protein pentamers to intestinal epithelial cell membrane receptors measured by GM1-ganglioside enzyme-linked immunosorbent assay (GM1-ELISA) indicated that the CTB-LF fusion protein made up approx 0.002% of the total soluble tuber protein. Synthesis of CTB-LF monomers and their assembly into biologically active CTB-LF fusion protein pentamers in potato tuber tissues demonstrates the feasibility of using edible plants for production and delivery of adjuvanted LF protein for CTB-mediated immunostimulation of mucosal immune responses against anthrax toxin.
Mol Biotechnol 2004 Nov
PMID:Synthesis and assembly of anthrax lethal factor-cholera toxin B-subunit fusion protein in transgenic potato. 1554 17

Lethal toxin (LT) is a major virulence factor secreted by anthrax bacteria. It is composed of two proteins, PA (protective antigen) and LF (lethal factor). PA transports the LF inside the cell, where LF, a zinc-dependent metalloprotease cleaves the mitogen activated protein kinase kinase (MAPKK) enzymes of the mitogen activated protein kinase (MAPK) signaling pathway, thereby impairing their function. This disruption of the MAPK pathway, which serves essential functions such as proliferation, survival and inflammation in all cell types, results in multisystem dysfunction in the host. The inactivation of the MAPK pathway in both macrophages and dendritic cells leads to inhibition of proinflammatory cytokine secretion, downregulation of costimulatory molecules such as CD80 and CD86, and ineffective T cell priming. The net result is an impaired innate and adaptive immune response. Endothelial cells of the vascular system undergo apoptosis upon LT exposure, also likely due to inactivation of the MAPK pathway. The activity of various hormone receptors such as glucocorticoids, progesterone and estrogen is also blocked, due to inhibition of p38 MAPK phosphorylation, thus affecting the body's response to stress. The present review summarizes the various disarming effects of Bacillus anthracis through the use of a single weapon, the lethal toxin.
Cell Mol Life Sci 2004 Nov
PMID:Anthrax lethal toxin: a weapon of multisystem destruction. 1555 14

The intentional use of Bacillus anthracis, the etiological agent of anthrax, as a bioterrorist weapon in late 2001 made our society acutely aware of the importance of developing, testing, and stockpiling adequate countermeasures against biological attacks. Biodefense vaccines are an important component of our arsenal to be used during a biological attack. However, most of the agents considered significant threats either have been eradicated or rarely infect humans alive today. As such, vaccine efficacy cannot be determined in human clinical trials but must be extrapolated from experimental animal models. This article reviews the efficacy and immunogenicity of human anthrax vaccines in well-defined animal models and the progress toward developing a rugged immunologic correlate of protection. The ongoing evaluation of human anthrax vaccines will be dependent on animal efficacy data in the absence of human efficacy data for licensure by the U.S. Food and Drug Administration.
Microbiol Mol Biol Rev 2004 Dec
PMID:Rabbit and nonhuman primate models of toxin-targeting human anthrax vaccines. 1559 Jul 76

Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for studying bimolecular interactions at the atomic scale. Our NMR laboratory is involved in the identification of small molecules, or ligands, that bind to target protein receptors such as tetanus neurotoxin (TeNT) and botulinum neurotoxin, anthrax proteins, and HLA-DR10 receptors on non-Hodgkin lymphoma cancer cells. Once low-affinity binders are identified, they can be linked together to produce multidentate synthetic high-affinity ligands (SHALs) that have very high specificity for their target protein receptors. An important nanotechnology application for SHALs is their use in the development of robust chemical sensors or biochips for the detection of pathogen proteins in environmental samples or body fluids. Here we describe a recently developed NMR competition assay based on transferred nuclear Overhauser effect spectroscopy that enables the identification of sets of ligands that bind to the same site, or a different site, on the surface of TeNT fragment C (TetC) than a known "marker" ligand, doxorubicin. Using this assay, one can identify the optimal pairs of ligands to be linked together for creating detection reagents, as well as estimate the relative binding constants for ligands competing for the same site.
Methods Mol Biol 2005
PMID:Application of NMR methods to identify detection reagents for use in development of robust nanosensors. 1565 83


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