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The paper contains a survey of published data about the use of DNA-diagnostics in indicating and identifying the causative agents of highly dangerous infections like plague, cholera and anthrax. A discussion of data about the genetic relationship between strains of the mentioned causative agents isolated from different sources by using the molecular-typing methods as well as about the evolution ties between strains of different origins is in the focus of attention. Results of comparative studies of nucleotide sequences of genomes or of individual genomes in different Yersinia pestis, Vibrio cholerae and Bacillus anthracis strains, which are indicative of the evolution of their pathogenicity, are also under discussion.
Mol Gen Mikrobiol Virusol 2003
PMID:[Genodiagnosis and molecular typing of the pathogens for plague, cholera, and anthrax]. 1265 42

Certain mutations within the protective antigen (PA) moiety of anthrax toxin endow the protein with a dominant-negative (DN) phenotype, converting it into a potent antitoxin. Proteolytically activated PA oligomerizes to form ring-shaped heptameric complexes that insert into the membrane of an acidic intracellular compartment and promote translocation of bound edema factor and/or lethal factor to the cytosol. DN forms of PA co-oligomerize with the wild-type protein and block the translocation process. We prepared and characterized 4 DN forms: a single, a double, a triple, and a quadruple mutant. The mutants were made by site-directed mutation of the cloned form of PA in Escherichia coli and tested by various assays conducted on CHO cells or in solution. All 4 mutant PAs were competent for heptamerization and ligand binding but were defective in the pH-dependent functions: pore formation, ability to convert to the SDS-resistant heptamer, and ability to translocate bound ligand. The single mutant (F427K) showed less attenuation than the others in the pH-dependent functions and lower DN activity in a CHO cell assay. The quadruple (K397D + D425K + F427A + 2beta2-2beta3) deletion showed the most potent DN activity at low concentrations but also gave indications of low stability in a urea-mediated unfolding assay. The double mutant (K397D + D425K) and the triple (K397D + D425K + F427A) showed strong DN activity and slight reduction in stability relative to the wild-type protein. The properties of the double and the triple mutants make these forms worthy of testing in vivo as a new type of antitoxic agent for treatment of anthrax.
Mol Med
PMID:Characterization of dominant-negative forms of anthrax protective antigen. 1276 39

The members of Bacillus species are Gram-positive, ubiquitous spore-forming bacilli. Several genomic sequences have been made available during recent years, including Bacillus subtilis, a model organism among this genus, Bacillus anthracis, and their analyses provided a wealth of information about spore-forming bacteria. Some members of this species can cause serious diseases in livestock and humans. An important pathogen in this group of organisms is B. anthracis, which is the causative agent of anthrax. A summary of the B. subtilis genome information, based on the publicly released sequence, that allowed for the identification and characterization of new and novel proteins of this organism as well as similar proteins from other members of Bacillus species is provided. The primary goal for this work is to present a review of the genome sequence-identified genes that encode proteins involved in the sporulation, germination, and outgrowth processes. These three processes are essential for spore development and later its transformation into a vegetative cell. Additionally, for a few selected examples of the protein products of the identified genes, the application of bioinformatics and modeling tools is illustrated in order to determine their likely structure and function. Two three-dimensional models of the structures of such proteins, PrfA endonuclease and phosphatase PhoE, are presented together with the structure-based functional conclusions. The review of such studies provides an example of how the genomic sequence can be utilized in order to elucidate the structure and function of proteins, in particular proteins of the Bacillus species. Because only a limited number of proteins of Bacillus species organisms are involved in the synthesis and degradation of spores and have been characterized to date, this genome-based analysis may provide new insights into the developmental processes of bacterial organism.
Crit Rev Biochem Mol Biol 2003
PMID:Bacillus species proteins involved in spore formation and degradation: from identification in the genome, to sequence analysis, and determination of function and structure. 1287 Jul 14

Gene transfer to salivary glands by retrograde perfusion of the salivary duct has been shown to result in production of the encoded protein. We sought to determine if this technique would be useful for genetic immunization. In studies that compare delivery of DNA to either the salivary gland (SG) or muscle (im), mean plasma IgG and IgA titers obtained following SG delivery were 46- and 86-fold greater, respectively, than those following im delivery. We also tested the hypothesis that SG vaccination could generate mucosal responses in sites proximal and distal to DNA administration. SG-treated animals produced specific antibodies within saliva, vaginal fluid, and lung washes as well as demonstrating robust specific responses in Peyer's patches. In a test of functional immunity, animals vaccinated with DNA by SG retrograde perfusion were significantly more resistant to the effects of lethal anthrax challenge than im DNA-vaccinated animals. These data suggest that SG genetic immunization may offer advantages over conventional routes of vaccination.
Mol Ther 2003 Sep
PMID:Systemic and mucosal antibody responses following retroductal gene transfer to the salivary gland. 1294 12

Recent events have created an urgent need for new therapeutic strategies to treat anthrax. We have applied a mixture-based peptide library approach to rapidly determine the optimal peptide substrate for the anthrax lethal factor (LF), a metalloproteinase with an important role in the pathogenesis of the disease. Using this approach we have identified peptide analogs that inhibit the enzyme in vitro and that protect cultured macrophages from LF-mediated cytolysis. The crystal structures of LF bound to an optimized peptide substrate and to peptide-based inhibitors provide a rationale for the observed selectivity and may be exploited in the design of future generations of LF inhibitors.
Nat Struct Mol Biol 2004 Jan
PMID:The structural basis for substrate and inhibitor selectivity of the anthrax lethal factor. 1471 24

The virulent spore-forming bacterium Bacillus anthracis secretes anthrax toxin composed of protective antigen (PA), lethal factor (LF) and edema factor (EF). LF is a Zn-dependent metalloprotease that inactivates key signaling molecules, such as mitogen-activated protein kinase kinases (MAPKK), to ultimately cause cell death. We report here the identification of small molecule (nonpeptidic) inhibitors of LF. Using a two-stage screening assay, we determined the LF inhibitory properties of 19 compounds. Here, we describe six inhibitors on the basis of a pharmacophoric relationship determined using X-ray crystallographic data, molecular docking studies and three-dimensional (3D) database mining from the US National Cancer Institute (NCI) chemical repository. Three of these compounds have K(i) values in the 0.5-5 microM range and show competitive inhibition. These molecular scaffolds may be used to develop therapeutically viable inhibitors of LF.
Nat Struct Mol Biol 2004 Jan
PMID:Identification of small molecule inhibitors of anthrax lethal factor. 1471 25

Systemic anthrax infections can be characterized as proceeding in stages, beginning with an early intracellular establishment stage within phagocytes that is followed by extracelluar stages involving massive bacteraemia, sepsis and death. Because most bacteria require iron, and the host limits iron availability through homeostatic mechanisms, we hypothesized that B. anthracis requires a high-affinity mechanism of iron acquisition during its growth stages. Two putative types of siderophore synthesis operons, named Bacillus anthracis catechol, bac (anthrabactin), and anthrax siderophore biosynthesis, asb (anthrachelin), were identified. Directed gene deletions in both anthrabactin and anthrachelin pathways were generated in a B. anthracis (Sterne) 34F2 background resulting in mutations in asbA and bacCEBF. A decrease in siderophore production was observed during iron-depleted growth in both the DeltaasbA and DeltabacCEBF strains, but only the DeltaasbA strain was attenuated for growth under these conditions. In addition, the DeltaasbA strain was severely attenuated both for growth in macrophages (MPhi) and for virulence in mice. In contrast, the DeltabacCEBF strain did not differ phenotypically from the parental strain. These findings support a requirement for anthrachelin but not anthrabactin in iron assimilation during the intracellular stage of anthrax.
Mol Microbiol 2004 Jan
PMID:Bacillus anthracis requires siderophore biosynthesis for growth in macrophages and mouse virulence. 1475 82

The review describes the history of creation and development of the microchip technology and its role in the human genome project in Russia. The emphasis is placed on the three-dimensional gel-based microchips developed at the Center of Biological Microchips headed by A.D. Mirzabekov since 1988. The gel-based chips of the last generation, IMAGE chips (Immobilized Micro Array of Gel Elements), have a number of advantages over the previous versions. The microchips are manufactured by photo-initiated copolymerization of gel components and immobilized molecules (DNA, proteins, and ligands). This ensures an even distribution of the immobilized probe throughout the microchip gel element with a high yield (about 50% for oligonucleotides). The use of methacrylamide as a main component of the polymerization mixture resulted in a substantial increase of gel porosity without affecting its mechanical strength and stability, which allowed one to work with the DNA fragments of up to 500 nt in length, as well as with rather large protein molecules. At present, the gel-based microchips are widely applied to address different problems. The generic microchips containing a complete set of possible hexanucleotides are used to reveal the DNA motifs binding with different proteins and to study the DNA-protein interactions. The oligonucleotide microchips are a cheap and reliable tool of diagnostics designed for mass application. Biochips have been developed for identification of the tuberculosis pathogen and its antibiotic-resistant forms; for diagnostics of orthopoxviruses, including the smallpox virus; for diagnostics of the anthrax pathogen; and for identification of chromosomal rearrangements in leukemia patients. The protein microchips can be adapted for further use in proteomics. Bacterial and yeast cells were also immobilized in the gel, maintaining their viability, which open a wide potential for creation biosensors on the basis of microchips.
Mol Biol (Mosk)
PMID:[Microchips based on three dimensional gel cells: history and perspective]. 1504 31

The stoichiometry of a protein complex can be calculated from an accurate measurement of the complex's molecular weight. Multiangle laser light scattering in combination with size-exclusion chromatography and interferometric refractometry provides a powerful means for determining the molecular weights of proteins and protein complexes. In contrast to conventional size-exclusion chromatography and analytical centrifugation, measurements do not rely on the use of molecular weight standards and are not affected by the shape of the proteins. The technique is based on the direct relationship between the amount of light scattered by a protein in solution and the product of its concentration and molecular weight. A typical experimental configuration includes a size-exclusion column to fractionate the sample, a light-scattering detector to measure scattered light, and an interferometric refractometer to measure protein concentration. The determination of the molecular weight of an anthrax toxin complex will be examined to illustrate how multiangle laser light scattering can be used to determine the stoichiometry of protein complexes.
Methods Mol Biol 2004
PMID:Using light scattering to determine the stoichiometry of protein complexes. 1506 52

We describe the synthesis of an inhibitor that interferes with critical protein-protein interactions occurring during the assembly of anthrax toxin. Using a phage display selection strategy, we isolated a peptide directed against the cell binding moiety of the toxin that was able to interfere with binding of the enzymatic moieties. Because the cell binding moiety of the toxin is a heptamer, the peptide can potentially bind up to seven equivalent sites. We synthesized a polyvalent molecule displaying multiple copies of this peptide and showed that it is a much more potent inhibitor than the free peptide. Because little structural knowledge of the interacting proteins was required to synthesize this inhibitor, we believe that this approach may prove useful in the design of inhibitors of protein-protein interactions in other systems.
Methods Mol Biol 2004
PMID:Use of phage display and polyvalency to design inhibitors of protein-protein interactions. 1506 61


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