A5103266647- Bacillus and Francisella bacterial research
- Bacterial Genetics and Biotechnology
- Bacteriophages and microbial interactions
- Clostridium difficile and Clostridium perfringens research
- Yersinia bacterium, plague, ectoparasites research
- Viral gastroenteritis research and epidemiology
- Toxin Mechanisms and Immunotoxins
- Microbial Inactivation Methods
- Microscopic Colitis
- Vibrio bacteria research studies
- Antibiotic Resistance in Bacteria
- Escherichia coli research studies
- Bacterial biofilms and quorum sensing
- Probiotics and Fermented Foods
- Salmonella and Campylobacter epidemiology
- Antimicrobial Resistance in Staphylococcus
- Microbial Natural Products and Biosynthesis
- Insect and Pesticide Research
- Helicobacter pylori-related gastroenterology studies
- Transgenic Plants and Applications
- Gut microbiota and health
- Genetically Modified Organisms Research
- Zoonotic diseases and public health
- Biochemical and Structural Characterization
- Porphyrin Metabolism and Disorders
University of Michigan
2012-2022
Michigan United
2010-2017
Tauri Group (United States)
2016
Bipar
2009-2015
Center for Biologics Evaluation and Research
2015
John F. Kennedy Medical Center
2012
Max Planck Institute for Infection Biology
2010
University of Minnesota
2007
Duke University Hospital
1997-1999
Duke Medical Center
1997-1999
We have recently described a genetic system, termed in vivo expression technology (IVET), that uses an animal as selective medium to identify genes pathogenic bacteria specifically express when infecting host tissues. Here, the potential utility of IVET approach has been expanded with development transcriptional-fusion vector, pIVET8, which antibiotics resistance basis for selection pIVET8 contains promoterless chloramphenicol acetyltransferase (cat) and lacZY genes. A pool Salmonella...
In vivo e xpression t echnology (IVET) has been used to identify >100 Salmonella typhimurium genes that are specifically expressed during infection of BALB/c mice and/or murine cultured macrophages. Induction these is shown be required for survival in the animal under conditions IVET selection. One class i nduced ( ivi ) genes, iviVI-A and iviVI-B , constitute an operon resides a region genome with low G+C content presumably acquired by horizontal transfer. These encode predicted proteins...
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, the host limits iron availability through homeostatic mechanisms, we hypothesized B. anthracis requires a high-affinity mechanism of acquisition during its growth stages. Two putative types siderophore synthesis operons,...
This study describes early intracellular events occurring during the establishment phase of Bacillus anthracis infections. Anthrax infections are initiated by dormant endospores gaining access to mammalian host and becoming engulfed regional macrophages (Mφ). During systemic anthrax, late stage include vegetative growth in blood very high titres synthesis anthrax exotoxin complex, which causes disease symptoms death. Experiments focus on first few hours B. infectious cycle, from endospore...
The endospores of Bacillus anthracis are the infectious particles anthrax. Spores dormant bacterial morphotypes able to withstand harsh environments for decades, which contributes their ability be formulated and dispersed as a biological weapon. We monitored gene expression in B. during growth sporulation using full genome DNA microarrays matched results against comprehensive analysis mature anthrax spore proteome. A large portion (approximately 36%) is regulated phase-dependent manner, this...
The edema factor (EF) and lethal (LF) components of anthrax toxin require protective antigen (PA) for binding entry into mammalian cells. After internalization by receptor-mediated endocytosis, PA facilitates the translocation EF LF across membrane an acidic intracellular compartment. To characterize process, we generated chimeric proteins composed recognition domain (LFN; residues 1-255) fused to either amino-terminus or carboxy-terminus catalytic chain diphtheria (DTA). purified fusion...
A complete copy of the gene (cpe) encoding Clostridium perfringens enterotoxin (CPE), an important virulence factor involved in C. food poisoning and other gastrointestinal illnesses, has been cloned, sequenced, expressed Escherichia coli. The cpe was shown to encode a 319-amino-acid polypeptide with deduced molecular weight 35,317. There no consensus sequence for typical signal peptide present 5' region cpe. Cell lysates from recombinant cpe-positive E. coli were by quantitative immunoblot...
ABSTRACT Specific combinations of amino acids or purine ribonucleosides and are required for efficient germination endospores Bacillus anthracis ΔSterne, a plasmidless strain, at ligand concentrations in the low-micromolar range. The acid l -alanine was only independent germinant B. then >10 mM. Inosine both play major roles as cogerminants with several other acting (His, Pro, Trp, Tyr combining Ala, Cys, His, Met, Phe, Ser, Tyr, Val inosine). An ortholog to subtilis tricistronic receptor...
The asbABCDEF gene cluster from Bacillus anthracis is responsible for biosynthesis of petrobactin, a catecholate siderophore that functions in both iron acquisition and virulence murine model anthrax. We initiated studies to determine the biosynthetic details petrobactin assembly based on mutational analysis asb operon, identification accumulated intermediates, addition exogenous siderophores mutant strains. As starting point, in-frame deletions each genes locus (asbABCDEF) were constructed....
Siderophores are high-affinity iron chelators produced by microorganisms and frequently contribute to the virulence of human pathogens. Targeted inhibition biosynthesis siderophores staphyloferrin B Staphylococcus aureus petrobactin Bacillus anthracis hold considerable potential as a single or combined treatment for methicillin-resistant S. (MRSA) anthrax infection, respectively. The biosynthetic pathways both involve nonribosomal peptide synthetase independent siderophore (NIS) synthetase,...
Clostridium difficile (C. difficile) is an anaerobic gram-positive pathogen that the leading cause of nosocomial bacterial infection globally. C. (CDI) typically occurs after ingestion infectious spores by a patient has been treated with broad-spectrum antibiotics. While CDI toxin-mediated disease, transmission and pathogenesis are dependent on ability to produce viable spores. These must become metabolically active (germinate) in order disease. spore germination when encounter bile salts...
ABSTRACT Salmonella typhimurium in vivo-induced ( ivi ) genes were grouped by their coordinate behavior response to a wide variety of environmental and genetic signals, including pH, Mg 2+ , Fe PhoPQ. All the seven fusions that are induced both low pH (e.g., iviVI-A activated PhoPQ regulatory system. Iron-responsive include those under iron limitation entF as well one excess but only absence PhoP pdu ). Intracellular expression studies showed each pH- -responsive is upon entry into growth...
Bacillus anthracis begins its infectious cycle as a metabolically dormant cell type, the endospore. Upon entry into host, endospores rapidly differentiate vegetative bacilli through process of germination, thus initiating anthrax. Elucidation signals that trigger germination and receptors recognize them is critical to understanding pathogenesis B. anthracis. Individual mutants deficient in each seven putative germinant receptor-encoding loci were constructed via temperature-dependent,...
In this study a short sequence encoding the receptor-binding activity of much larger 35-kDa enterotoxin elaborated by Clostridium perfringens was localized recombinant DNA techniques. Defined fragments corresponding to portions gene were cloned into an Escherichia coli expression vector system, and these lysates analyzed for their ability compete binding with native C. (CPE). The lysate containing CPE290-319 (CPE encompassing residues 290-319) shown 125I-CPE specific sites on rabbit...
The life cycle of Bacillus anthracis includes both vegetative and endospore morphologies which alternate based on nutrient availability, there is considerable evidence indicating that the ability this organism to cause anthrax depends its progress through in a regulated manner. Here we report use custom B. GeneChip defining gene expression patterns occur throughout entire vitro. Nearly 5,000 genes were expressed five distinct waves transcription as bacteria progressed from germination...
Bacillus anthracis produces two catecholate siderophores, petrobactin and bacillibactin, under iron-limited conditions. Here, we investigate how variable iron oxygen concentrations influence the biosynthetic output of both siderophores in B. anthracis. In addition, describe differential levels transcription select genes within siderophore operons that are responsible for synthesis during growth conditions.Accumulation bacillibactin Sterne (34F(2)) a mutant lacking major superoxide dismutase...
Clostridium perfringens type A enterotoxin (CPE) is a membrane-active cytotoxin. There are number of recognized early steps in CPE cytotoxicity including binding to protein receptor, insertion into membranes, and CPE-mediated induction changes membrane permeability for small molecules such as ions amino acids. Further support the existence these further characterization events presented this report. We now report that action largely independent extracellular divalent cations. It also shown...
The interaction between Bacillus anthracis and the mammalian phagocyte is one of central stages in progression inhalational anthrax, it commonly believed that host cell plays a key role facilitating germination dissemination inhaled B. spores. Given this, detailed definition survival strategies used by within critical for our understanding anthrax. In this study, we report first genome-wide analysis gene expression during infection phagocytes. We developed technique specific isolation...
Recently, iron acquisition and, more specifically, enzymes involved in siderophore biosynthesis have become attractive targets for discovery of new antibiotics. Accordingly, targeted inhibition the petrobactin, a virulence-associated encoded by asb locus Bacillus anthracis, may hold promise as potential therapy against anthrax. This study describes biochemical characterization AsbC, first reported 3,4-dihydroxybenzoic acid-AMP ligase, and key component DHB-spermidine (DHB-SP), isolable...