8 results on '"Anderson, Erica C."'
Search Results
2. The germination-specific lytic enzymes SleB, CwlJ1, and CwlJ2 each contribute to Bacillus anthracis spore germination and virulence
- Author
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Giebel, Jonathan D., Carr, Katherine A., Anderson, Erica C., and Hanna, Philip C.
- Subjects
Bacillus anthracis -- Genetic aspects ,Bacillus anthracis -- Physiological aspects ,Spores (Bacteria) -- Research ,Virulence (Microbiology) -- Research ,Biological sciences - Abstract
The bacterial spore cortex is critical for spore stability and dormancy and must be hydrolyzed by germination-specific lytic enzymes (GSLEs), which allows complete germination and vegetative cell outgrowth. We created in-frame deletions of three genes that encode GSLEs that have been shown to be active in Bacillus anthracis germination: sleB, cwlJ1, and cwlJ2. Phenotypic analysis of individual null mutations showed that the removal of any one of these genes was not sufficient to disrupt spore germination in nutrient-rich media. This finding indicates that these genes have partially redundant functions. Double and triple deletions of these genes resulted in more significant defects. Although a small subset of [DELTA]sleB [DELTA]cwlJ1 spores germinate with wild-type kinetics, for the overall population there is a 3-order-of-magnitude decrease in the colony-forming efficiency compared with wild-type spores. [DELTA]sleB [DELTA]cwlJ1 [DELTA]cwlJ2 spores are unable to complete germination in nutrient-rich conditions in vitro. Both [DELTA]sleB [DELTA]cwlJ1 and [DELTA]sleB [DELTA]cwlJ1 [DELTA]cwlJ2 spores are significantly attenuated, but are not completely devoid of virulence, in a mouse model of inhalation anthrax. Although unable to germinate in standard nutrient-rich media, spores lacking SleB, CwlJ1, and CwlJ2 are able to germinate in whole blood and serum in vitro, which may explain the persistent low levels of virulence observed in mouse infections. This work contributes to our understanding of GSLE activation and function during germination. This information may result in identification of useful therapeutic targets for the disease anthrax, as well as provide insights into ways to induce the breakdown of the protective cortex layer, facilitating easier decontamination of resistant spores.
- Published
- 2009
3. Transcriptional profiling of the Bacillus anthracis life cycle in vitro and an implied model for regulation of spore formation
- Author
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Bergman, Nicholas H., Anderson, Erica C., Swenson, Ellen E., Niemeyer, Matthew M., Miyoshi, Amy D., and Hanna, Philip C.
- Subjects
Bacillus anthracis -- Environmental aspects ,Bacillus anthracis -- Genetic aspects ,Animal life cycles -- Analysis ,Biological sciences - Abstract
The life cycle of Bacillus anthracis includes both vegetative and endospore morphologies which alternate based on nutrient availability, and there is considerable evidence indicating that the ability of this organism to cause anthrax depends on its ability to progress through this life cycle in a regulated manner. Here we report the use of a custom B. anthracis GeneChip in defining the gene expression patterns that occur throughout the entire life cycle in vitro. Nearly 5,000 genes were expressed in five distinct waves of transcription as the bacteria progressed from germination through sporulation, and we identified a specific set of functions represented within each wave. We also used these data to define the temporal expression of the spore proteome, and in doing so we have demonstrated that much of the spore's protein content is not synthesized de novo during sporulation but rather is packaged from preexisting stocks. We explored several potential mechanisms by which the cell could control which proteins are packaged into the developing spore, and our analyses were most consistent with a model in which B. anthracis regulates the composition of the spore proteome based on protein stability. This study is by far the most comprehensive survey yet of the B. anthracis life cycle and serves as a useful resource in defining the growth-phase-dependent expression patterns of each gene. Additionally, the data and accompanying bioinformatics analyses suggest a model for sporulation that has broad implications for B. anthracis biology and offer new possibilities for microbial forensics and detection.
- Published
- 2006
4. Genetic analysis of petrobactin transport in Bacillus anthracis
- Author
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Carlson, Paul E., Jr, Dixon, Shandee D., Janes, Brian K., Carr, Katherine A., Nusca, Tyler D., Anderson, Erica C., Keene, Sarra E., Sherman, David H., and Hanna, Philip C.
- Published
- 2010
- Full Text
- View/download PDF
5. The role of Bacillus anthracis germinant receptors in germination and virulence
- Author
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Carr, Katherine A., Lybarger, Suzanne R., Anderson, Erica C., Janes, Brian K., and Hanna, Philip C.
- Published
- 2010
- Full Text
- View/download PDF
6. Transcriptional Profiling of Bacillus anthracis Sterne (34F2) during Iron Starvation.
- Author
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Carlson Jr., Paul E., Carr, Katherine A., Janes, Brian K., Anderson, Erica C., and Hanna, Philip C.
- Subjects
BACILLUS anthracis ,GENETIC regulation ,MICROBIAL virulence ,GENE expression ,SEPSIS ,PHAGOCYTES ,GENES ,REPLICATION (Experimental design) ,PATHOGENIC microorganisms - Abstract
Lack of available iron is one of many environmental challenges that a bacterium encounters during infection and adaptation to iron starvation is important for the pathogen to efficiently replicate within the host. Here we define the transcriptional response of B. anthracis Sterne (34F
2 ) to iron depleted conditions. Genome-wide transcript analysis showed that B. anthracis undergoes considerable changes in gene expression during growth in iron-depleted media, including the regulation of known and candidate virulence factors. Two genes encoding putative internalin proteins were chosen for further study. Deletion of either gene (GBAA0552 or GBAA1340) resulted in attenuation in a murine model of infection. This attenuation was amplified in a double mutant strain. These data define the transcriptional changes induced during growth in low iron conditions and illustrate the potential of this dataset in the identification of putative virulence determinants for future study. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
7. Transcriptional profiling of Bacillus anthracis Sterne (34F2) during iron starvation.
- Author
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Carlson PE Jr, Carr KA, Janes BK, Anderson EC, and Hanna PC
- Subjects
- Animals, Bacterial Proteins genetics, Disease Models, Animal, Gene Deletion, Mice, Mice, Inbred DBA, Oligonucleotide Array Sequence Analysis, Reverse Transcriptase Polymerase Chain Reaction, Virulence genetics, Bacillus anthracis metabolism, Bacterial Proteins chemistry, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Iron chemistry, Transcription, Genetic
- Abstract
Lack of available iron is one of many environmental challenges that a bacterium encounters during infection and adaptation to iron starvation is important for the pathogen to efficiently replicate within the host. Here we define the transcriptional response of B. anthracis Sterne (34F(2)) to iron depleted conditions. Genome-wide transcript analysis showed that B. anthracis undergoes considerable changes in gene expression during growth in iron-depleted media, including the regulation of known and candidate virulence factors. Two genes encoding putative internalin proteins were chosen for further study. Deletion of either gene (GBAA0552 or GBAA1340) resulted in attenuation in a murine model of infection. This attenuation was amplified in a double mutant strain. These data define the transcriptional changes induced during growth in low iron conditions and illustrate the potential of this dataset in the identification of putative virulence determinants for future study.
- Published
- 2009
- Full Text
- View/download PDF
8. Transcriptional profiling of Bacillus anthracis during infection of host macrophages.
- Author
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Bergman NH, Anderson EC, Swenson EE, Janes BK, Fisher N, Niemeyer MM, Miyoshi AD, and Hanna PC
- Subjects
- Animals, Anthrax microbiology, Bacillus anthracis genetics, Bacillus anthracis growth & development, Bacillus anthracis metabolism, Bacterial Proteins genetics, Cell Line, Humans, Mice, Mice, Inbred DBA, RNA, Bacterial analysis, RNA, Bacterial isolation & purification, Reverse Transcriptase Polymerase Chain Reaction, Trachea microbiology, Virulence, Bacillus anthracis pathogenicity, Bacterial Proteins metabolism, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Macrophages microbiology, Oligonucleotide Array Sequence Analysis methods, Transcription, Genetic
- Abstract
The interaction between Bacillus anthracis and the mammalian phagocyte is one of the central stages in the progression of inhalational anthrax, and it is commonly believed that the host cell plays a key role in facilitating germination and dissemination of inhaled B. anthracis spores. Given this, a detailed definition of the survival strategies used by B. anthracis within the phagocyte is critical for our understanding of anthrax. In this study, we report the first genome-wide analysis of B. anthracis gene expression during infection of host phagocytes. We developed a technique for specific isolation of bacterial RNA from within infected murine macrophages, and we used custom B. anthracis microarrays to characterize the expression patterns occurring within intracellular bacteria throughout infection of the host phagocyte. We found that B. anthracis adapts very quickly to the intracellular environment, and our analyses identified metabolic pathways that appear to be important to the bacterium during intracellular growth, as well as individual genes that show significant induction in vivo. We used quantitative reverse transcription-PCR to verify that the expression trends that we observed by microarray analysis were valid, and we chose one gene (GBAA1941, encoding a putative transcriptional regulator) for further characterization. A deletion strain missing this gene showed no phenotype in vitro but was significantly attenuated in a mouse model of inhalational anthrax, suggesting that the microarray data described here provide not only the first comprehensive view of how B. anthracis survives within the host cell but also a number of promising leads for further research in anthrax.
- Published
- 2007
- Full Text
- View/download PDF
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