Transcriptional profiling of the clpX mutant in Bacillus anthracis reveals regulatory connection with the lrgAB operon

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.

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Transcriptional profiling of murine organ genes in response to infection with Bacillus anthracis Ames spores

Microbial Pathogenesis ◽

10.1016/j.micpath.2007.10.004 ◽

2008 ◽

Vol 44 (4) ◽

pp. 293-310 ◽

Cited By ~ 7

Author(s):

Scott T. Moen ◽

Linsey A. Yeager ◽

William S. Lawrence ◽

Cindy Ponce ◽

Cristi L. Galindo ◽

...

Keyword(s):

Bacillus Anthracis ◽

Transcriptional Profiling

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Transcriptional Profiling of Human Peripheral Blood Mononuclear Cells Exposed to Bacillus anthracis in vitro

Journal of Bioterrorism & Biodefense ◽

10.4172/2157-2526.s3-014 ◽

2013 ◽

Vol 01 (S3) ◽

Author(s):

Rasha Hammamieh

Keyword(s):

Bacillus Anthracis ◽

Peripheral Blood Mononuclear Cells ◽

Peripheral Blood ◽

Mononuclear Cells ◽

Human Peripheral Blood ◽

Transcriptional Profiling ◽

Peripheral Blood Mononuclear ◽

Blood Mononuclear Cells

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Global Effects of Virulence Gene Regulators in a Bacillus anthracis Strain with Both Virulence Plasmids

Infection and Immunity ◽

10.1128/iai.71.5.2736-2743.2003 ◽

2003 ◽

Vol 71 (5) ◽

pp. 2736-2743 ◽

Cited By ~ 104

Author(s):

Agathe Bourgogne ◽

Melissa Drysdale ◽

Susan G. Hilsenbeck ◽

Scott N. Peterson ◽

Theresa M. Koehler

Keyword(s):

Bacillus Anthracis ◽

Gene Transcription ◽

Target Genes ◽

Transcriptional Profiling ◽

Virulence Gene ◽

Regulatory Genes ◽

Negative Effects ◽

Virulence Plasmids ◽

Chromosomal Genes ◽

A Minor

ABSTRACT Control of anthrax toxin and capsule synthesis, the two major virulence factors of Bacillus anthracis, has been associated with two regulatory genes, atxA and acpA, located on virulence plasmids pXO1 and pXO2, respectively. We used transcriptional profiling to determine whether atxA and/or acpA control genes other than those already described and to investigate functional similarities of the regulators. Transcription was assessed in a pXO1+ pXO2+ parent strain and in isogenic mutants in which one or both regulatory genes were deleted. We determined that in addition to the toxin and capsule genes, atxA controls expression of numerous other genes on both plasmids and the chromosome. Generally, plasmid-encoded genes were more highly regulated than chromosomal genes, and both positive and negative effects were observed. Certain atxA-regulated genes were affected synergistically in an atxA acpA mutant. Yet overall, acpA appears to be a minor regulator with fewer targets than atxA. In contrast to previous reports of acpA function in attenuated strains, acpA had a minimal influence on capsule gene transcription and capsule synthesis in a genetically complete strain. Surprisingly, acpA expression was positively affected by atxA, although atxA-activated capsule gene transcription is not acpA dependent. The newly discovered atxA-regulated targets include genes predicted to encode secreted proteins and proteins with roles in transcriptional regulation and signaling. Regulation of chromosomal genes by atxA is particularly intriguing, given that many of the target genes have homologues in other Bacillus species that lack atxA homologues. Given the global effect of atxA on gene expression in B. anthracis, previous assumptions regarding reduced virulence of strains harboring single plasmids must be reassessed and the potential roles of newly identified atxA-regulated genes should be investigated.

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Transcriptional Profiling of the Bacillus anthracis Life Cycle In Vitro and an Implied Model for Regulation of Spore Formation

Journal of Bacteriology ◽

10.1128/jb.00723-06 ◽

2006 ◽

Vol 188 (17) ◽

pp. 6092-6100 ◽

Cited By ~ 64

Author(s):

Nicholas H. Bergman ◽

Erica C. Anderson ◽

Ellen E. Swenson ◽

Matthew M. Niemeyer ◽

Amy D. Miyoshi ◽

...

Keyword(s):

Life Cycle ◽

Bacillus Anthracis ◽

De Novo ◽

Transcriptional Profiling ◽

Expression Patterns ◽

Temporal Expression ◽

Bioinformatics Analyses ◽

Microbial Forensics ◽

Comprehensive Survey

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.

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