Bacillus anthracis is the etiological agent of
anthrax and the bacterium produces a tripartite
anthrax toxin composed of protective
antigen (PA), lethal factor (LF) and
edema factor (EF). PA represents the binding domain of the toxin and acts in concert with either LF, a
metalloprotease, or EF, an
adenylate cyclase, to form lethal toxin (LeTx) or
edema toxin (EdTx), respectively. We analyzed the proteomics response of two murine macrophage cell lines (J774.1A and RAW264.7) following B. anthracis LeTx treatment to detect unique host
proteins involved in
anthrax infection using difference in-gel electrophoresis (DIGE) followed by nanoLC-MS for identification of the
proteins. The comparative proteomics approach identified a set of
proteins in each cell line that was consistently upregulated when the two macrophage cell lines were treated with LeTx. The upregulated
proteins include those involved in energy metabolism, cytoskeleton structure and stress response. A subset of five
proteins (
ATP synthase beta subunit,
beta-actin, Hsp70,
vimentin, and Hsp60 homolog) was identified that were commonly upregulated in both cell lines. The proteomic data suggest the involvement of
reactive oxygen species (ROS) in cell lysis as seen by the upregulation of
proteins that lead to the production of ROS in both the cell lines used in our study. However,
proteins that afford protection against ROS may play an important role in the survival of the macrophage to LeTx
infection as shown by the differences in proteomic responses of the two cell lines to the action of LeTx. These identified
proteins may have the potential to be used as
biomarkers for diagnostics and
therapeutics.