Bacillus anthracis, the causative agent of anthrax, is a spore-forming organism. The ability to prepare anthrax spores inexpensively and deliver them in an aerosol form, and the high mortality rate of inhalation anthrax, have made B. anthracis one of the most dreaded agents of biowarfare and bioterrorism. This bacterium encodes two toxins, lethal toxin (LF) and edema toxin (EF), which are collectively called """"""""anthrax toxin"""""""" (AT). Lethal toxin is assembled from protective antigen (PA, 83 kDa) and lethal factor (LF, 90 kDa), and as its name implies, is primarily responsible for lethality from anthrax. Edema toxin is assembled from PA and Edema Factor (EF, 89 kDa), and has as its gross manifestation edema at the site of injection. Uptake of each of these toxins is critically dependent upon interaction of PA with its cellular receptor, which leads to receptor-mediated endocytosis followed by toxin translocation into the cytosol across the membrane of an acidic pH endosome. However, the precise understanding of how these toxins are taken up into cells, and the ability to intervene therapeutically in this process, has been severely impaired by not knowing the identity of the PA receptor. Therefore, the primary goal of the proposed research is to isolate and characterize the cellular receptor for PA. To this end, the applicant will use a genetic complementation approach that employs, as recipient cells, mutant CHO-K1 cell lines generated by the applicant and then subjected to a selection protocol to identify those lacking PA receptors. Once this receptor has been identified, the applicant will localize the PA binding domain, characterize the nature of its binding interaction with PA, and attempt to define the minimal cellular components required for AT assembly and translocation across membranes. The applicant will also determine how this receptor is taken up into cells after PA binding and oligomerization, by defining determinants of the receptor and cellular factors that are required for this process. Libraries of chemical compounds will be screened for effective inhibitors of the early steps of AT uptake and translocation. Collectively, these studies will significantly increase the knowledge of how anthrax toxin is taken up into cells and should identify effective chemical inhibitors of this process for future drug development.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
7R01AI048489-05
Application #
6785804
Study Section
Special Emphasis Panel (ZAI1-EWS-M (M2))
Program Officer
Baker, Phillip J
Project Start
2000-08-15
Project End
2004-06-30
Budget Start
2003-08-01
Budget End
2004-06-30
Support Year
5
Fiscal Year
2003
Total Cost
$449,673
Indirect Cost
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
078731668
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Reeves, C V; Dufraine, J; Young, J A T et al. (2010) Anthrax toxin receptor 2 is expressed in murine and tumor vasculature and functions in endothelial proliferation and morphogenesis. Oncogene 29:789-801
Ryan, Patricia L; Young, John A T (2008) Evidence against a human cell-specific role for LRP6 in anthrax toxin entry. PLoS One 3:e1817
Scobie, Heather M; Marlett, John M; Rainey, G Jonah A et al. (2007) Anthrax toxin receptor 2 determinants that dictate the pH threshold of toxin pore formation. PLoS One 2:e329
Sun, Jianjun; Vernier, Gregory; Wigelsworth, Darran J et al. (2007) Insertion of anthrax protective antigen into liposomal membranes: effects of a receptor. J Biol Chem 282:1059-65
Scobie, Heather M; Wigelsworth, Darran J; Marlett, John M et al. (2006) Anthrax toxin receptor 2-dependent lethal toxin killing in vivo. PLoS Pathog 2:e111
Keim, Paul; Mock, Michele; Young, John et al. (2006) The International Bacillus anthracis, B. cereus, and B. thuringiensis Conference, ""Bacillus-ACT05"". J Bacteriol 188:3433-41
Scobie, Heather M; Young, John A T (2005) Interactions between anthrax toxin receptors and protective antigen. Curr Opin Microbiol 8:106-12
Rainey, G Jonah A; Wigelsworth, Darran J; Ryan, Patricia L et al. (2005) Receptor-specific requirements for anthrax toxin delivery into cells. Proc Natl Acad Sci U S A 102:13278-83
Lacy, D Borden; Wigelsworth, Darran J; Scobie, Heather M et al. (2004) Crystal structure of the von Willebrand factor A domain of human capillary morphogenesis protein 2: an anthrax toxin receptor. Proc Natl Acad Sci U S A 101:6367-72
Lacy, D Borden; Wigelsworth, Darran J; Melnyk, Roman A et al. (2004) Structure of heptameric protective antigen bound to an anthrax toxin receptor: a role for receptor in pH-dependent pore formation. Proc Natl Acad Sci U S A 101:13147-51

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