Protective Antigen (PA) is the receptor-binding component of the anthrax toxin that plays a pivotal role in the translocation of the anthrax enzymatic components, Lethal Factor (LF) and Edema Factor (EF) into host cells. PA forms a non-constitutive b-barrel pore in endosomal membranes by a process that involves its intermolecular interactions with its receptor (ANTXR1 or ANTXR2) at acidic pH. Our main objective of this grant application is to understand the poorly defined structural and dynamic interactions between PA and its target receptor that lead to pore formation. To accomplish these goals, we intend to study the membrane inserted pore and the interaction of PA with its receptor at atomic resolution using a combination of nuclear magnetic resonance (NMR) and biochemical techniques. Using these procedures, we will (1) solve the high- resolution structure of the PA pore formed within micelles, (2) evaluate the dynamics of the heptameric PA that leads to pore formation at a range of different pH values, and (3) examine the structural and dynamic changes that govern the PA:receptor complex as it enters into a low pH environment. The results of our investigation will provide the basis for understanding the structural rearrangements of the PA:receptor complex that lead to pore formation, and give insights into the translocation process with the atomic details of the heptameric pore. Results of these studies will be the foundation for the rational basis for designing novel therapeutics to block anthrax toxin pore formation and translocation into cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32AI082935-02
Application #
8043530
Study Section
Special Emphasis Panel (ZRG1-F13-C (20))
Program Officer
Breen, Joseph J
Project Start
2009-02-01
Project End
2012-01-31
Budget Start
2010-02-01
Budget End
2011-01-31
Support Year
2
Fiscal Year
2010
Total Cost
$47,606
Indirect Cost
Name
Salk Institute for Biological Studies
Department
Type
DUNS #
078731668
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Pilpa, Rosemarie M; Bayrhuber, Monika; Marlett, John M et al. (2011) A receptor-based switch that regulates anthrax toxin pore formation. PLoS Pathog 7:e1002354