Interactions of anthrax lethal factor with protective antigen defined by site-directed spin labeling
Laura D Jennings-Antipov1, Likai Song, R John Collier
1Department of Microbiology and Molecular Genetics and Medicine, Harvard Medical School, Boston, MA 02115, USA.
Summary
Anthrax toxin
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Anthrax toxin's protective antigen (PA) forms pores for lethal factor (LF) and edema factor (EF) translocation.
- Understanding PA-LF interactions is crucial for toxin mechanism elucidation.
Purpose of the Study:
- To identify specific interaction sites between LF and PA in its prepore and pore conformations.
- To elucidate the structural basis of LF translocation through the PA pore.
Main Methods:
- Site-directed spin-labeling studies.
- Analysis of protein-protein interactions in anthrax toxin.
Main Results:
- Identified direct interaction between LF N-terminus (residues 2-5) and the PA pore's Φ-clamp.
- Observed LF helix α1 separating and binding to the PA α-clamp upon substrate binding.
- Confirmed LF interacts with the PA pore at three distinct sites, including domain 1' of PA.
Conclusions:
- Elucidated the specific molecular interactions governing LF translocation.
- Provided structural insights into the mechanism of anthrax toxin entry into mammalian cells.
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