These recent experimental results extend and explain a 1999 discovery by the Collier lab identifying a set of mutations in protective antigen that prevent translocation, some of which represented a new type of antitoxin that may be useful in anthrax treatment.
In the recent work, Collier and his colleagues found that the phi-clamp composes the main conductance-blocking site for hydrophobic drugs, and it is one of their targets for further investigation. "I believe discovery of the phi-clamp will prove to be one of the high points along the path to understanding how translocation occurs in this system," Collier said.
One of the greatest strengths of the experiment, according to Collier, was the integrative use of technologies applied to the testing procedures. Both cellular systems and model electrophysiological membrane systems were used to test the potency of the anthrax toxin. "We tried to bridge reductionist science with the in vivo situation ?we have to do both to make correlations," he said.
The researchers, who were funded by the National Institutes of Health and the National Science Foundation, will continue to study protein unfolding in translocation during anthrax infection, which may prove to be relevant in other biological systems. "This is only a partial picture," Collier said. "There are still major outstanding questions about the overall process that need to be addressed."