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Structures and targets of the anthrax bacterium
  
By
Edward R. Winstead



Two scientific papers on the anthrax bacterium Bacillus anthracis provide information about the pathogen's structure and how it engages human cells.


Stereo ribbon representation of lethal factor enzyme. View larger

In one paper, researchers identify the initial target of the anthrax toxin in humans—a receptor on the surface of cells. Once the bacterium has invaded the body, it secretes a three-part toxin, and one part binds to the receptor on human cells. This binding allows the other two parts of the toxin to enter the cell and begin destroying their surroundings.

"The identification of [the receptor for the anthrax protein] now allows for a more detailed investigation of the mechanism of uptake by cells of anthrax toxin," write John A. T. Young, of the University of Wisconsin-Madison, and colleagues.

In the second paper, researchers report the three-dimensional structure of another part of the toxin, called lethal factor. This enzyme disrupts communication within immune cells, inhibiting a response. Cells eventually rupture, which causes shock, a loss of blood pressure, and death.

The study was done by Robert Liddington, of The Burnham Institute in La Jolla, California, and colleagues. They are using the information to try to develop ways to block lethal factor.

Because of interest in the subject, the papers were published online in advance of their print publication next month in Nature.

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Bradley, K.A. et al. Identification of the cellular receptor for anthrax toxin. Nature 414 (November 8, 2001). Published online October 23, 2001.
 
Pannifer, A.D. et al. Crystal structure of the anthrax lethal factor. Nature 414 (November 8, 2001). Published online October 23, 2001.
 

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