Anthrax toxin takes charge

Bacterial toxin proteins are generally thought to enter eukaryotic cells by passive hitchhiking, binding to a convenient receptor that is constitutively internalized by endocytosis to ensure their delivery to the cytoplasm. But on page 321, Abrami et al. show that, at least in the case of anthrax, the toxin precisely choreographs its uptake by hijacking a specific endocytic pathway. The work suggests a possible strategy for treating anthrax infections and also highlights a connection between raft-mediated and clathrin-dependent endocytosis, two pathways that were once considered to be mutually exclusive.

Bacillus anthracis produces a toxin with three subunits. After binding to the cellular anthrax toxin receptor, a transmembrane protein of unknown function, the protective antigen subunit undergoes cleavage and heptamerization and then binds to the lethal factor and edema factor subunits to carry the...