Anthrax Pore formation

Anthrax toxin is a bacterial toxin from Bacillus anthracis consisting of three parts protective antigen (PA), lethal factor (LF) and edema factor (EF). Both LF and EF compete for binding sites on the PA protein. The PA protein binds with high affinity to an as yet unknown receptor on macrophages and related cell types. When PA is internalized by the target cells, it functions as a shuttle protein for either EF or LF. Intracellularly, in the acidic environment of the endosome, EF and LF are capable of entering the cytosol by pH-dependent pore formation [139]. 

Carboxy (C)-terminal end involved in recognition and binding to the anthrax toxin receptor of susceptible host cells as well as pore formation... 

Wimalaseiia, D.S., Janowiak, B.E., Lovell, S., et al. (2010) Evidence that histidine protonation of receptor-bound anthrax protective antigen is a trigger for pore formation. Biochemistry, 49 (33), 6973-6983. Sawaya, M.R., Kraut, J. (1997) Loop and subdomain movements in the mechanism of Escherichia coli dihydrofolate reductase Crysttillographic evidence. Biochemistry, 36 (3), 586-603. 

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