1.C.13 The Channel-forming Leukocidin Cytotoxin (Ctx) Family

A single protein, Ctx of phage φCTX of Pseudomonas aeruginosa comprises the Ctx family. The cytotoxin is believed to form hydrophilic pores in target cell membranes. The inactive, cell associated (non-secreted) precursor is converted to the active toxin by protease digestion at the same time that P. aeruginosa lyses. Leukocidin (cytotoxin) is active against most eukaryotic cells, especially leukocytes. It exhibits a short region similar to corresponding regions in α-toxin from Staphylococcus aureus and aerolysin from Aeromonas species (residues 222-251). The soluble secreted protein inserts into the target cell membrane and probably forms a pentameric pore-forming structure.

The generalized transport reaction is:

Ions (in) ions (out)