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)
References:
CTX of phage φCTX of Pseudomonas aeruginosa
Uncharacterized protein of 285 aas
Proteobacteria
UP of Pectobactyerium wasabiae
Cytotoxic Leucocidin of 290 aas
Bacteroidetes
Cytotoxic leucocidin of Fibrella aestuarina
Uncharacterized protein with similarity to clostridial epsilon toxin ETX and Bacillus mosquitocidal toxin MTX2.
Proteobacteria
UP of Virbio caribbenthicus
Arthropod secreted salivary gland protein of 278 aas
Animals
Secreted protein of Ixodes scapularis
Secreted salivary gland protein of 291 aas.
Alveolata
Secreted protein of Oxytricha trifallax