CytK toxin of Bacillus cereus forms pores in planar lipid bilayers and is cytotoxic to intestinal epithelia

CytK is a cytotoxin isolated from a strain of Bacillus cereus cultured from cases of necrotic enteritis and the amino acid sequence of the protein sug gests that it may belong to the family of beta -barrel pore-forming toxins. We show here in planar lipid bilayers the toxin is able to form pores whic h are weakly anion selective and exhibit an open channel probability close to one. The predicted minimum pore diameter is approximately 7 Angstrom. We also show that cytK is a potent cytotoxin against human intestinal Caco-2 epithelia. CytK. like other beta -barrel pore-forming toxins, spontaneously Forms oligomers which are resistant to sodium dodecyl sulphate (SDS), but not to boiling. CytK represents a pore-forming toxin linked with human case s of necrotic enteritis. (C) 2001 Federation of European Microbiological So cieties. Published by Elsevier Science B.V. All rights reserved.