BIOCHEMICAL AND IMMUNOLOGICAL PROPERTIES OF THE C-TERMINAL DOMAIN OF THE ALPHA-TOXIN OF CLOSTRIDIUM-PERFRINGENS

The C-terminal domain of the alpha-toxin (cpa247-370) of Clostridium p erfringens has been expressed in Escherichia coli and purified. Antise rum raised against cpa247-370 reacted in an identical manner to anti-a lpha-toxin serum when used to map epitopes in the C-terminal domain, s uggesting that cpa247-370 was immunologically and structurally identic al to this region in the alpha-toxin. The isolated cpa247-370 was devo id of sphingomyelinase activity or haemolytic activity and was not cyt otoxic for mouse lymphocytes. Haemolytic activity was detected when cp a247-370 was tested with the N-terminal domain of the alpha-toxin (cpa 1-249), confirming that cpa247-370 confers haemolytic properties on th e phospholipase C activity of the alpha-toxin. Haemolytic activity was not detected if cpa247-370 was tested with the Bacillus cereus phosph atidylcholine phospholipase C, nor if cpa1-249 and cpa247-370 were inc ubated sequentially with erythrocytes.