Hemagglutinin-33 in the neurotoxin complex of typec A Clostridium botulinum is a Heat Shock Protein

The response of Clostridium botulinum type A strain to elevated temperature was investigated with respect to its growth pattern, and qualitative and quantitative alterations in the protein profile. Transfer of the mid log phase cells from 37°C to 45°C repressed the synthesis of several cellular proteins and concomitantly, synthesis of some proteins including a 33 kDa polypeptide, was markedly enhanced. The induction and synthesis of 33 kDa protein was also observed in 2-D gel analysis of the cells grown at 37°C and 45°C. Immunoblot analysis revealed that 33 kDa protein is a hemagglutinin component of the neurotoxin complex of type A Clostridium botulinum. From these findings we conclude that the 33 kDa protein component of type A neurotoxin complex, known to protect and stabilise neurotoxins from a hostile environment, is a Heat Shock Protein (HSP).