[The structure and function of botulinum type C neurotoxin].

The structure gene for botulinum type C neurotoxin was cloned from the toxigenic bacteriophage obtained from Clostridium botulinum type C, and the whole nucleotide sequence was determined. The nucleotide sequence contained a single open reading frame coding for 1,291 amino acids corresponding to a polypeptide with a molecular weight of 149,000. The signal peptide was not found after the first methionine residue. Upstream of the ATG codon, sequences predicted as a Shine-Dalgarno and a promoter were found. When the deduced amino acid sequence of type C toxin was compared with those of type A and D botulinum toxins and tetanus toxin, type C toxin shared about 52% identity with type D toxin, but shared only about 33% identity with type A and tetanus toxins. The structure and function of type C toxin were estimated from the results of epitope map with monoclonal antibodies and DNA thermal stability map.