Molecular composition of progenitor toxin produced by Clostridium botulinum type C strain 6813

The molecular composition of the purified progenitor toxin produced by a Cl ostridium botulinum type C strain 6813 (C-6813) was analyzed. The strain pr oduced two types of progenitor toxins (M and L). Purified L toxin is formed by conjugation of the M toxin (composed of a neurotoxin and a non-toxic no nhemagglutinin) with additional hemagglutinin (HA) components. The dual cle avage sites at loop region of the dichain structure neurotoxin were identif ied between Arg444-Ser445 and Lys449-Thr450 by the analyses of C-terminal o f the light chain and N-terminal of the heavy chain. Analysis of partial am ino acid sequences of fragments generated by limited proteolysis of the neu rotoxin has shown to that the neurotoxin protein produced by C-6813 was a h ybrid molecule composed of type C and D neurotoxins as previously reported. HA components consist of a mixture of several subcomponents with molecular weights of 70-, 55-, 33-, 26 similar to 21- and 17-kDa. The N-terminal ami no acid sequences of 70-, 55-, and 26 similar to 21-kDa proteins indicated that the 70-kDa protein was intact HA-70 gene product, and other 55- and 26 similar to 21-kDa proteins were derived from the 70-kDa protein by modific ation with proteolysis after translation of HA-70 gene. Furthermore, severa l amino acid differences were exhibited in the amino acid sequence as compa red with the deduced sequence from the nucleotide sequence of the HA-70 gen e which was common among type C (strains C-St and C-468) and D progenitor t oxins (strains D-CB16 and D-1873).