MOLECULAR COMPOSITION OF THE 16S TOXIN PRODUCED BY A CLOSTRIDIUM-BOTULINUM TYPE-D STRAIN, 1873

The 16S toxin was purified from a Clostridium botulinum type D strain 1873 (D-1873), Furthermore, the entire nucleotide sequences of the gen es coding for the 16S toxin were determined. It became clear that the purified D-1873 16S toxin consists of neurotoxin, nontoxic nonhemagglu tinin (NTNH), and hemagglutinin (HA), and that HA consists of four sub components, HA1, HA2, HA3a, and HA3b, the same as type D strain CB16 ( D-CB16) 16S toxin. The nucleotide sequences of the nontoxic components of these two strains were also found to be identical except for sever al bases. However, the culture supernatant and the purified 16S toxin of D-1873 showed little HA activity, unlike D-CB16, though the fractio ns successively eluted after the D-1873 16S toxin peak from an SP-Toyo pearl 650S column showed a low level of HA activity. The main differen ce between D-1873 and D-CB16 HA molecules was the mobility of the HA1 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE ). Therefore it was presumed that the loss of HA activity of D-1873 16 S toxin might be caused by the differences of processing HA after the translation.