Characterization of Clostridium botulinum type B neurotoxin associated with infant botulism in japan.
The neurotoxin of strain 111 (111/NT) associated with type B infant botulism showed antigenic and biological properties different from that (Okra/NT) produced by a food-borne botulism-related strain, Okra. The specific toxicity of 111/NT was found to be about 10 times lower than that of Okra/NT. The monoclonal antibodies recognizing the light chain cross-reacted with both neurotoxins, whereas most of the antibodies recognizing the carboxyl-terminal half of the heavy chain of Okra/NT did not react to 111/NT. Binding experiments with rat brain synaptosomes revealed that 125I-labeled 111/NT bound to a single binding site with a dissociation constant (Kd) of 2.5 nM; the value was rather lower than that (0.42 nM) of 125I-Okra/NT for the high-affinity binding site. In the lipid vesicles reconstituted with ganglioside GT1b, 125I-Okra/NT interacted with the amino-terminal domain of synaptotagmin 1 (Stg1N) or synaptotagmin 2 (Stg2N), fused with the maltose-binding protein, in the same manner as the respective full-length synaptotagmins, and the Kd values accorded with those of the low- and high-affinity binding sites in synaptosomes. However, 125I-111/NT only exhibited a low capacity for binding to the lipid vesicles containing Stg2N, but not Stg1N, in the presence of ganglioside GT1b. Moreover, synaptobrevin-2, an intracellular target protein, was digested to the same extent by the light chains of both neurotoxins in a concentration-dependent manner. These findings indicate that the 111/NT molecule possesses the receptor-recognition site structurally different from Okra/NT, probably causing a decreased specific toxicity.
Kozaki
S
S
Department of Veterinary Science, College of Agriculture, Osaka Prefecture University, Sakai, Osaka, Ishikawa, Japan. kozaki@center.osakafu-u.ac.jp
Kamata
Y
Y
Nishiki
T
T
Kakinuma
H
H
Maruyama
H
H
Takahashi
H
H
Karasawa
T
T
Yamakawa
K
K
Nakamura
S
S
D000818:Animals; D001905:Botulinum Toxins / Q000276:immunology / Q000378:metabolism / Q000633:toxicity*; D019274:Botulinum Toxins, Type A; D001906:Botulism / Q000453:epidemiology / Q000382:microbiology*; D002135:Calcium-Binding Proteins; D003014:Clostridium botulinum / Q000472:pathogenicity*; D006801:Humans; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008666:Metalloendopeptidases / Q000276:immunology / Q000378:metabolism / Q000633:toxicity*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009498:Neurotoxins / Q000276:immunology / Q000378:metabolism / Q000633:toxicity*; D011485:Protein Binding; D050683:R-SNARE Proteins; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism; D050863:Synaptotagmin I; D050857:Synaptotagmins
D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009498:Neurotoxins; D050683:R-SNARE Proteins; D011994:Recombinant Proteins; C494310:SYT1 protein, human; D050863:Synaptotagmin I; C494312:Syt1 protein, rat; C096323:rimabotulinumtoxinB; D050857:Synaptotagmins; D008666:Metalloendopeptidases; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A