Unique biological activity of botulinum D/C mosaic neurotoxin in murine species.
Clostridium botulinum types C and D cause animal botulism by the production of serotype-specific or mosaic botulinum neurotoxin (BoNT). The D/C mosaic BoNT (BoNT/DC), which is produced by the isolate from bovine botulism in Japan, exhibits the highest toxicity to mice among all BoNTs. In contrast, rats appeared to be very resistant to BoNT/DC in type C and D BoNTs and their mosaic BoNTs. We attempted to characterize the enzymatic and receptor-binding activities of BoNT/DC by comparison with those of type C and D BoNTs (BoNT/C and BoNT/D). BoNT/DC and D showed similar toxic effects on cerebellar granule cells (CGCs) derived from the mouse, but the former showed less toxicity to rat CGCs. In recombinant murine-derived vesicle-associated membrane protein (VAMP), the enzymatic activities of both BoNTs to rat isoform 1 VAMP (VAMP1) were lower than those to the other VAMP homologues. We then examined the physiological significance of gangliosides as the binding components for types C and D, and mosaic BoNTs. BoNT/DC and C were found to cleave an intracellular substrate of PC12 cells upon the exogenous addition of GM1a and GT1b gangliosides, respectively, suggesting that each BoNT recognizes a different ganglioside moiety. The effect of BoNT/DC on glutamate release from CGCs was prevented by cholera toxin B-subunit (CTB) but not by a site-directed mutant of CTB that did not bind to GM1a. Bovine adrenal chromaffin cells appeared to be more sensitive to BoNT/DC than to BoNT/C and D. These results suggest that a unique mechanism of receptor binding of BoNT/DC may differentially regulate its biological activities in animals.
Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan. k-nakamura@vet.osakafu-u.ac.jp
Keiji
K
Nakamura
Tomoko
T
Kohda
Yuto
Y
Shibata
Kentaro
K
Tsukamoto
Hideyuki
H
Arimitsu
Mitsunori
M
Hayashi
Masafumi
M
Mukamoto
Nobuyuki
N
Sasakawa
Shunji
S
Kozaki
D000311:Adrenal Glands / Q000166:cytology; D000818:Animals; D001905:Botulinum Toxins / Q000145:classification / Q000378:metabolism / Q000633:toxicity*; D002417:Cattle; D002531:Cerebellum / Q000166:cytology; D019439:Chromaffin Cells / Q000187:drug effects; D003014:Clostridium botulinum / Q000378:metabolism*; D005260:Female; D005732:Gangliosides / Q000378:metabolism; D051379:Mice; D009498:Neurotoxins / Q000145:classification / Q000378:metabolism / Q000633:toxicity*; D016716:PC12 Cells; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins; D013045:Species Specificity
D005732:Gangliosides; D009498:Neurotoxins; D011994:Recombinant Proteins; D001905:Botulinum Toxins