Unique Biological Activity of Botulinum D/C Mosaic Neurotoxin in Murine Species

Abstract

cClostridium 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 vesicleassociated 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.

Purification and Characterization of Recombinant Botulinum Neurotoxin Serotype FA, Also Known as Serotype H

“…The mosaic structure of BoNT/FA combines an F5 family LC protease subunit with an A1 family H cc cell-binding domain and may confer unanticipated and potentially therapeutically valuable properties to this neurotoxin. Other naturally occurring mosaic BoNTs, such as BoNT/DC, have characteristics that are different from the constituent serotypes [ 43 , 44 ]. Similarly, engineered recombinant mosaic toxins that combine domains from BoNT/A with BoNT/E or BoNT/B have characteristics such as potency, toxicity and duration of action not predicted from those of their constituent serotypes [ 45 , 46 ].…”

CRISPR/Cas9-Mediated Genomic Deletion of the Beta-1, 4 N-acetylgalactosaminyltransferase 1 Gene in Murine P19 Embryonal Carcinoma Cells Results in Low Sensitivity to Botulinum Neurotoxin Type C

“…Gangliosides are required as a receptor component for BoNTs [ 1 ]. Using thin layer chromatography, BoNT/C was shown to bind to gangliosides GD1a, GD1b, and GT1b [ 12 , 21 ]. We investigated the selectivity and specificity of H C /C ganglioside recognition using SPR analysis because the affinity of H C /C to gangliosides remains unclear ( Fig 1 ).…”

Involvement of aph(3′)-IIa in the formation of mosaic aminoglycoside resistance genes in natural environments

“…BLAST search of GenBank revealed only a limited number of aph(3′)-IIa variants with sequence identities between 60 and 99%. This is in contrast to the many mosaic genes coding for penicillin binding proteins or tetracycline resistance determinants for which homologs with a continuous spectrum of sequence identity between 80 and 99% have been identified (Spratt, 1994 ; Oggioni et al, 1996 ; Hakenbeck, 2000 ; Hollingshead et al, 2000 ; Johansen et al, 2001 ; Prudhomme et al, 2002 ; Nakamura et al, 2012 ).…”