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YEAR : 2021

The protein-binding pocket of Botulinum neurotoxin B accommodates a preassembled synaptotagmin / ganglioside complex

AUTHORS : Ramirez-Franco JJ, Azzaz F, Sangiardi M, Ferracci Géraldine, Youssouf F, Popoff Michel Robert, Seagar M, Lévêque C, Fantini J, El Far O.

N° Pubmed : doi:
Botulinum neurotoxin serotype B (BoNT/B) uses two separate protein and polysialoglycolipid-binding pockets to interact with synaptotagmin 1/2 and gangliosides. However, an integrated model of BoNT/B bound to its neuronal receptors in a native membrane topology is still lacking. Using a panel of in silico and experimental approaches, we present here a new model for BoNT/B binding to neuronal membranes, in which the toxin binds to a preassembled synaptotagmin-ganglioside GT1b complex and a free ganglioside. This interaction allows a lipid-binding loop of BoNT/B to engage in a series of concomitant interactions with the glycone part of GT1b and the transmembrane domain of synaptotagmin. Furthermore, our data provide molecular support for the decrease in BoNT/B sensitivity in Felidae that harbor the natural variant synaptotagmin2-N59Q. These results reveal multiple interactions of BoNT/B with gangliosides and support a novel paradigm in which a toxin recognizes a protein/ganglioside complex.