title: Botulinum neurotoxin D-C uses synaptotagmin I and II as receptors, and human synaptotagmin II is not an effective receptor for type B, D-C and G toxins.
abstract: Botulinum neurotoxins (BoNTs) are classified into seven types (A-G), but multiple subtype and mosaic toxins exist. These subtype and mosaic toxins share a high sequence identity, and presumably the same receptors and substrates with their parental toxins. Here, we report that a mosaic toxin, type D-C (BoNT/D-C), uses different receptors from its parental toxin BoNT/C. BoNT/D-C, but not BoNT/C, binds directly to the luminal domains of synaptic vesicle proteins synaptotagmin (Syt) I and II, and requires expression of SytI/II to enter neurons. The SytII luminal fragment containing the toxin-binding site can block the entry of BoNT/D-C into neurons and reduce its toxicity in vivo in mice. We also found that gangliosides increase binding of BoNT/D-C to SytI/II and enhance the ability of the SytII luminal fragment to block BoNT/D-C entry into neurons. These data establish SytI/II, in conjunction with gangliosides, as the receptors for BoNT/D-C, and indicate that BoNT/D-C is functionally distinct from BoNT/C. We further found that BoNT/D-C recognizes the same binding site on SytI/II where BoNT/B and G also bind, but utilizes a receptor-binding interface that is distinct from BoNT/B and G. Finally, we also report that human and chimpanzee SytII has diminished binding and function as the receptor for BoNT/B, D-C and G owing to a single residue change from rodent SytII within the toxin binding site, potentially reducing the potency of these BoNTs in humans and chimpanzees.
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School and Division of Neuroscience, New England Primate Research Center, Southborough, MA 01772, USA.
authors.forename: Lisheng
authors.initials: L
authors.lastname: Peng
authors.forename: Ronnie P-A
authors.initials: RP
authors.lastname: Berntsson
authors.forename: William H
authors.initials: WH
authors.lastname: Tepp
authors.forename: Rose M
authors.initials: RM
authors.lastname: Pitkin
authors.forename: Eric A
authors.initials: EA
authors.lastname: Johnson
authors.forename: Pål
authors.initials: P
authors.lastname: Stenmark
authors.forename: Min
authors.initials: M
authors.lastname: Dong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001905:Botulinum Toxins / Q000378:metabolism*; D019274:Botulinum Toxins, Type A; D002478:Cells, Cultured; D003014:Clostridium botulinum / Q000378:metabolism; D005089:Exocytosis; D006624:Hippocampus / Q000166:cytology; D006801:Humans; D007928:Lethal Dose 50; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism; D050863:Synaptotagmin I / Q000378:metabolism*; D050861:Synaptotagmin II / Q000378:metabolism*
chemical_list: D011956:Receptors, Cell Surface; C494262:SYT2 protein, human; D050863:Synaptotagmin I; D050861:Synaptotagmin II; C494312:Syt1 protein, rat; C096323:rimabotulinumtoxinB; C488535:botulinum toxin type G; C096325:botulinum toxin type D; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A; C096324:botulinum toxin type C