title: Synaptotagmins I and II act as nerve cell receptors for botulinum neurotoxin G.
abstract: Botulinum neurotoxins (BoNTs) induce muscle paralysis by selectively entering cholinergic motoneurons and subsequent specific cleavage of core components of the vesicular fusion machinery. Complex gangliosides are requisite for efficient binding to neuronal cells, but protein receptors are critical for internalization. Recent work evidenced that synaptotagmins I and II can function as protein receptors for BoNT/B (Dong, M., Richards, D. A., Goodnough, M. C., Tepp, W. H., Johnson, E. A., and Chapman, E. R. (2003) J. Cell Biol. 162, 1293-1303). Here, we report the protein receptor for a second BoNT serotype. Like BoNT/B, BoNT/G employs synaptotagmins I and II to enter phrenic nerve cells. Using pull-down assays we show that only BoNT/G, but neither the five remaining BoNTs nor tetanus neurotoxin, interacts with synaptotagmins I and II. In contrast to BoNT/B, interactions with both isoforms are independent of the presence of gangliosides. Peptides derived from the luminal domain of synaptotagmin I and II are capable of blocking the neurotoxicity of BoNT/G in phrenic nerve preparations. Pull-down and neutralization assays further established the membrane-juxtaposed 10 luminal amino acids of synaptotagmins I and II as the critical segment for neurotoxin binding. In addition, we show that the carboxyl-terminal domain of the cell binding fragment of BoNT/B and BoNT/G mediates the interaction with their protein receptor.
authors.affiliation: Institutes of Biochemistry and Toxicology, Medizinische Hochschule Hannover, D-30625 Hannover, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Rummel
authors.forename: Tino
authors.initials: T
authors.lastname: Karnath
authors.forename: Tina
authors.initials: T
authors.lastname: Henke
authors.forename: Hans
authors.initials: H
authors.lastname: Bigalke
authors.forename: Thomas
authors.initials: T
authors.lastname: Binz
mesh_terms: D000818:Animals; D001905:Botulinum Toxins / Q000737:chemistry* / Q000378:metabolism*; D019274:Botulinum Toxins, Type A; D002135:Calcium-Binding Proteins; D002462:Cell Membrane / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005732:Gangliosides / Q000737:chemistry; D005982:Glutathione Transferase / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D010791:Phrenic Nerve / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D050863:Synaptotagmin I; D050861:Synaptotagmin II; D050857:Synaptotagmins
chemical_list: D002135:Calcium-Binding Proteins; D005732:Gangliosides; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D050863:Synaptotagmin I; D050861:Synaptotagmin II; C494311:Syt1 protein, mouse; C494263:Syt2 protein, mouse; C096323:rimabotulinumtoxinB; D050857:Synaptotagmins; C488535:botulinum toxin type G; D005982:Glutathione Transferase; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A