title: Identification of the SV2 protein receptor-binding site of botulinum neurotoxin type E.
abstract: The highly specific binding and uptake of BoNTs (botulinum neurotoxins; A-G) into peripheral cholinergic motoneurons turns them into the most poisonous substances known. Interaction with gangliosides accumulates the neurotoxins on the plasma membrane and binding to a synaptic vesicle membrane protein leads to neurotoxin endocytosis. SV2 (synaptic vesicle glycoprotein 2) mediates the uptake of BoNT/A and /E, whereas Syt (synaptotagmin) is responsible for the endocytosis of BoNT/B and /G. The Syt-binding site of the former was identified by co-crystallization and mutational analyses. In the present study we report the identification of the SV2-binding interface of BoNT/E. Mutations interfering with SV2 binding were located at a site that corresponds to the Syt-binding site of BoNT/B and at an extended surface area located on the back of the conserved ganglioside-binding site, comprising the N- and C-terminal half of the BoNT/E-binding domain. Mutations impairing the affinity also reduced the neurotoxicity of full-length BoNT/E at mouse phrenic nerve hemidiaphragm preparations demonstrating the crucial role of the identified binding interface. Furthermore, we show that a monoclonal antibody neutralizes BoNT/E activity because it directly interferes with the BoNT/E-SV2 interaction. The results of the present study suggest a novel mode of binding for BoNTs that exploit SV2 as a cell surface receptor.
authors.affiliation: Institut für Biochemie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mahrhold
authors.forename: Jasmin
authors.initials: J
authors.lastname: Strotmeier
authors.forename: Consuelo
authors.initials: C
authors.lastname: Garcia-Rodriguez
authors.forename: Jianlong
authors.initials: J
authors.lastname: Lou
authors.forename: James D
authors.initials: JD
authors.lastname: Marks
authors.forename: Andreas
authors.initials: A
authors.lastname: Rummel
authors.forename: Thomas
authors.initials: T
authors.lastname: Binz
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001665:Binding Sites; D001905:Botulinum Toxins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; C489614:Sv2a protein, mouse; D001905:Botulinum Toxins; C096326:botulinum toxin type E