title: The HCC-domain of botulinum neurotoxins A and B exhibits a singular ganglioside binding site displaying serotype specific carbohydrate interaction.
abstract: Tetanus and botulinum neurotoxins selectively invade neurons following binding to complex gangliosides. Recent biochemical experiments demonstrate that two ganglioside binding sites within the tetanus neurotoxin HC-fragment, originally identified in crystallographic studies to bind lactose or sialic acid, are required for productive binding to target cells. Here, we determine by mass spectroscopy studies that the HC-fragment of botulinum neurotoxins A and B bind only one molecule of ganglioside GT1b. Mutations made in the presumed ganglioside binding site of botulinum neurotoxin A and B abolished the formation of these HC-fragment/ganglioside complexes, and drastically diminished binding to neuronal membranes and isolated GT1b. Furthermore, correspondingly mutated full-length neurotoxins exhibit significantly reduced neurotoxicity, thus identifying a single ganglioside binding site within the carboxyl-terminal half of the HC-fragment of botulinum neurotoxins A and B. These binding cavities are defined by the conserved peptide motif H...SXWY...G. The roles of tyrosine and histidine in botulinum neurotoxins A and B in ganglioside binding differ from those in the analogous tetanus neurotoxin lactose site. Hence, these findings provide valuable information for the rational design of potent botulinum neurotoxin binding inhibitors.
authors.affiliation: Institute of Biochemistry, Medizinische Hochschule Hannover, D-30623 Hannover, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Rummel
authors.forename: Stefan
authors.initials: S
authors.lastname: Mahrhold
authors.forename: Hans
authors.initials: H
authors.lastname: Bigalke
authors.forename: Thomas
authors.initials: T
authors.lastname: Binz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001905:Botulinum Toxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019274:Botulinum Toxins, Type A / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism; D005732:Gangliosides / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010791:Phrenic Nerve / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D012703:Serotyping; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D005732:Gangliosides; D009498:Neurotoxins; D010446:Peptide Fragments; D011994:Recombinant Proteins; C096323:rimabotulinumtoxinB; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A