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Botulinum neurotoxins C, E and F bind gangliosides via a conserved binding site prior to stimulation‐dependent uptake with botulinum neurotoxin F utilising the three isoforms of SV2 as second receptor
Author(s) -
Rummel Andreas,
Häfner Kirstin,
Mahrhold Stefan,
Darashchonak Natallia,
Holt Matthew,
Jahn Reinhard,
Beermann Silke,
Karnath Tino,
Bigalke Hans,
Binz Thomas
Publication year - 2009
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2009.06298.x
Subject(s) - botulinum neurotoxin , neurotoxin , gene isoform , chemistry , stimulation , clostridium botulinum , binding site , receptor , pharmacology , neuroscience , biophysics , biochemistry , toxin , biology , gene
The high toxicity of clostridial neurotoxins primarily results from their specific binding and uptake into neurons. At motor neurons, the seven botulinum neurotoxin serotypes A–G (BoNT/A–G) inhibit acetylcholine release, leading to flaccid paralysis, while tetanus neurotoxin blocks neurotransmitter release in inhibitory neurons, resulting in spastic paralysis. Uptake of BoNT/A, B, E and G requires a dual interaction with gangliosides and the synaptic vesicle (SV) proteins synaptotagmin or SV2, whereas little is known about the entry mechanisms of the remaining serotypes. Here, we demonstrate that BoNT/F as wells depends on the presence of gangliosides, by employing phrenic nerve hemidiaphragm preparations derived from mice expressing GM3, GM2, GM1 and GD1a or only GM3. Subsequent site‐directed mutagenesis based on homology models identified the ganglioside binding site at a conserved location in BoNT/E and F. Using the mice phrenic nerve hemidiaphragm assay as a physiological model system, cross‐competition of full‐length neurotoxin binding by recombinant binding fragments, plus accelerated neurotoxin uptake upon increased electrical stimulation, indicate that BoNT/F employs SV2 as protein receptor, whereas BoNT/C and D utilise different SV receptor structures. The co‐precipitation of SV2A, B and C from Triton‐solubilised SVs by BoNT/F underlines this conclusion.