Binding of Botulinum and Tetanus Neurotoxins to Ganglioside GT1b and Derivatives Thereof

Abstract

The ability of fragments derived from botulinum neurotoxin (BTx) serotype A to bind to GT1b-coated plastic wells was investigated and compared with the binding characteristics of the parent approximately 150-kDa protein. Although the approximately 50-kDa light chain of BTxA had a marginal binding capacity, the predominant adherence to GT1b-coated wells was exhibited by the approximately 50-kDa carboxy-terminal half of the approximately 100-kDa heavy chain of BTxA; the amino-terminal half of the heavy chain lacked the ability to bind. Binding to GT1b by BTxA and its fragments was compared with that of tetanus neurotoxin (TTx) and the carboxy-terminal half of its heavy chain. Binding of BTxA and the C-terminal half of the heavy chain was optimal in buffers of low ionic strength (mu less than or equal to 0.04 and 0.06, respectively), whereas the heavy chain bound GT1b best at mu greater than or equal to 0.10. TTx and the approximately 50-kDa C-terminal half of its approximately 100-kDa heavy chain bound GT1b at ionic strengths similar to those of BTxA. Comparison of the binding of BTx serotypes A, B, and E to GT1b (using conditions that were found to be optimal for binding by BTxA) indicated differences in the interaction of the three serotypes with GT1b. Compared with BTxA, adherence to GT1b by serotypes B and E was reduced by approximately 60 and approximately 90%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Botulinum Neurotoxin A Activity Is Dependent upon the Presence of Specific Gangliosides in Neuroblastoma Cells Expressing Synaptotagmin I

“…Specifically, polysialylated gangliosides like GT1b (6) were shown to be involved in BoNT/A neurotoxicity (7,8). Since then, GT1b has been shown to inhibit BoNT/A binding to synaptosomes (9), to quench BoNT/A fluorescence (10), and to be bound by BoNT/A when it was immobilized on either a thin layer chromatogram (11) or on plastic wells (12). The dissociation constant for the adherence of BoNT/A-H C to GT1b-containing liposomes was recently reported to be ϳ10 Ϫ8 M (13).…”

Comparativein vitroandin vivoassessment of toxin neutralization by anti-tetanus toxin monoclonal antibodies

“…As previously mentioned, gangliosides of the 1b series are considered to be the main part of clostridial neurotoxin receptor. Therefore, the GT1b binding assay has been widely utilized [9][10][11]15 as a suitable method to study the inhibitory activity of anti-TeNT antibodies. As shown in Figure 1, six out of seven anti-fragment C antibodies (1F3E3, 1F2C2, 1F1E12, 1F2C8, 2C9B6, and 3B3D9) inhibited TeNT binding to its receptor dose dependently, whereas the anti-LC antibody (1F3B3 and 1F3C3) or anti-light and anti-fragment C antibody (1F4E11) failed to block the binding of the TeNT to GT1b ganglioside.…”

“…8 Considering the gangliosides as the main part of tetanus toxin binding receptor, GT1b binding assay was exploited to evaluate in vitro inhibition of TeNT binding activity. [9][10][11] We have recently assessed the inhibitory potential of four TeNT specific mAbs (1F3E3, 1F2C2, 1F3B3, and 1F4E11) using the in vitro GT1b binding assay. 12 However, there is no detailed information about the validity and relevance of this method to the results obtained from in vivo experiments.…”

Why do microbes have toxins?

“…Shiga toxin also inhibits protein synthesis, but through inactivation of host cell ribosomes by specific depurination of the 28S rRNA species (Li 1992). The neurotoxins botulinum and tetanus toxins have similar receptors and modes of action (Schengrund et al 1991) in that they are both zinc endopeptidases that cleave a class of proteins (synaptobrevins) whose role is to control the release of neurotransmitters at nerve-nerve or nerve-muscle junctions. However, the outcomes are diametrically opposed (Li 1992) ; botulinum toxin causes flaccid paralysis by inhibiting nerve stimulation, while tetanus toxin causes spastic paralysis by inhibiting the activity of inhibitory compounds.…”