Structural highlights
Function
[BXA1_CLOBO] Inhibits acetylcholine release. The botulinum toxin binds with high affinity to peripheral neuronal presynaptic membrane to the secretory vesicle protein SV2. It binds directly to the largest luminal loop of SV2A, SV2B and SV2C. It is then internalized by receptor-mediated endocytosis. The C-terminus of the heavy chain (H) is responsible for the adherence of the toxin to the cell surface while the N-terminus mediates transport of the light chain from the endocytic vesicle to the cytosol. After translocation, the light chain (L) hydrolyzes the 197-Gln-|-Arg-198 bond in SNAP-25, thereby blocking neurotransmitter release. Inhibition of acetylcholine release results in flaccid paralysis, with frequent heart or respiratory failure.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Broadening antibody specificity without compromising affinity should facilitate detection and neutralization of toxin and viral subtypes. We used yeast display and a co-selection strategy to increase cross-reactivity of a single chain (sc) Fv antibody to botulinum neurotoxin type A (BoNT/A). Starting with a scFv that binds the BoNT/A1 subtype with high affinity (136 pM) and the BoNT/A2 subtype with low affinity (109 nM), we increased its affinity for BoNT/A2 1,250-fold, to 87 pM, while maintaining high-affinity binding to BoNT/A1 (115 pM). To find the molecular basis for improved cross-reactivity, we determined the X-ray co-crystal structures of wild-type and cross-reactive antibodies complexed to BoNT/A1 at resolutions up to 2.6 A, and measured the thermodynamic contribution of BoNT/A1 and A2 amino acids to wild-type and cross-reactive antibody binding. The results show how an antibody can be engineered to bind two different antigens despite structural differences in the antigen-antibody interface and may provide a general strategy for tuning antibody specificity and cross-reactivity.
Molecular evolution of antibody cross-reactivity for two subtypes of type A botulinum neurotoxin.,Garcia-Rodriguez C, Levy R, Arndt JW, Forsyth CM, Razai A, Lou J, Geren I, Stevens RC, Marks JD Nat Biotechnol. 2007 Jan;25(1):107-16. Epub 2006 Dec 17. PMID:17173035[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Garcia-Rodriguez C, Levy R, Arndt JW, Forsyth CM, Razai A, Lou J, Geren I, Stevens RC, Marks JD. Molecular evolution of antibody cross-reactivity for two subtypes of type A botulinum neurotoxin. Nat Biotechnol. 2007 Jan;25(1):107-16. Epub 2006 Dec 17. PMID:17173035 doi:10.1038/nbt1269
