Engineered Botulinum Neurotoxin Receptor Binding for Syt II Specificity
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Solution Overview
Problem
Current botulinum neurotoxins (BoNTs) face limitations such as the generation of neutralizing antibodies and toxin diffusion, leading to adverse effects and reduced efficacy in therapeutic applications, particularly in muscle spasms, due to their interaction with human Syt II receptors.
Innovation Solution
Modification of the receptor binding domain of BoNT/B with specific substitution mutations, such as E1191C, E1191V, E1191L, S1199W, and others, to enhance binding to human Syt II and reduce binding to human Syt I, thereby improving specificity and efficacy for neuronal targeting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild type BoNT/B is used to treat muscle spasms, then therapeutic effect is achieved, but neutralizing antibodies are generated and toxin diffusion occurs causing adverse effects
Solution Approach 1:
The patent applies local quality by modifying specific amino acid residues (positions 1191, 1199, 1183, 1178) in the receptor binding domain of BoNT/B-HC to change its binding characteristics. This localized modification enhances binding to human Syt II while reducing binding to human Syt I, thereby improving therapeutic efficacy and reducing off-target effects without altering the overall toxin structure
Solution Approach 2:
The patent employs parameter changes by systematically varying amino acid substitutions at key positions in the receptor binding domain. Through testing multiple substitutions (e.g., E1191C, E1191V, E1191L, S1199W) and their combinations, the patent optimizes binding affinity and specificity parameters to achieve enhanced therapeutic effect with reduced toxicity
2Productivity
If high doses of BoNT are administered to achieve therapeutic effect, then muscle spasm relief is improved, but toxin diffusion to other regions increases causing serious adverse effects
Solution Approach 1:
The patent enhances the local binding property of BoNT/B to human Syt II receptors through targeted amino acid substitutions in the receptor binding domain. This improved local affinity allows the toxin to achieve therapeutic effect at lower doses, thereby reducing diffusion to off-target regions and minimizing adverse effects
Solution Approach 2:
The patent creates modified versions of the natural BoNT/B receptor binding domain by copying its structure and introducing specific mutations. These engineered variants (e.g., BoNT/B-HC with E1191C/S1199W) replicate the essential binding function while improving specificity and reducing unwanted interactions
3Reliability
If BoNT/B is used to treat muscle spasms, then therapeutic benefit is achieved, but binding to human Syt I causes off-target effects
Solution Approach 1:
The patent applies local quality by introducing specific amino acid substitutions at positions 1191, 1199, 1183, and 1178 in the receptor binding domain. These localized changes selectively enhance affinity for human Syt II while reducing binding to human Syt I, thereby eliminating off-target effects and improving therapeutic reliability
Data Source
AI summary
Disclosed herein is a botulinum neurotoxin (BoNT) polypeptide with a modified receptor binding domain (HC) having one or more amino acid mutations that modify the binding of the BoNT to the receptor. Specific mutations and combinations of mutations are also disclosed. Isolated modified HC, polypeptides comprising the modified HC, chimeric molecules, pharmaceutical compositions, and methods of making and using the same are also disclosed. Methods of identifying additional such modified receptor binding domains, are further disclosed.