Stabilizing Coronavirus Spike Proteins via Disulfide Bridges
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Solution Overview
Problem
Current COVID-19 vaccines face challenges in stabilizing the prefusion state of coronavirus spike proteins, which are unstable and prone to transitioning to the postfusion structure, affecting immune response effectiveness.
Innovation Solution
Engineered polypeptides with specific amino acid substitutions, such as F970C and G999C, form disulfide bridges to stabilize the prefusion S1/S2 spike structure, preventing transition to the postfusion state without rigidifying the central helix or altering its interaction with the receptor binding domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spike protein is used in vaccines, then immune response is stimulated, but the protein transitions from prefusion to postfusion structure reducing stability
Solution Approach 1:
The patent applies parameter changes by introducing specific amino acid substitutions (F970C and G999C) that modify the chemical structure of the spike protein. These substitutions create disulfide bridges that change the structural parameters of the protein, stabilizing it in the prefusion conformation and preventing transition to postfusion state, thereby resolving the stability issue while maintaining immunogenicity
Solution Approach 2:
The patent creates a composite structure by forming disulfide bridges between cysteine residues at positions 970 and 999. This composite covalent linkage integrates two separate protein regions (S1 and S2 subunits) into a stabilized prefusion structure, maintaining the functional components while enhancing overall structural stability and preventing conformational change
2Reliability
If stabilizing mutations are introduced to maintain prefusion state, then protein stability improves, but the central helix becomes rigidified affecting flexibility
Solution Approach 1:
The patent applies local quality by placing disulfide bridges at specific locations (positions 970 and 999) within the spike protein structure. These localized cross-links stabilize the prefusion conformation in specific regions without rigidifying the central helix, allowing the protein to maintain both stability and necessary flexibility for receptor binding and membrane fusion functions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The stabilized prefusion spike proteins maintain stability and flexibility, enhancing immune response by maintaining the original interactions with the receptor binding domain, improving vaccine efficacy without the need for stabilizing mutations.
Implementation Method 1
The modifications include substitutions in the spike proteins which allow for the formation of a disulfide bridge that stabilizes the coronavirus S protein or a portion thereof (e.g., peptide sequence comprising the S1/S2) in the pre-fusion S structure
Data Source
AI summary
Compositions include coronavirus S1/S2 prefusion spike proteins with specifically designed disulfide bond that “staple” together the central helix and a region of the spike known as HR1. By preventing HR1 from detaching from CH, the prefusion spike structure is stabilized without rigidification of the central helix or changes to its interaction with the receptor binding domain. This disulfide-stapled spike is more stable in the prefusion form, allowing for a stable vaccine without the need for the stabilizing mutations that are currently in use.