Chimeric T1R Receptors for Sweet Taste Modulator Screening
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Solution Overview
Problem
Current screening methods for sweetness modifiers or enhancers face challenges due to the effects of sweeteners on osmolarity and viscosity, and the wildtype T1R2/T1R3 receptor's binding domains interfere with specific ligand binding, making it difficult to identify modulators that bind to transmembrane or cysteine-rich domains without competing with carbohydrates.
Innovation Solution
The use of CSR::T1R chimeric proteins, which are homologous to specific T1R2 and T1R3 polypeptides, allows for the identification of sweetener modulators by binding at sites distinct from the Venus flytrap domains, using calcium as a ligand to avoid adverse sweetener effects and enabling the detection of compounds that modulate sweet taste signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard screening methods using wildtype T1R2/T1R3 receptor are used, then sweetness modifiers can be identified, but artifacts occur due to changes in osmolarity and viscosity caused by sweeteners
Solution Approach 1:
The invention extracts and removes the Venus flytrap domains from the T1R2 and T1R3 receptors to create chimeric receptors. This extraction eliminates the carbohydrate-binding capability that causes artifacts, while preserving the transmembrane domain functionality for detecting sweetness modulators. The removed VFT domains are the source of the harmful artifact-generating interactions with sugars.
Solution Approach 2:
The invention introduces calcium as an intermediary ligand that binds to the chimeric receptor in place of traditional sweeteners. Calcium serves as a mediator that activates the receptor without causing the osmolarity and viscosity artifacts associated with sugar-based sweeteners, enabling reliable screening of sweetness modulators.
2Adaptability or versatility
If wildtype T1R2/T1R3 receptor is used for screening, then general sweetness modifiers can be detected, but specific ligands binding to transmembrane or cysteine-rich domains cannot be identified due to VFT domain interference
Solution Approach 1:
The Venus flytrap domains are extracted and removed from the receptor structure, eliminating their interference with transmembrane domain ligand binding. This allows specific ligands that target the TMD or cysteine-rich domains to be detected without competitive inhibition from carbohydrate-binding sites.
Solution Approach 2:
The invention creates chimeric receptors with localized functional domains: the extracellular domain is replaced with calcium-binding capability while the transmembrane and cysteine-rich domains retain their original ligand-binding properties. This local modification enables specific detection of TMD-binding ligands while maintaining overall receptor functionality.
3Measurement precision
If sweeteners are used in screening samples, then sweetness enhancer effects can be measured, but viscosity and osmolarity changes cause measurement artifacts
Solution Approach 1:
Calcium is introduced as an intermediary substance that replaces traditional sweeteners in the screening assay. As a small ion, calcium does not significantly alter sample viscosity or osmolarity, eliminating the physical artifacts that complicate measurements while still enabling detection of sweetness enhancer effects through receptor activation.
Data Source
AI summary
Novel chimeric proteins functional to screen for sweet taste modulators, the corresponding nucleic acid sequences, expression vectors, transfected host cells, and screening methods for modulators and enhancers of the sweet taste response employing the aforementioned are provided.