Chimeric Umami Receptor for Transmembrane Domain Modulator Screening
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Solution Overview
Problem
Current methods for screening umami modulators, such as those using the wildtype T1R1/T1R3 receptor, are limited as they cannot distinguish between agents binding to the venus flytrap domain and those binding to the transmembrane domains, leading to the identification of ineffective umami enhancers for food applications.
Innovation Solution
The use of CSR::T1R chimeric proteins, which allow for the identification of umami receptor modulators that bind outside the MSG binding site by employing calcium as a ligand for receptor activation, enabling the identification of specific modulators that do not compete with glutamate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wildtype T1R1/T1R3 receptor is used for screening umami modulators, then the screening can be performed with a complete receptor structure, but the screen cannot distinguish between agents binding to the venus flytrap domain and those binding to the transmembrane domains, leading to identification of ineffective umami enhancers
Solution Approach 1:
The invention divides the umami receptor into separate functional domains by creating chimeric receptors that contain only the transmembrane domains (TMDs) of T1R1 and T1R3, excluding the venus flytrap domains (VFTs). This segmentation allows independent screening of ligands that bind specifically to TMDs versus VFTs, resolving the inability to distinguish binding sites in the wildtype receptor.
Solution Approach 2:
The invention extracts and removes the VFT domains from the receptor structure, creating a minimal chimera consisting only of the TMDs. This extraction enables specific identification of ligands that bind to TMDs without interference from VFT-binding ligands, directly solving the problem of distinguishing binding sites.
2Reliability
If glutamate/MSG is used as the ligand for receptor activation in screening, then the umami taste pathway can be activated, but agents that compete for binding at the VFT site cannot be distinguished from effective umami enhancers
Solution Approach 1:
The invention introduces a chimeric receptor as an intermediary system that uses calcium as a surrogate ligand to activate the TMDs. This intermediary approach allows screening for compounds that enhance calcium-induced activation, specifically identifying agents that bind to TMDs rather than competing at the VFT glutamate binding site.
Solution Approach 2:
The invention changes the ligand parameter from glutamate/MSG (which binds to VFT) to calcium (which binds to TMDs). This parameter change fundamentally alters the binding site being probed, enabling identification of enhancers that act at the TMD level without VFT competition.
3Adaptability or versatility
If a comprehensive receptor structure is used to ensure all binding sites are covered, then the screening can detect all types of modulators, but it cannot identify modulators that specifically bind to transmembrane domains outside the MSG binding site
Solution Approach 1:
The invention segments the receptor screening approach into distinct domain-specific assays: one using the full wildtype receptor to detect all modulators, and another using the TMD-only chimera to specifically detect TMD-binding modulators. This segmentation provides both versatility and precision simultaneously.
Solution Approach 2:
The invention adds a new dimension to receptor screening by creating a truncated version that lacks the N-terminal VFT domains. This dimensional change (removing domains) creates a novel screening tool that probes a different spatial region of the receptor, enabling complementary information gathering.
Data Source
AI summary
Novel chimeric proteins functional to screen for umami taste modulators, the corresponding nucleic acid sequences, expression vectors, transfected host cells, and screening methods for modulators and enhancers of the umami taste response employing the aforementioned are provided.