Water-Soluble GPCR via Hydrophobic Residue Replacement
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Solution Overview
Problem
Current methods are inadequate for producing milligrams of stable, soluble olfactory receptors necessary for detailed structural studies, due to their water-insolubility and the lack of inexpensive large-scale production techniques, hindering the understanding of their structure and function.
Innovation Solution
A method involving the replacement of hydrophobic residues in the 7-transmembrane α-helical domain of G-protein coupled receptors with hydrophilic residues like glutamine, threonine, and tyrosine to create a water-soluble variant, maintaining ligand-binding activity and facilitating structural analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrophobic residues are replaced with hydrophilic residues to increase water solubility, then solubility is improved, but structural stability may deteriorate
Solution Approach 1:
The patent applies local quality by selectively replacing hydrophobic residues with hydrophilic residues only at specific surface-exposed positions (b, c, and f) of the transmembrane helices, while preserving hydrophobic residues at core positions (a, d, e, and g). This localized modification approach maintains the hydrophobic core necessary for structural stability while introducing hydrophilicity at the surface to improve water solubility.
2Productivity
If milligrams quantities of soluble receptors are produced for structural studies, then research capability is improved, but production difficulty remains high
Solution Approach 1:
The patent applies parameter changes by systematically modifying the amino acid composition parameters of the receptor protein - specifically replacing hydrophobic residues (Leucine, Isoleucine, Valine, Phenylalanine) with hydrophilic residues (Glutamine, Threonine, Tyrosine) at defined positions. This parameter modification transforms the protein's solubility characteristics, enabling large-scale production in aqueous environments and facilitating structural studies.
3Reliability
If ligand-binding activity is maintained in water-soluble variants, then therapeutic potential is improved, but solubility is reduced
Solution Approach 1:
The patent applies segmentation by dividing the transmembrane helix into distinct positional segments (a, b, c, d, e, f, g) and applying different residue replacement strategies to each segment. Positions b, c, and f are modified with hydrophilic residues to enhance solubility, while positions a, d, e, and g are preserved to maintain ligand-binding activity and structural integrity.
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
This approach enables the production of water-soluble G-protein coupled receptors, allowing for structural studies and potential therapeutic applications in diseases such as cancer and cardiovascular diseases, while maintaining biological activity and solubility.
Implementation Method 1
replacing each of the 7-transmembrane α-helical hydrophobic residues Leucine (L), isoleucine (I), valine (V), and phenylalanine (F) in hydrophilic surface α-helical positions b, c, and f but not positions a, d, e, and g of the GPCR, with glutamine (Q), threonine (T), threonine (T), and tyrosine (Y), respectively
Data Source
Figure 1
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Figure 3A~3C
AI summary
The present invention is directed to water-soluble membrane proteins, methods for the preparation thereof and methods of use thereof.