Fusion Protein System for Post-Translational Modification
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Solution Overview
Problem
Current methods for producing specific forms of post-translationally modified proteins, such as phosphorylated proteins, are inefficient and costly, limiting the study of post-translational modifications like tyrosine phosphorylation, which is relevant in understanding human cancers.
Innovation Solution
A system comprising a fusion protein with a catalytic domain and a targeting domain, linked by a flexible linker, is used to efficiently produce post-translationally modified proteins. This system includes vectors encoding these proteins and host cells for expression, allowing for controlled modification of substrate proteins through enhanced enzyme-substrate interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional in vitro phosphorylation methods are used, then phosphorylated proteins can be produced, but the process is inefficient and costly
Solution Approach 1:
The system uses endogenous cellular machinery to perform post-translational modifications. The fusion protein expression system leverages the cell's own protein synthesis and modification capabilities, eliminating the need for external enzymatic phosphorylation steps and reducing both cost and complexity while maintaining high productivity
Solution Approach 2:
The fusion protein is designed with the catalytic domain and targeting domain pre-assembled in the correct spatial configuration before encountering the substrate. The linker region pre-positions the catalytic domain in proximity to the substrate protein, ensuring that modification occurs immediately upon substrate binding without requiring additional activation steps
2Ease of manufacture
If phosphomimic mutations are used to study phosphorylation effects, then the method is easily implemented, but it fails to recapitulate the size, shape and charge of phosphorylated tyrosine
Solution Approach 1:
The fusion protein acts as an intermediary that transfers the exact chemical structure of the phosphate group from the catalytic domain to the substrate protein. Rather than using phosphomimic mutations that alter the amino acid sequence, the system uses the natural phosphorylation reaction to introduce the authentic phosphate group, ensuring structural accuracy while maintaining ease of implementation through simple fusion protein expression
Solution Approach 2:
The system replaces the mechanical approach of phosphomimic mutation (changing amino acid sequence) with a chemical enzymatic approach (phosphorylation reaction). The catalytic domain performs the chemical transformation in situ, producing the authentic phosphotyrosine residue with correct size, shape, and charge distribution that cannot be achieved through mutation alone
3Manufacturing precision
If chemical ligation is used to produce phosphorylated proteins, then specific phosphorylation can be achieved, but the method is limited by fidelity of phosphopeptide synthesis and only works for tyrosines within 20-45 amino acids of N-terminus
Solution Approach 1:
The fusion protein system is universally applicable to substrate proteins regardless of the position of the target tyrosine residue. The targeting domain can be designed to recognize various substrate sequences, and the linker flexibility allows the catalytic domain to reach tyrosines at any position in the substrate protein, eliminating the 20-45 amino acid limitation while maintaining phosphorylation specificity
Solution Approach 2:
The linker region provides dynamic flexibility that allows the catalytic domain to adapt its position and orientation relative to the substrate protein. This dynamic configuration enables the system to accommodate tyrosine residues at various positions along the substrate polypeptide chain, increasing versatility while the catalytic domain maintains its specificity for phosphorylating the correct residue
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 system enables the production of soluble, folded, and post-translationally modified proteins with increased specificity and efficiency, facilitating the study of modifications like tyrosine phosphorylation, and can produce up to several-fold more modifications compared to traditional methods.
Implementation Method 1
a fusion protein with a catalytic domain and a targeting domain... allowing for controlled modification of substrate proteins through enhanced enzyme-substrate interactions
Data Source
AI summary
The present disclosure provides a system to produce soluble, folded, and post-translationally modified proteins. The system includes a fusion protein comprising a catalytic domain of an enzyme involved in post-translational protein modification and a targeting domain, and a substrate protein comprising a protein of interest and a sequence that interacts with the targeting domain. The present disclosure also provides polynucleotide sequences encoding fusion proteins and substrate proteins, vectors for expressing polynucleotide sequences, vectors comprising the polynucleotide sequences, and isolated cells comprising said vectors.