Ribosome Display Complex Modification via Cysteine Residue Targeting
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Solution Overview
Problem
The ribosome display method is hindered by the instability of the ribosome complex when attempting to bind functional molecules due to the reactivity of cysteine, lysine, histidine, and tryptophan residues in ribosomal proteins, leading to complications in modifying target cysteine residues without impairing the ribosome's function.
Innovation Solution
A method is developed to modify cysteine, lysine, histidine, or tryptophan residues in the displayed polypeptide with a functional molecule using a simple step, maintaining the adhesive function between the polypeptide and mRNA, by selecting appropriate reactive amino acid residues and timing the modification process to avoid interfering with the ribosome's function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a functional molecule is bound to a polypeptide in ribosome display method, then the stability and function of the polypeptide can be improved, but the ribosome complex becomes unstable and the ribosome function is impaired due to reactive amino acid residues in ribosomal proteins
Solution Approach 1:
The patent applies preliminary action by performing the chemical modification of the displayed polypeptide while it is still bound to the ribosome-mRNA complex, before the complex dissociates. This timing allows the modification to occur under controlled conditions where the polypeptide is accessible, and the modified polypeptide-ribosome complex can then be purified and the polypeptide released in a stable form, avoiding the instability issues that would occur if modification attempted after complex dissociation
Solution Approach 2:
The ribosome-mRNA-polypeptide complex itself serves as an intermediary system that enables the chemical modification to proceed selectively on the displayed polypeptide. The complex structure allows modifying reagents to access specific amino acid residues on the polypeptide while the ribosome provides a protective framework that prevents unwanted side reactions, thus mediating between the need for chemical modification and the requirement for complex stability
2Manufacturing precision
If chemical modification is performed on the displayed polypeptide, then the affinity and selectivity of the polypeptide can be improved, but the procedure becomes complicated and the ribosome function is impaired
Solution Approach 1:
The patent merges the chemical modification step with the ribosome display process itself, rather than treating them as separate sequential steps. The modification is performed in situ on the ribosome-displayed polypeptide, combining the advantages of ribosome display (maintaining genotype-phenotype linkage) with chemical modification (improving stability and affinity), thereby simplifying the overall procedure while achieving both goals simultaneously
3Reliability
If cysteine, lysine, histidine, or tryptophan residues in the displayed polypeptide are modified with a functional molecule, then the function and stability of the polypeptide are improved, but the reactive residues in ribosomal proteins may interfere with the modification process
Solution Approach 1:
The patent applies local quality by exploiting the spatial distinction between the displayed polypeptide and the ribosomal proteins. The modifying reagents are designed to access and react with specific amino acid residues on the displayed polypeptide that are exposed in the ribosome complex, while the reactive residues on the ribosomal proteins are either buried or sterically protected, thus achieving selective modification of the target polypeptide without interference from ribosomal components
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 allows for the easy and simple chemical modification of the displayed polypeptide in the ribosome complex without inhibiting the ribosome's function, enabling the production of a stable and functional ribosome display complex with improved affinity and selectivity.
Implementation Method 1
an mRNA molecule is translated by a cell-free peptide synthesis system using a ribosome to obtain a ribosome complex which contains an unmodified polypeptide chain, the mRNA molecule and the ribosome
Implementation Method 2
cysteine, lysine, histidine, or tryptophan residues in the polypeptide chain are reacted with a modifying reagent to modify the residues with a functional molecule
Data Source
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AI summary
The objective of the present invention is to provide a ribosome complex which can be produced without a cumbersome reaction procedure and of which displayed polypeptide is modified without impairing a function of the ribosome, particularly function to produce a polypeptide library, and a method for producing the ribosome complex. The method for producing a ribosome display complex according to the present invention is characterized in comprising the steps of translating the mRNA molecule in a cell-free peptide synthesis system utilizing the ribosome to obtain a ribosome complex comprising an unmodified polypeptide chain, the mRNA molecule and the ribosome, and modifying the unmodified polypeptide chain by reacting the side chain reactive functional group in the unmodified polypeptide chain with a modifying reagent.