NSAA Protein Production Using N-End Rule Quality Selection
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Solution Overview
Problem
Existing methods for incorporating non-standard amino acids (NSAAs) into proteins suffer from inefficiencies and inaccuracies due to the promiscuity of engineered amino-acyl tRNA synthetases and transfer RNAs, leading to the misincorporation of standard amino acids and non-target NSAAs, which can result in impurities and reduced yields.
Innovation Solution
A method utilizing an engineered amino-acyl tRNA synthetase and transfer RNA pair to introduce NSAAs, combined with a removable protecting group and a protease system based on the N-end rule pathway, allows for selective degradation of proteins containing undesired amino acids, ensuring accurate incorporation of desired NSAAs by degrading proteins with standard or undesired NSAAs at the target location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If engineered amino-acyl tRNA synthetases and transfer RNAs are used to incorporate nonstandard amino acids into proteins, then the diversity of amino acid types is improved, but the manufacturing precision deteriorates due to promiscuity and nonspecificity leading to misincorporation of standard amino acids and non-target nonstandard amino acids
Solution Approach 1:
The patent introduces an N-terminal tag as an intermediary element that mediates the selection process. The tag serves as a recognition site for proteases, enabling indirect selection of correctly incorporated nonstandard amino acids by marking incorrectly incorporated proteins for degradation. This intermediary mechanism resolves the contradiction by allowing diverse amino acid incorporation while maintaining precision through protease-mediated quality control.
Solution Approach 2:
The system implements feedback control through protease-mediated degradation. The N-terminal tag provides real-time feedback on incorporation accuracy: when a standard or non-target nonstandard amino acid is incorporated, the tag remains recognizable by proteases, triggering degradation. This feedback loop continuously refines the incorporation process, ensuring high manufacturing precision while maintaining versatility in amino acid selection.
2Manufacturing precision
If in vitro protein purification followed by low-throughput mass spectrometry is used to determine fidelity of nonstandard amino acid incorporation, then the manufacturing precision is improved, but the productivity deteriorates due to laborious analysis slowing down the process
Solution Approach 1:
The patent replaces the mechanical/chemical analysis system (mass spectrometry) with a biological recognition system (protease-tag interaction). Instead of using complex instrumentation to detect incorporation fidelity, the system uses proteases that naturally recognize specific N-terminal amino acids. This substitution dramatically increases productivity while maintaining precision, as the biological system provides real-time, high-throughput selection without laborious analytical steps.
Solution Approach 2:
The system enables self-service quality control where the protein synthesis system itself performs the fidelity check. The N-terminal tag automatically marks incorrectly incorporated proteins for degradation by proteases, eliminating the need for external quality control procedures. This self-service mechanism maintains high manufacturing precision while achieving high productivity through automated, real-time selection during the synthesis process.
3Device complexity
If the incorporation of standard amino acids instead of nonstandard amino acids occurs, then the device complexity is reduced, but the loss of substance increases due to formation of impurities and heterogeneous mixtures lowering yields
Solution Approach 1:
The patent converts the harmful effect of promiscuous amino acid incorporation into a beneficial selection mechanism. The N-terminal tag, which could be seen as an added complexity, actually enables protease-mediated degradation of incorrectly incorporated proteins. This transforms the problem of misincorporation into a solution: the tag marks impurities for removal, converting the harm of heterogeneous mixture formation into the benefit of automated purification and yield enhancement.
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 enhances the production yield of proteins with desired NSAAs by selectively enriching proteins with the correct amino acid at the target location, reducing impurities and improving the accuracy and efficiency of NSAA incorporation.
Implementation Method 1
a protease system based on the N-end rule pathway, allows for selective degradation of proteins containing undesired amino acids
Data Source
AI summary
The disclosure provides methods of making a protein having a desired non-standard amino acid incorporated at its N-terminus in a cell and methods of screening for an amino acyl tRNA synthetase variant that preferentially selects a non-standard amino acid against its standard amino acid counterpart or undesired non-standard amino acids for incorporation into a protein in a cell.