Orthogonal tRNA Expression Vectors for Unnatural Amino Acid Incorporation
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Solution Overview
Problem
The efficiency of existing systems for producing mutant proteins containing unnatural amino acids in vivo is not optimized, particularly in bacterial expression systems, where the suppression efficiency of orthogonal translation systems is poor, limiting the incorporation of chemically diverse unnatural amino acids into proteins.
Innovation Solution
The development of improved expression vector systems that incorporate orthogonal translation technology, featuring specific nucleic acid constructs with promoter and terminator sequences derived from E. coli proline tRNA genes, and orthogonal aminoacyl-tRNA synthetases and suppressor tRNAs, enhancing the incorporation of unnatural amino acids into proteins in E. coli.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If orthogonal translation systems are used to incorporate unnatural amino acids into proteins in E. coli, then the diversity of amino acid R-groups is expanded, but the suppression efficiency and expression yield are poor
Solution Approach 1:
The patent modifies the orthogonal tRNA expression system by changing key parameters: using a modified promoter with higher activity, optimizing the tRNA sequence for better stability and expression, and adjusting the codon usage. These parameter changes collectively improve suppression efficiency while maintaining the ability to incorporate diverse unnatural amino acids
Solution Approach 2:
The patent employs a inducible expression system where the orthogonal tRNA and aminoacyl-tRNA synthetase are expressed under controllable conditions. This dynamic expression allows optimization of suppression efficiency by inducing tRNA production only when needed, thereby improving overall system productivity without compromising amino acid diversity
2Adaptability or versatility
If orthogonal translation systems are used to incorporate unnatural amino acids into proteins in E. coli, then the chemical diversity of proteins is enhanced, but the expression yield is limited
Solution Approach 1:
The patent optimizes expression yield by changing multiple parameters simultaneously: using a high-activity promoter to increase tRNA transcription, optimizing the ribosome binding site for better translation initiation, and adjusting the copy number of the expression vector. These changes collectively enhance expression yield while preserving the chemical diversity capability of the orthogonal system
3Ease of manufacture
If existing expression systems are used for mutant protein production, then the process is simple, but the incorporation efficiency of unnatural amino acids is not optimized
Solution Approach 1:
The patent creates a universal expression system that can incorporate various unnatural amino acids using a single optimized orthogonal tRNA expression vector. This multi-functional system maintains ease of manufacture by using a standardized vector backbone and expression cassette, while improving incorporation efficiency through optimized promoter and tRNA sequence elements that work across different unnatural amino acid applications
Data Source
AI summary
The invention relates to compositions and methods for the in vivo production of polypeptides comprising one or more unnatural amino acids. Specifically, the invention provides plasmid systems for the efficient eubacterial expression of polypeptides comprising one or more unnatural amino acids at genetically-programmed positions.