Artificial Ribozyme T-Box Flexizyme tRNA Charging
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Solution Overview
Problem
Current methods for introducing unnatural amino acids into eukaryotic cells are inefficient and often result in crosstalk with endogenous tRNA and synthetase sets, limiting the variety of amino acids that can be incorporated into proteins.
Innovation Solution
Development of artificial ribozymes comprising a T-box element and a flexizyme, which recognize and bind tRNA substrates with specificity, allowing for the efficient charging of tRNA with a wide variety of unnatural amino acids through a CCA-tail at the 3′-terminus, enabling their incorporation into proteins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional aminoacyl tRNA synthetases are used to charge tRNA with unnatural amino acids, then site-specific incorporation of uAAs is achieved, but crosstalk with endogenous tRNA and synthetase sets occurs and limits the variety of amino acids that can be incorporated
Solution Approach 1:
The invention divides the aminoacyl tRNA synthetase function into two separate RNA components: a T-box element that provides tRNA recognition specificity and a flexizyme catalytic domain that performs amino acid charging. This segmentation allows each component to be optimized independently—the T-box for specific tRNA binding without endogenous crosstalk, and the flexizyme for accommodating diverse unnatural amino acids—thereby resolving the contradiction between versatility and reliability
Solution Approach 2:
The ribozyme acts as an intermediary system between the tRNA and unnatural amino acids, replacing the conventional protein-based synthetase. The T-box element serves as a mediator that specifically recognizes and binds the target tRNA through base pairing, while the flexizyme mediates the catalytic charging reaction. This intermediary RNA-based system avoids crosstalk with endogenous protein synthetases while maintaining specific tRNA recognition and enabling incorporation of a wide variety of unnatural amino acids
2Reliability
If orthogonal tRNA and synthetase sets are engineered for uAA incorporation, then independence from endogenous machinery is achieved, but the system complexity increases and functional compatibility is limited
Solution Approach 1:
The invention merges the tRNA recognition function ( traditionally performed by the synthetase) with the catalytic charging function into a single ribozyme molecule. The T-box element and flexizyme are combined in one RNA structure that can specifically recognize target tRNA and catalyze amino acid charging autonomously. This merging simplifies the system by eliminating the need for separate orthogonal synthetase proteins while maintaining independence from endogenous machinery and enabling functional compatibility with the translation apparatus
Solution Approach 2:
The flexizyme catalytic domain provides universal amino acid charging capability that can accommodate a wide variety of unnatural amino acids without requiring reengineering of the recognition system. The T-box element maintains specific tRNA recognition while the flexizyme handles diverse substrates, creating a universal charging mechanism that works with multiple uAAs. This multi-functionality reduces system complexity compared to engineering separate orthogonal pairs for each amino acid
3Adaptability or versatility
If site-specific incorporation of unnatural amino acids is achieved through conventional methods, then protein functionality is improved, but the chemical diversity of proteins is limited
Solution Approach 1:
The invention changes the chemical parameters of the amino acid substrate by utilizing the flexizyme's ability to accommodate diverse unnatural amino acids with various chemical groups. The ribozyme system maintains efficient catalysis while accepting amino acids with modified side chains, enabling incorporation of chemically diverse uAAs including those with aromatic, aliphatic, charged, and bulky groups. This parameter flexibility increases chemical diversity without sacrificing incorporation efficiency
Solution Approach 2:
The ribozyme system provides dynamic adaptability in substrate recognition through the flexizyme's flexible active site that can adjust to accommodate different unnatural amino acid structures. Unlike rigid conventional synthetases, the flexizyme can dynamically adjust its binding mode to accept various uAAs, thereby enhancing chemical diversity while maintaining high productivity through efficient catalytic charging
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 artificial ribozymes provide a robust mechanism for selectively charging tRNA with unnatural amino acids in eukaryotic cells, enhancing the chemical diversity of proteins and avoiding crosstalk with endogenous machinery, thus improving protein engineering capabilities.
Implementation Method 1
ribosome molecules read down the length of mRNA codons (each a sequence of three-nucleotides) and translate the genetic information contained therein to a specific sequence of amino acids by facilitating complementary base pairing to the complementary transfer RNA (tRNA) anticodons
Implementation Method 2
each of the tRNA molecules that bind the mRNA is 'charged,' meaning that it is carrying a specific amino acid via a covalent bond
Data Source
AI summary
Ribozymes exhibiting tRNA synthetase activity and substrate specificity, as well as methods for engineering and producing the same, are disclosed. The ribozymes of the present disclosure comprise a T-box RNA module fused with a flexizyme module. The flexizyme module provides high promiscuity with respect to amino acid substrates and the T-box module provides tRNA substrate specificity. Systems are also described for aminoacylation of suppressor tRNAs with unnatural amino acids (uAAs), such systems comprising the ribozyme previously mentioned, suppressor tRNA, and the desired uAAs. Methods for incorporating a uAA into a growing polypeptide chain using the ribozyme hereof are also provided.