Aptamer Riboswitch Control of U1-Mediated Polyadenylation
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Solution Overview
Problem
Current methods for regulating gene expression do not effectively utilize U1 snRNP-mediated polyadenylation suppression to modulate mRNA stability and expression in response to specific ligands.
Innovation Solution
A polynucleotide cassette with a riboswitch containing an effector region and an aptamer is used to sequester U1 snRNP binding sites, allowing modulation of gene expression by forming a stem upon ligand binding, thereby preventing U1 snRNP interaction and promoting polyadenylation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a U1 binding site is placed in the 3' UTR to suppress polyadenylation, then gene expression is reduced, but the system lacks responsiveness to specific ligands for precise regulation
Solution Approach 1:
The riboswitch structure dynamically changes conformation in response to ligand binding. When the ligand binds to the aptamer domain, it induces a structural change that alters the accessibility of the U1 binding site, transitioning between suppressed and active gene expression states. This dynamic structural transition enables ligand-responsive control while maintaining reliable suppression in the absence of ligand.
Solution Approach 2:
The riboswitch acts as an intermediary between the ligand and the U1 binding site. The aptamer domain specifically binds the ligand, and this binding event is transmitted through the riboswitch structure to modulate the accessibility of the U1 binding site. This intermediary mechanism enables precise ligand-responsive regulation without direct interaction between the ligand and the U1 binding site.
2Reliability
If multiple U1 binding sites are used to enhance suppression, then gene expression control is improved, but the complexity of the regulatory system increases
Solution Approach 1:
The invention merges multiple functional elements into a single integrated riboswitch structure. The aptamer domain, effector region, and U1 binding sites are combined into one cohesive regulatory unit. This merging approach enhances polyadenylation suppression through cooperative binding while avoiding the complexity of separate regulatory components, as the entire structure responds to ligand binding in a coordinated manner.
3Reliability
If the U1 binding site is made more accessible to enhance suppression, then polyadenylation inhibition is improved, but the system loses the ability to dynamically regulate expression in response to ligands
Solution Approach 1:
The riboswitch structure is designed with dynamic accessibility of the U1 binding site. In the absence of ligand, the U1 binding site is exposed and accessible for strong suppression. Upon ligand binding, the structural transition sequesters or exposes the U1 binding site as needed. This dynamic accessibility control maintains reliable inhibition when required while enabling precise temporal regulation in response to ligand presence.
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 precise control over gene expression by increasing or decreasing mRNA stability based on the presence or absence of a ligand, enhancing regulatory flexibility and efficiency.
Implementation Method 1
the sensor region comprises an aptamer. When the aptamer ligand is present, it binds the aptamer causing the effector region to form a stem
Implementation Method 2
the effector region contains a U1 snRNP binding site and sequence complimentary to the U1 snRNP binding site such that the two sequences are capable of forming a stem that sequesters the U1 snRNP binding site
Data Source
AI summary
The invention provides polynucleotide constructs for the regulation of gene expression by aptamer-based modulation of U1 snRNP-mediated suppression of polyadenylation and methods of using the constructs to regulate gene expression in response to the presence or absence of a ligand that binds the aptamer. The polynucleotide construct contains a U1 binding site in the context of a riboswitch comprising an effector region and an aptamer such that when the aptamer binds a ligand, target gene expression occurs.