Thermostable RNA Ligase Circularization of ssDNA
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Solution Overview
Problem
Current methods for template-independent intramolecular ligation of linear ssDNA molecules using thermostable RNA ligases, such as bacteriophage TS2126 RNA ligase, exhibit variable efficiency depending on sequence and size, leading to inconsistent results in applications like gene expression analysis and genomic DNA amplification.
Innovation Solution
A ligation reaction mixture comprising adenylated thermostable RNA ligase in excess of ssDNA molecules, maintained at pH 6.5-8.0, with optimal manganese concentrations and optional betaine, but without ATP or with ATP at concentrations less than the non-adenylated ligase, facilitates consistent intramolecular ligation across different sequences and sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard thermostable RNA ligase is used for template-independent intramolecular ligation of linear ssDNA, then the ligation can proceed without template, but the ligation efficiency varies significantly depending on sequence and size
Solution Approach 1:
The patent changes the concentration parameter of the ligase by using it in excess relative to the ssDNA substrate (molar ratio >1:1), and optimizes the reaction pH to 6.5-8.0 and manganese concentration to 0.5-5 mM. These parameter adjustments ensure consistent ligation efficiency across different ssDNA sequences and sizes, resolving the reliability issue while maintaining template-independent capability.
2Reliability
If higher ligase concentration is used to improve ligation efficiency, then more consistent results are achieved, but the reaction mixture becomes more complex
Solution Approach 1:
The patent defines specific concentration ranges for ligase (0.01-10 units/μL), pH (6.5-8.0), and manganese (0.5-5 mM) that optimize ligation efficiency without requiring excessive complexity in the reaction mixture. These standardized parameters make the protocol straightforward while achieving reliable results.
3Ease of manufacture
If standard ligation conditions are used, then simple reaction mixture is maintained, but difficult-to-ligate substrates show low yields
Solution Approach 1:
The patent optimizes pH to 6.5-8.0 and manganese concentration to 0.5-5 mM, which significantly improves ligation yield for difficult substrates while maintaining relatively simple reaction conditions. The excess ligase concentration (molar ratio >1:1) further enhances productivity without adding substantial complexity.
Solution Approach 2:
The patent uses manganese ions as a cofactor that enables the ligase to function effectively on difficult substrates, essentially creating an enhanced enzymatic system that copies the successful ligation outcome across various substrate types.
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 significantly enhances the efficiency and consistency of intramolecular ligation, achieving higher yields of circular ssDNA molecules compared to standard methods, particularly for difficult-to-ligate substrates, and allows for broader applicability in nucleic acid analysis and sequencing.
Implementation Method 1
a thermostable RNA ligase, particularly for circularization of ssDNA molecules
Implementation Method 2
template-independent intramolecular ligation of linear ssDNA molecules
Implementation Method 3
a manganese salt at a concentration that is optimal for the thermostable RNA ligase
Implementation Method 4
a buffer that maintains the final pH at between about pH 6.5 and about 8.0
Implementation Method 5
optional betaine, but without ATP or with ATP at concentrations less than the non-adenylated ligase
Data Source
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AI summary
The invention provides ligation reaction mixtures, methods, and kits for improved template-independent intramolecular ligation (circularization) of linear ssDNA, including denatured gDNA fragments or first-strand cDNA made by reverse transcription of RNA, using, for example, a thermostable RNA ligase. The circular ssDNA molecules obtained using the improved ligation reaction mixtures and methods can be used, for example, as templates: for amplification by inverse PCR, rolling circle replication, transcription, or for massively parallel DNA sequencing. Applications include, for example: gene expression analysis by qPCR or using microarrays; analysis of gDNA copy number variation; and detection or quantification of specific nucleic acid sequences for research, screening, medical diagnostics, theranostics, personalized medical treatment or breeding, for purposes such as human or animal medicine, forensics, or agriculture.