Covalently Tethered Primer for High-Resolution DNA Modification Mapping
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Solution Overview
Problem
Current methods for analyzing DNA modifications, such as methylation and hydroxymethylation, face limitations including low resolution and labor-intensive procedures, which hinder precise mapping of modification sites in nucleic acid sequences.
Innovation Solution
A method involving a nucleic acid polymerase reaction where a primer is covalently tethered to a target site in the template nucleic acid sequence, allowing for primer extension without extensive base pairing, enabling high-resolution mapping of modification sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bisulfite conversion-based techniques are used for DNA modification analysis, then mapping resolution is improved to single nucleotide level, but the procedure becomes tedious, labor-intensive and prone to experimental artefacts
Solution Approach 1:
The invention extracts and eliminates the problematic bisulfite conversion step from the workflow. Instead of converting all cytosines to uracils through bisulfite treatment, the method directly sequences DNA after selective labeling of modified bases, removing the source of experimental artifacts and labor-intensive processing while maintaining single-nucleotide resolution through targeted enrichment approaches
Solution Approach 2:
The invention performs preliminary selective labeling of modified bases (such as 5mC and 5hmC) before sequencing. By using enzymes like TET2 for hydroxymethylation or methyltransferases for methylation detection, the method pre-identifies and tags modified sites, allowing direct sequencing without bisulfite conversion and enabling straightforward mapping of modification locations at single-nucleotide resolution
2Ease of operation
If affinity-based techniques like MeDIP or MethylCap are used, then the procedure is simplified, but mapping resolution decreases due to minimal DNA fragment size requirements
Solution Approach 1:
The invention introduces enzymatic intermediaries (such as TET2 enzyme for hydroxymethylation detection or specific methyltransferases) that act as mediators between the DNA and sequencing process. These enzymes selectively recognize and process modified bases, enabling precise mapping of modification sites at single-nucleotide level while maintaining procedural simplicity through direct enzymatic conversion or labeling followed by standard sequencing protocols
Solution Approach 2:
The invention replaces the mechanical/physical approach of affinity binding (using antibodies or methyl-binding proteins to pull down DNA fragments) with an enzymatic chemical approach. By using enzymes that specifically catalyze reactions at modified base sites, the method achieves higher precision mapping without relying on fragment size constraints inherent in affinity-based enrichment methods
3Reliability
If covalent tagging methods are used for modification site identification, then specific labeling is achieved, but the resolution is limited by minimal DNA fragment size for PCR amplification
Solution Approach 1:
The invention extracts and removes the PCR amplification step from the workflow. By using direct sequencing methods on enzymatically processed DNA without requiring PCR amplification of minimal fragments, the method eliminates the resolution limitation imposed by PCR constraints while maintaining the specificity of covalent tagging through direct enzymatic labeling of modified bases
Solution Approach 2:
The invention uses enzymatic copying mechanisms where enzymes like TET2 or methyltransferases create specific chemical modifications or labels at modified base sites that can be directly detected by sequencing. This enzymatic copying approach preserves single-nucleotide resolution information without requiring fragment amplification, allowing precise mapping of modification sites through the copied chemical signatures rather than through PCR-amplified fragments
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 allows for precise determination of modification sites and their context, providing a more efficient and accurate method for analyzing DNA modifications compared to existing techniques.
Implementation Method 1
a linking unit attached to a primer, wherein the linking unit is attached to a target site in the template nucleic acid sequence with a covalent linkage
Implementation Method 2
contacting the template nucleic acid sequence with a nucleic acid polymerase under conditions which allow the nucleic acid polymerase to produce the nucleic acid molecule from the primer
Data Source
AI summary
A method for producing a nucleic acid molecule from a template nucleic acid sequence and a linking unit attached to a primer, which method comprises a step of contacting the template nucleic acid sequence with a nucleic acid polymerase under conditions which allow the nucleic acid polymerase to produce the nucleic acid molecule from the primer based on the template nucleic acid sequence, wherein the linking unit is attached to a target site in the template nucleic acid sequence with a covalent linkage.