MeDNA Binding Protein Methylation Quantitation
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Solution Overview
Problem
Current methods for quantitating cytosine methylation in nucleic acids, such as bisulfite treatment, face challenges with low complexity sequences and limited sample size, particularly in sequencing approaches with short read-lengths, and are harsh, making it difficult to analyze small amounts of starting material effectively.
Innovation Solution
A method involving the use of MeDNA binding proteins to form blocking complexes with methylated cytosines, allowing for primer extension, degradation, amplification, and quantitation of methylation differences between target and control nucleic acids, using PCR and specific primers to determine methylation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bisulfite treatment is used to convert non-methylated cytosines to uracil, then methylation detection capability is improved, but sequence complexity decreases making mapping difficult
Solution Approach 1:
The patent applies preliminary action by performing selective degradation of non-methylated nucleic acid sequences before amplification. Using S1 nuclease to digest single-stranded non-methylated regions creates a preparatory step that enriches the sample for methylated sequences, thereby improving detection precision while managing sequence complexity through pre-processing rather than during mapping
Solution Approach 2:
The invention extracts and removes non-methylated sequences from the mixture through selective enzymatic degradation. By taking out the interfering low-complexity sequences before amplification, the patent isolates the methylated sequences of interest, improving both detection precision and effective sequence complexity for subsequent mapping
2Measurement precision
If bisulfite treatment is applied to analyze methylation, then methylation quantitation is achieved, but sample amount requirements increase making small samples difficult to analyze
Solution Approach 1:
The patent segments the analysis process into distinct stages: selective binding of methylated sequences, targeted protection from degradation, selective amplification, and final detection. This segmentation allows optimization at each stage, enabling accurate methylation quantitation while minimizing the required starting material by focusing resources on the relevant methylated sequences rather than processing the entire sample
Solution Approach 2:
The invention introduces intermediary steps including selective binding proteins and protected amplification intermediates. These intermediaries enable the system to enrich and protect methylated sequences from the harsh bisulfite treatment conditions, allowing accurate quantitation while reducing the amount of starting material needed by concentrating on the relevant fraction
3Productivity
If MeDNA binding proteins form blocking complexes with methylated cytosines, then amplification of methylated sequences is enabled, but reaction complexity increases
Solution Approach 1:
The patent merges multiple functions into the MeDNA binding proteins: sequence recognition, protective binding, and amplification facilitation. By combining these functions into a single reagent system, the invention achieves efficient amplification of methylated sequences while managing reaction complexity through functional integration rather than separate sequential steps
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 method enables accurate quantitation of methylation by forming blocking complexes with MeDNA binding proteins, allowing for effective amplification and analysis of methylation levels in target nucleic acids, overcoming the limitations of existing techniques, especially in low complexity and small sample size scenarios.
Implementation Method 1
treating a target nucleic acid with a MeDNA binding protein, wherein the MeDNA binding protein forms a blocking complex with a methylated cytosine in the target nucleic acid
Implementation Method 2
extending a first target specific primer hybridized to the first target specific primer binding site to form a target nucleic acid extension product
Implementation Method 3
degrading the target nucleic acid
Implementation Method 4
amplifying the target nucleic acid extension product
Data Source
AI summary
The present teachings provide DNA methylation quantification methods that avoid bisulfite treatment of DNA. Methylation-specific binding proteins (MeDNA binding proteins) and non-methylation specific binding proteins (non-MeDNA binding proteins) are employed in various embodiments to modulate the accessibility of nucleic acids to primer extension reactions. After selectively removing the target nucleic acids, the extension products can be analyzed and methylation quantitated. In some embodiments, the analysis comprises real-time PCR.