Enzymatic Deamination-Resistant DNA Adapters for Epigenetic Sequencing
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Solution Overview
Problem
Current methods for cytosine methylation profiling, particularly in the context of 5mC and 5hmC, are inefficient and inaccurate due to the destructive nature of sodium bisulfite treatment and the inability to distinguish between these modifications during sequencing.
Innovation Solution
The use of modified cytosine analogs, such as 5-propynyl-dC, 5-pyrrolo-dC, and 5hmC, which are resistant to enzymatic deamination, in combination with specific binding pairs and solid-phase immobilization, allows for the development of methods that can accurately profile cytosine modifications by resisting deamination and enabling simultaneous genetic and epigenetic sequencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sodium bisulfite treatment is used for cytosine methylation profiling, then unmodified cytosines can be converted to uracil for detection, but the treatment is destructive and cannot distinguish between 5mC and 5hmC modifications
Solution Approach 1:
The patent introduces deaminase enzymes as intermediary agents that selectively deaminate unmodified cytosines to uracil while leaving 5mC and 5hmC modifications intact. This enzymatic mediation replaces the destructive chemical bisulfite treatment, enabling accurate detection of cytosine modifications without destroying the DNA sample or losing the ability to distinguish between different modification states
Solution Approach 2:
The patent changes the chemical parameter of cytosine detection by using enzymatic deamination instead of chemical deamination. This parameter change allows the DNA to maintain its structural integrity while still enabling the conversion of unmodified cytosines to detectable uracil, thereby improving both measurement precision and sample reliability
2Loss of information
If conventional sequencing methods are used, then genetic information can be obtained, but epigenetic modifications such as 5mC and 5hmC cannot be simultaneously determined
Solution Approach 1:
The patent creates a universal sequencing method that simultaneously determines both genetic information and epigenetic modifications (5mC, 5hmC) in a single sequencing run. By using deaminase treatment followed by standard sequencing procedures, the method achieves multi-functionality, extracting multiple types of information from the same DNA sample without requiring separate specialized assays
Solution Approach 2:
The patent employs a self-service approach where the DNA sample itself provides the basis for both genetic and epigenetic analysis. The deaminase treatment selectively modifies only unmodified cytosines, creating a self-differentiating system where the presence or absence of modifications is automatically revealed during sequencing, eliminating the need for complex external labeling or separate detection systems
3Measurement precision
If deaminase treatment is applied to DNA, then unmodified cytosines are converted to uracil, but modified cytosines (5mC, 5hmC) remain resistant and indistinguishable
Solution Approach 1:
The patent converts the resistance of modified cytosines to deamination into a beneficial feature. Instead of viewing this resistance as a problem that prevents detection, the method exploits it to create a clear distinction: unmodified cytosines are converted to detectable uracil, while modified cytosines remain unchanged. This conversion of resistance into a detection advantage enables simultaneous identification of both modified and unmodified states
Solution Approach 2:
The patent inverts the traditional detection approach by not trying to directly detect modified cytosines, but rather by detecting the absence of modification through deamination. By converting unmodified cytosines to uracil and sequencing, the method indirectly identifies modified cytosines as those positions that retain cytosine, thereby inverting the detection logic to achieve comprehensive modification profiling
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 enhances the efficiency and accuracy of cytosine methylation profiling, allowing for the resolution of multiple DNA modification states in a single DNA molecule and the simultaneous determination of genetic and epigenetic information, with applications in personalized medicine and forensic science.
Implementation Method 1
modified cytosine base including without limitation, 5-propynyl-dC (5pyC), 5-pyrrolo-dC (5pyrC), 5hmC along with modified variants thereof, cytosine 5-methylenesulfonate (CMS), glucosylated 5hmC (5ghmC), bulky 5-position adducts and N4-modified base analogs which confer resistance to enzymatic deamination
Implementation Method 2
The biotin-modified adapters enable epigenetic sequencing workflows on solid phase
Data Source
AI summary
Compositions and methods for profiling methylation patterns present on target DNA in solution or affixed to a solid support are disclosed using enzymatic deamination-resistant and optionally also chemically resistant, oligonucleotides and nucleotides.