Single-Molecule Methylation Sequencing Kinetics

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Solution Overview

Problem

Current methods for determining genome-wide methylation patterns, such as bisulfite sequencing, face challenges including high sample preparation time, DNA degradation, and limitations in sequencing technologies that hinder accurate profiling, especially in repetitive genomic regions and de novo methylation analysis.

Innovation Solution

A direct methylation sequencing technology that monitors the kinetics of single polymerase molecules in real-time, allowing for fast and economical analysis of methylation patterns, even in repetitive regions, by detecting changes indicative of methylated bases during nucleic acid synthesis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If bisulfite sequencing is used for methylation profiling, then single-nucleotide resolution methylation analysis is achieved, but DNA degradation occurs due to harsh reaction conditions

Engineering Contradiction:
Improvesingle-nucleotide resolution methylation analysisVSAvoidDNA degradation
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the harsh chemical bisulfite treatment system with a single-molecule sequencing system that directly reads methylation status without chemical conversion. This substitution eliminates the harmful chemical reactions that cause DNA degradation while maintaining single-nucleotide resolution through direct detection of methylated bases during sequencing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a single-molecule sequencing technology as an intermediary between the DNA template and the methylation detection system. This intermediary system allows direct observation of methylation status without requiring the harsh bisulfite chemical transformation, thus avoiding DNA degradation while preserving measurement precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If bisulfite sequencing is used for methylation profiling, then methylation status can be determined, but large starting amounts of sample are required due to DNA degradation

Engineering Contradiction:
Improvemethylation status determinationVSAvoidstarting amount of sample
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent replaces the bisulfite sequencing system with single-molecule sequencing, which eliminates the need for large sample amounts. By directly sequencing individual molecules and detecting methylation status at the single-molecule level, the system achieves accurate methylation profiling without requiring the large starting amounts of DNA needed to compensate for bisulfite-induced degradation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses digital sequencing reads as copies of the original DNA methylation information. Instead of relying on physical DNA copies that degrade during bisulfite treatment, the system creates digital representations of methylation status through single-molecule sequencing, eliminating the need for large physical sample amounts.

Inventive Principle:
Principle #26Copying

3Measurement precision

If current sequencing technologies are used for methylation profiling, then methylation patterns can be analyzed, but read lengths are short which hinders accurate profiling in repetitive regions

Engineering Contradiction:
Improvemethylation pattern analysisVSAvoidread length
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The patent replaces conventional short-read sequencing with single-molecule sequencing that generates long reads. This substitution enables accurate methylation profiling in repetitive genomic regions by maintaining long read lengths that can span repetitive elements, allowing unambiguous mapping and analysis of methylation patterns that short reads cannot resolve.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If bulk reactions are used for biological process monitoring, then general trends can be ascertained, but information about individual molecular complexes is lost

Engineering Contradiction:
Improvebulk reaction analysis efficiencyVSAvoidinformation about individual molecular complexes
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent segments the analysis from bulk population-level measurement to single-molecule-level measurement. By sequencing individual DNA molecules and detecting methylation status at each molecule, the system preserves information about individual molecular complexes while maintaining the efficiency of high-throughput single-molecule sequencing. This segmentation eliminates the information loss inherent in bulk averaging.

Inventive Principle:
Principle #1Segmentation

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 provides high-resolution, efficient detection of methylated bases, enhancing the understanding of DNA methylation's role in human health and overcoming limitations of existing technologies.

Implementation Method 1

providing an enzyme capable of processing the template nucleic acid in a single molecule sequencing reaction

Methodology Applied
Scientific EffectNucleic acid synthesis:

Implementation Method 2

monitoring processing of the template nucleic acid by the enzyme; and detecting a change in the processing, wherein the change is indicative of the modification and comprises a kinetic difference

Methodology Applied
Scientific EffectKinetic detection:

Data Source

PatentEP2370598B1Classification of nucleic acid templates
Publication Date: 2017.02.15 PACIFIC BIOSCIENCES OF CALIFORNIA INC
  • EP2370598B1 patent drawingFigure 1A~1B
  • EP2370598B1 patent drawingFigure 2A~2B
  • EP2370598B1 patent drawingFigure 3

AI summary

Methods, compositions, and systems are provided for characterization of modified nucleic acids. In certain preferred embodiments, single molecule sequencing methods are provided for identification of modified nucleotides within nucleic acid sequences. Modifications detectable by the methods provided herein include chemically modified bases, enzymatically modified bases, abasic sites, non-natural bases, secondary structures, and agents bound to a template nucleic acid.