Circular DNA Amplification with SSB Protein
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Solution Overview
Problem
Existing DNA amplification methods are laborious, expensive, time-consuming, inefficient, and often favor amplification of linear DNA over circular DNA, requiring specific sequence knowledge and leading to contamination risks.
Innovation Solution
Incorporating Single Strand Binding (SSB) protein into the reaction mixture with Phi29 DNA polymerase enhances the yield and purity of circular DNA amplification products, particularly for mitochondrial DNA, by selectively amplifying circular DNA over linear DNA, even in samples containing both forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional DNA amplification methods are used, then amplification can be performed, but the yield and purity of circular DNA products are low
Solution Approach 1:
The patent introduces SSB protein as an intermediary component in the amplification reaction system. The SSB protein specifically binds to and stabilizes single-stranded circular DNA intermediates, preventing their degradation or conversion to linear forms. This intermediary action enhances both the yield and purity of circular DNA amplification products by creating a protective environment for the desired product throughout the amplification process.
2Productivity
If Phi29 DNA polymerase is used alone, then amplification occurs, but linear DNA is amplified preferentially over circular DNA
Solution Approach 1:
The patent modifies the reaction conditions by adding SSB protein, which changes the physical-chemical parameters of the amplification system. The SSB protein alters the binding affinity and stability of DNA intermediates, creating conditions that favor circular DNA amplification. This parameter change transforms the selectivity of the Phi29 DNA polymerase system from preferential linear DNA amplification to preferential circular DNA amplification while maintaining high productivity.
3Measurement precision
If multiple primers are used in MPA method, then sensitivity to low concentration targets improves, but risk of contamination increases
Solution Approach 1:
The SSB protein acts as a protective intermediary that stabilizes the multiple primers used in the MPA method. By binding to single-stranded DNA regions, the SSB protein protects primers from degradation and non-specific binding, maintaining their functionality throughout the amplification process. This reduces the need for excessive primer concentrations and associated contamination risks while preserving the high sensitivity advantage of using multiple primers.
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
The use of SSB in DNA amplification reactions significantly increases the yield of circular DNA products, achieving up to 1500-fold enrichment of mitochondrial DNA, allowing for direct sequencing and reducing contamination risks, while maintaining the physical properties of the starting template.
Implementation Method 1
Incorporating Single Strand Binding (SSB) protein into the reaction mixture with Phi29 DNA polymerase enhances the yield and purity of circular DNA amplification products
Implementation Method 2
DNA polymerase is added. The amplification target circle (ATC) forms a template on which new DNA is made, thereby extending the primer sequence
Implementation Method 3
Exponential rolling circle amplification (ERCA) employs a cascade of strand displacement reactions
Data Source
AI summary
A method is disclosed in which circular DNA molecules are amplified preferentially in a mixture of circular DNA molecules and linear DNA molecules by the inclusion of single strand DNA binding protein.