Hyperactive Tn5 Transposase Barcoding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current DNA sequencing library preparation methods using hyperactive Tn5 transposase for fragmentation and barcoding face inefficiencies due to low activity of wild-type end sequences and require additional mutations for enhanced activity, which complicates the process and reduces the reliability of DNA fragmentation and barcoding.
Innovation Solution
The method involves using a transposase loaded with oligonucleotide adaptors comprising a 3' single-stranded portion and a double-stranded portion, introducing double-stranded breaks into DNA, and ligating these adaptors to form barcoded DNA fragments, which are then amplified using PCR, allowing for efficient barcoding and sequencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type end sequences are used in Tn5 transposase, then the structure is simple and natural, but the transposition activity is low
Solution Approach 1:
The patent applies parameter changes by modifying the end sequences of the Tn5 transposase from wild-type to hyperactive variants. This involves changing specific nucleotide sequences and amino acid residues to enhance transposition activity. The hyperactive end sequences contain specific mutations that increase the catalytic efficiency of the transposase, resolving the contradiction between maintaining simple structure and achieving high reliability in transposition activity.
Solution Approach 2:
The patent employs composite materials by creating a hybrid transposase structure that combines elements from different Tn5 variants. The composite end sequences integrate functional domains from multiple sources to achieve both structural integrity and enhanced activity. This composite approach allows the transposase to maintain its fundamental structure while incorporating high-activity regions, thus resolving the contradiction between simplicity and reliability.
2Productivity
If hyperactive Tn5 transposase with multiple mutations is used, then transposition activity is enhanced, but the process complexity increases
Solution Approach 1:
The patent systematically changes parameters of the transposase by introducing specific point mutations at defined positions. Rather than random mutagenesis, the invention identifies critical residues and applies targeted amino acid substitutions that collectively enhance activity. This parameter-based approach optimizes DNA fragmentation efficiency while controlling the complexity of modifications required.
Solution Approach 2:
The patent applies segmentation by dividing the transposase structure into functional domains and optimizing them independently. The end sequences are treated as separate modular units that can be engineered and assembled. This segmentation allows systematic improvement of fragmentation efficiency through focused modifications of specific regions rather than requiring comprehensive changes throughout the entire protein structure.
3Reliability
If additional mutations are introduced to enhance transposase activity, then fragmentation reliability improves, but the risk of unintended effects increases
Solution Approach 1:
The patent applies controlled parameter changes by making specific, well-defined mutations at predetermined positions in the transposase sequence. Each mutation is selected based on its individual contribution to activity enhancement. This precise parameter control allows the invention to improve barcoding reliability while minimizing the risk of unintended effects, as opposed to using broadly mutated or randomly modified transposases.
Solution Approach 2:
The patent uses the hyperactive end sequences as intermediaries that mediate between the transposase core and the DNA substrate. These engineered end sequences act as buffered interfaces that enhance activity while isolating the core transposase from potential harmful interactions. The intermediary end sequences absorb and direct the effects of mutations, protecting the overall system from unintended consequences.
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 of DNA fragmentation and barcoding by improving the activity of the transposase, resulting in higher-quality DNA fragments suitable for sequencing while maintaining contiguity and allowing for the use of harsh reagents in droplet formation, improving reaction sensitivity.
Implementation Method 1
Transposition is a very infrequent event in vivo, and hyperactive mutants were historically derived by introducing three missense mutations in the 476 residues of the Tn5 protein
Implementation Method 2
the transposase introduces double-stranded breaks into the DNA, wherein each double-stranded break forms two DNA ends and the transposase ligates the first oligonucleotide to one strand of each DNA end
Implementation Method 3
hybridizing the 3' end of the first oligonucleotide primer (which is optionally released from the bead) to the 3' single stranded portion of the oligonucleotide adaptor
Implementation Method 4
contacting the reaction mixture with a ligase, thereby ligating the first oligonucleotide primer to the 5' end of the first oligonucleotide ligated to the DNA ends
Implementation Method 5
the amplifying comprises polymerase chain reaction
Data Source
AI summary
The methods and reagents are provided for barcoding and analysis of DNA samples using partition (e.g., droplet) technology while avoiding performing amplification in droplets.