Non-LTR Reverse Transcriptase for Continuous cDNA Across Gapped Templates
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Solution Overview
Problem
Existing methods struggle to efficiently convert RNA into complementary DNA (cDNA) for applications like PCR-based sequence detection, hybridization-based microarray profiling, and high-throughput sequencing due to challenges in unbiased and unaltered sequence recovery from information-rich RNA.
Innovation Solution
Utilizing a truncated eukaryotic non-long terminal repeat reverse transcriptase (non-LTR RT) protein with mutations to abolish endonuclease function, combined with manganese ions and specific buffer conditions, to extend the 3' ends of nucleic acids and synthesize cDNA across non-continuous templates without retroviral interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reverse transcriptase methods are used for RNA to cDNA conversion, then cDNA synthesis can be achieved, but the process suffers from bias and alterations that prevent unbiased sequence recovery
Solution Approach 1:
The invention extracts and removes the endonuclease domain from the reverse transcriptase protein, creating a truncated RT protein that lacks endonuclease activity. This extraction of the harmful functional domain resolves the contradiction by eliminating the source of DNA degradation and bias while preserving the cDNA synthesis capability.
Solution Approach 2:
The invention changes the functional parameters of the reverse transcriptase by mutating specific amino acid residues in the endonuclease domain to abolish its activity. This parameter change transforms the enzyme from having dual functionality (reverse transcription and endonuclease activity) to having only reverse transcription activity, thereby achieving unbiased sequence recovery.
2Reliability
If full-length non-LTR RT protein is used, then endonuclease activity is present for potential template processing, but this activity causes DNA degradation and reduces cDNA synthesis fidelity
Solution Approach 1:
The invention converts the potentially harmful endonuclease activity into a benefit by selectively abolishing only the harmful DNA-degrading function while preserving the essential reverse transcription function. The mutated endonuclease domain can still bind to templates but cannot cleave DNA, thus converting a harmful factor into a neutral or potentially beneficial structural element.
3Productivity
If retroviral RT proteins are used for cDNA synthesis, then high reverse transcription efficiency is achieved, but retroviral interference and contamination issues arise
Solution Approach 1:
The invention uses a non-retroviral, non-LTR reverse transcriptase protein that is functionally sufficient for cDNA synthesis but lacks the pathogenic and interfering characteristics of retroviral RT proteins. This alternative enzyme serves as a disposable, safe replacement that achieves the necessary productivity without the harmful retroviral elements.
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
Enables high-yield, controlled, and continuous cDNA synthesis across non-continuous templates, facilitating efficient PCR-free cDNA library preparation for sequencing and hybridization analysis.
Implementation Method 1
synthesize cDNA across non-continuous templates
Implementation Method 2
truncated eukaryotic non-long terminal repeat reverse transcriptase (non-LTR RT) protein
Implementation Method 3
combined with manganese ions and specific buffer conditions, to extend the 3' ends of nucleic acids
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
The invention provides compositions and methods for nucleic acid synthesis, including ordered and continuous complementary DNA (cDNA) synthesis across non-continuous templates using a modified eukaryotic non-long terminal repeat reverse transcriptase (non-LTR RT) protein.