Pfu Polymerase Mutants for One-Step High-Temperature RT-PCR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current RT-qPCR methods for RNA virus detection require separate use of reverse transcriptase and Taq DNA polymerase, leading to inefficiencies due to intolerance to high temperatures, complex sample pretreatment, and reduced sensitivity under low template conditions.
Innovation Solution
Development of Pfu DNA polymerase mutants with enhanced reverse transcriptase activity, allowing for one-step RT-PCR using a single enzyme, specifically through rational design and mutation of Pfu DNA polymerase to achieve stable and efficient reverse transcription and PCR amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reverse transcriptase and Taq DNA polymerase are used separately for RT-qPCR, then reverse transcription can be performed, but the process becomes cumbersome and time-consuming due to separate steps and sample pretreatment
Solution Approach 1:
The patent combines reverse transcriptase and Taq DNA polymerase activities into a single chimeric enzyme by fusing the reverse transcriptase domain (from MMLV) with the Taq DNA polymerase domain, enabling both reverse transcription and PCR amplification to be performed in one step with a single enzyme, thereby simplifying the detection process and improving efficiency
Solution Approach 2:
The chimeric enzyme is designed to perform multiple functions: it can catalyze both reverse transcription of RNA to cDNA and subsequent PCR amplification of DNA templates, making it a universal enzyme for the entire RT-qPCR process and eliminating the need for separate enzymes and steps
2Productivity
If reverse transcriptase is used at lower temperature first, then temperature must be increased for PCR, but this multi-step temperature protocol prolongs the detection time
Solution Approach 1:
The chimeric enzyme enables merging of reverse transcription and PCR amplification into a single isothermal reaction step performed at 68°C, eliminating the need for temperature cycling between reverse transcription and PCR steps, thereby significantly reducing detection time
3Measurement precision
If Taq DNA polymerase is present during reverse transcription, then it can bind the template, but this competes with reverse transcriptase and reduces detection sensitivity under low template conditions
Solution Approach 1:
The chimeric enzyme combines both reverse transcriptase and Taq polymerase activities in a single molecular entity, ensuring that both activities are present in equimolar amounts and work cooperatively on the same template without competitive inhibition, thereby maintaining high detection sensitivity even under low template conditions
4Reliability
If separate reverse transcriptase and Taq DNA polymerase are used, then each enzyme can perform its function, but the activity of both enzymes is affected after mixing, requiring prolonged reverse transcription time
Solution Approach 1:
The chimeric enzyme structure ensures that reverse transcriptase and Taq polymerase activities are integrated in a single protein molecule, eliminating inter-enzyme interference and activity loss that occurs when separate enzymes are mixed, thereby maintaining optimal activity levels and reducing required reaction time
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 Pfu DNA polymerase mutants, particularly K118I/N713V, enable efficient and high-fidelity cDNA synthesis from RNA templates, simplifying the detection process and improving sensitivity and efficiency of RNA detection.
Implementation Method 1
Pfu DNA polymerase mutants with reverse transcriptase activity... catalyze the polymerization of deoxyribonucleotides (DNA) in the 5′→3′ direction... enable efficient and high-fidelity cDNA synthesis from RNA templates
Data Source
AI summary
Pfu DNA polymerase mutants with reverse transcriptase activity and their applications are provided. The Pfu DNA polymerase mutants include K467R/F588L/W769R, R382H/Y385H/V390I, I38L/R97M, E665K/E735K, K118I/N713V, with K118I/N713V showing the strongest reverse transcription activity. These Pfu DNA polymerase mutants still retain the polymerase activity of wild-type enzymes, thus providing higher assurance compared to traditional reverse transcriptase. Meanwhile, these Pfu DNA polymerase mutants exhibit high heat tolerance. Therefore, these Pfu DNA polymerase mutants can efficiently and high fidelity generate cDNA using RNA as a substrate, and further amplify the cDNA under conventional PCR reaction conditions without the need for additional reverse transcriptase, achieving a “one-step” RT-PCR process.