Engineered Reverse Transcriptase Variants for Low-Temperature cDNA Synthesis
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Solution Overview
Problem
Current reverse transcriptase enzymes face challenges in efficiently converting RNA to DNA at low temperatures due to RNA secondary structures and inhibition by compounds in biological samples, particularly in small volume reactions like single cell profiling, where they exhibit reduced activity and processivity.
Innovation Solution
Engineered reverse transcriptase variants with specific mutations, such as E69K, L139P, E302R, T306K, W313F, T330P, and others, are developed to enhance thermoreactivity, processivity, and resistance to inhibitors, improving transcription efficiency and template switching in small volume reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If wild-type reverse transcriptase is used at low temperatures, then reaction conditions are favorable for enzyme activity, but RNA secondary structures form and inhibit transcription efficiency
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of reverse transcriptase through multiple mutations (e.g., M39V, M66L, E69K, L139P, E302R, T306K, W313F, T330P, N454K) to alter the enzyme's physical-chemical properties. These mutations enable the enzyme to function effectively at elevated temperatures (50-70°C) where RNA secondary structures are denatured, thus resolving the contradiction between temperature and transcription efficiency.
2Quantity of substance
If small reaction volumes are used for single cell profiling, then sample consumption is reduced, but inhibitor concentration increases and reduces enzyme activity
Solution Approach 1:
The patent uses parameter changes by engineering the reverse transcriptase with multiple amino acid mutations that enhance its resistance to inhibitors. Mutations such as M39V, M66L, and others modify the enzyme's structure to reduce inhibitor binding or increase catalytic efficiency in the presence of inhibitors, allowing effective operation in small-volume reactions where inhibitor concentrations are high.
3Device complexity
If wild-type reverse transcriptase is used in chemically crowded conditions, then reaction simplicity is maintained, but enzyme processivity and thermostability are reduced
Solution Approach 1:
The patent applies parameter changes through comprehensive amino acid sequence engineering with multiple mutations (including M39V, M66L, E69K, L139P, E302R, T306K, W313F, T330P, N454K, and others) that collectively enhance enzyme processivity, thermostability, and inhibitor resistance. These changes allow the enzyme to maintain high reliability in chemically crowded conditions without requiring complex reaction protocols.
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 engineered reverse transcriptase variants demonstrate significantly improved transcription efficiency and template switching, overcoming the limitations of wild-type enzymes in small volume reactions and chemically crowded conditions, with enhanced thermostability and resistance to inhibitors.
Implementation Method 1
engineered reverse transcriptase comprising the amino acid sequence of SEQ ID NO: 15, and further comprising a combination of mutations selected from: (a) E69K, L139P, E302R, T306K, W313F, T330P, N454K; and one or more of M39V, P47L, M66L, F155Y, D200N, D200E, H204R, G429S, L435G, L435K, P448A, D449G, H503V, D524N, T542D, E545G, D583N, H594Q, L603W, L603F, E607K, E607G, P627S, H634Y, H638G, A644V, D653H, K658R and L671P
Data Source
AI summary
The disclosure provides engineered reverse transcriptase enzymes that have been modified to enhance their enzymatic to increase their processivity, template switching efficiency, binding affinity, and/or transcription efficiency and to decrease their RNAse H activity. The disclosure further provides compositions and kits comprising the engineered reverse transcriptase enzymes and methods of producing, amplifying or sequencing nucleic acid molecules using these reverse transcriptase enzymes.