Thermostable T7 RNA Polymerase Variants for High-Temperature Transcription
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Solution Overview
Problem
Current in vitro transcription methods are limited to reaction temperatures below 45°C due to the inactivity of typical viral RNA polymerases at elevated temperatures, necessitating the identification of thermoactive and stable variants for conducting reactions at higher temperatures.
Innovation Solution
A bacteriophage RNA polymerase variant with specific amino acid substitutions, such as I109L, H205S, D388E, L534V, V567P, and G618Q, or additional substitutions like T75Q, A83K, E108L, K206P, V227I, and others, which confer increased thermostability and activity at elevated temperatures, allowing for RNA synthesis at temperatures of at least 45°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If typical viral RNA polymerases are used for in vitro transcription, then the reaction can be carried out at standard temperatures, but the polymerase becomes inactive at elevated temperatures above 45°C
Solution Approach 1:
The patent applies parameter changes by introducing specific amino acid substitutions (e.g., I109L, H205S, D388E, L534V, V567P, G618Q) into the T7 RNA polymerase sequence to modify its thermal stability parameters. These substitutions change the physical-chemical properties of the polymerase, enabling it to maintain structural integrity and catalytic activity at elevated temperatures up to 65°C or higher, thereby resolving the contradiction between temperature and polymerase activity.
2Temperature
If amino acid substitutions are introduced to increase thermostability, then the polymerase remains active at elevated temperatures, but the sequence identity to wild type decreases
Solution Approach 1:
The patent applies local quality by introducing amino acid substitutions at specific localized positions (109, 205, 388, 534, 567, 618) within the T7 RNA polymerase sequence rather than throughout the entire sequence. This targeted approach modifies only the critical regions needed for thermostability while preserving the overall sequence identity and maintaining compatibility with standard T7 promoters and transcription systems.
Data Source
AI summary
A bacteriophage RNA polymerase variant is provided. In some embodiments, the variant may have increased thermostability relative to the corresponding wild type bacteriophage RNA polymerase and/or wild type T7 RNA polymerase. Compositions, kits and methods that employ the variant are also provided.