Syn5 RNA Polymerase Mutant Y564F for Homogeneous 3′-Termini

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Solution Overview

Problem

Current methods for synthesizing 2′-F RNAs face challenges in achieving precise 3′-termini homogeneity, which is crucial for applications like tRNA production and RNA probes, due to the existing RNA polymerases' inability to maintain high processivity and salt tolerance, leading to intermediate products and non-canonical nucleotide incorporation.

Innovation Solution

Employing the single-subunit RNA polymerase from marine cyanophage Syn5 (Syn5 RNAP) and its mutant Y564F, which exhibits high processivity and tolerance to salt, allowing for precise run-off transcripts with homogeneous 3′-termini, by using specific promoter sequences and optimized conditions such as Mn2+ and Mg2+ concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If standard T7 RNA polymerase is used for synthesizing 2′-F RNAs, then the enzyme can incorporate non-canonical nucleotides, but it produces intermediate products and fails to achieve precise 3′-termini homogeneity

Engineering Contradiction:

Improve3′-termini homogeneityVSAvoidprocessivity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by mutating specific amino acid residues in T7 RNA polymerase (Y639F, Y639A, Y639L substitutions) to alter the enzyme's properties. These mutations enable the polymerase to maintain high processivity and produce precise run-off transcripts with homogeneous 3′-termini while incorporating 2′-modified nucleotides, thereby resolving the contradiction between manufacturing precision and reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates mutant versions of T7 RNA polymerase that copy the essential function of the wild-type enzyme while improving specific properties. The mutant polymerases retain the ability to recognize T7 promoters and synthesize RNA but have enhanced processivity and salt tolerance, allowing them to produce full-length transcripts without intermediate products.

Inventive Principle:

Principle #26Copying

2Reliability

If T7 RNA polymerase is used under standard conditions, then transcription can proceed, but salt tolerance is limited and processivity is reduced

Engineering Contradiction:

Improvesalt toleranceVSAvoidtranscription efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent uses parameter changes by introducing amino acid substitutions (Y639F, Y639A, Y639L) that enhance the enzyme's salt tolerance. These mutations allow the polymerase to maintain high transcription efficiency and processivity even in the presence of elevated salt concentrations, enabling synthesis of long transcripts up to 2.7 kb with homogeneous 3′-termini.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple 2′-modified NTPs are included in the reaction, then diverse 2′-F RNA products can be synthesized, but discrimination between canonical and non-canonical nucleotides becomes substantial

Engineering Contradiction:

Improvenucleotide incorporation flexibilityVSAvoidnucleotide discrimination accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes through site-directed mutagenesis of the T7 RNA polymerase active site (Y639F, Y639A, Y639L mutations). These changes reduce the enzyme's discrimination against 2′-modified nucleotides while maintaining selectivity for canonical bases, enabling efficient incorporation of multiple 2′-F NTPs throughout the transcript without excessive misincorporation.

Inventive Principle:

Principle #35Parameter changes

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 Syn5 RNAP and its mutant Y564F enable the production of transcripts with greater than 90% homogeneity in 3′-termini, reducing nucleotide overhangs and improving the precision of RNA synthesis for applications requiring exact 3′-termini, such as tRNA and RNA probes.

Implementation Method 1

A single subunit DNA-dependent RNAP was identified and purified to apparent homogeneity from cyanophage Syn5... Syn5 RNAP catalyzes RNA synthesis over a wide range of temperature and salinity

Methodology Applied

Scientific EffectEnzyme catalysis: Enzyme