Modified Polymerase Amino Acid Mutations for Sequencing Processivity
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Solution Overview
Problem
Current polymerases used in nucleic acid sequencing and library generation face limitations such as high dissociation rates from templates, incorrect nucleotide incorporation, and reduced processivity, which hinder the efficiency and accuracy of nucleotide polymerization reactions.
Innovation Solution
Development of modified polymerases with specific amino acid mutations that enhance dissociation time constants, processivity, and accuracy, allowing for increased nucleotide incorporation and improved sequencing performance, particularly in high ionic strength solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current polymerases are used in nucleic acid sequencing, then the sequencing process can be performed, but the polymerases exhibit high dissociation rates from templates which reduces processivity and sequencing efficiency
Solution Approach 1:
The patent applies parameter changes by introducing specific amino acid mutations (e.g., E446Q, H572R, H273R, H281A, H473R, Y477F, D480R, H528A) in the polymerase enzyme structure. These mutations alter the biochemical parameters of the polymerase, specifically enhancing its binding affinity to the template and increasing processivity. The mutations modify the enzyme's dissociation rate constant, allowing it to remain bound to the template for longer periods during sequencing reactions, thereby resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent applies local quality by making targeted amino acid substitutions at specific positions within the polymerase structure rather than modifying the entire enzyme. The mutations are localized to specific regions (e.g., fingers, palm, or thumb domains) where they can optimally enhance template binding without compromising other functional aspects of the polymerase. This localized modification approach allows the polymerase to maintain its catalytic activity while improving processivity.
2Productivity
If current polymerases are used for nucleotide polymerization, then the reaction can proceed, but incorrect nucleotide incorporation occurs which reduces sequencing accuracy
Solution Approach 1:
The patent applies parameter changes through amino acid mutations that selectively enhance the polymerase's ability to discriminate between correct and incorrect nucleotides. The mutations (such as H572R, H473R, H528A) alter the kinetic parameters of nucleotide incorporation, increasing the difference between the rate constants for correct (k_pol) and incorrect nucleotide incorporation. This selective parameter modification improves measurement precision while maintaining productivity.
3Adaptability or versatility
If standard polymerases are used in high ionic strength solutions, then the reaction conditions can be optimized, but the polymerase performance deteriorates due to reduced processivity
Solution Approach 1:
The patent applies parameter changes by introducing amino acid mutations that specifically enhance the polymerase's stability and binding affinity under high ionic strength conditions. The mutations (including E446Q, D480R, and combinations thereof) create electrostatic interactions or structural modifications that are resistant to salt-induced destabilization. This allows the polymerase to maintain high processivity and catalytic activity in high salt buffers, expanding the adaptability of the reaction conditions while preserving reliability.
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 modified polymerases demonstrate enhanced processivity, accuracy, and extended read lengths, significantly improving the efficiency and reliability of nucleic acid sequencing and library generation processes.
Implementation Method 1
a modified polymerase with a increased dissociation time constant relative to a reference polymerase; and polymerizing at least one of the one or more nucleotides onto an end of the primer using the modified polymerase
Data Source
AI summary
The present disclosure provides compositions, methods, kits, systems and apparatus that are useful for nucleic acid polymerization. In particular, modified polymerases and biologically active fragment thereof are provided that allow for nucleic acid amplification. In one aspect, the disclosure relates to modified polymerases useful for nucleic acid sequencing, genotyping, copy number variation analysis, paired-end sequencing and other forms of genetic analysis. In some aspects, the disclosure relates to modified polymerases useful for the generation of nucleic acid libraries or nucleic acid templates for use in various downstream processes. In some aspects, the disclosure relates to the identification of homologous amino acid mutations that can be transferred across classes or families of polymerases to provide novel polymerases with altered catalytic properties. In some aspects, the disclosure provides modified polymerases having enhanced catalytic properties as compared to a reference polymerase.