Split Polymerase Nucleotide Incorporation Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current DNA polymerases exhibit high discrimination against unconventional nucleotides, leading to inefficient incorporation of dual-labeled nucleotide analogs and ribonucleotides, which limits their use in applications like DNA sequencing and PCR, and require high concentrations, increasing costs and background noise.
Innovation Solution
Introducing non-natural splits into DNA polymerases to reduce substrate interaction constraints, allowing for improved incorporation of non-natural nucleotides by modifying the polymerase structure, such as in the fingers domain, to create split polymerases with enhanced activity for dual-labeled nucleotides and increased thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional DNA polymerases are used, then standard deoxynucleotide incorporation is efficient, but unconventional nucleotide incorporation is inefficient due to high discrimination
Solution Approach 1:
The polymerase enzyme is divided into two separate polypeptides (N-terminal and C-terminal fragments) that can function independently or associate to form a complete polymerase. This segmentation allows independent optimization of each fragment's properties, enabling the N-terminal fragment to enhance unconventional nucleotide incorporation while the C-terminal fragment maintains structural stability and fidelity.
Solution Approach 2:
Specific regions of the polymerase are modified with different properties - the N-terminal fragment contains mutations (such as Q484R in Pfu polymerase) that locally enhance unconventional nucleotide incorporation, while the C-terminal fragment maintains the original high-fidelity characteristics. This creates local quality differences within the polymerase structure.
2Quantity of substance
If high concentrations of unconventional nucleotides are used to compensate for low incorporation efficiency, then labeling can be achieved, but background noise and costs increase
Solution Approach 1:
The polymerase enzyme parameters are modified through protein engineering - specific amino acid mutations are introduced in the N-terminal fragment to change its nucleotide recognition properties. This parameter change in the enzyme itself (rather than changing nucleotide concentrations) enables efficient incorporation of unconventional nucleotides at standard concentrations, avoiding background noise and cost issues.
3Adaptability or versatility
If polymerase structure is modified to improve unconventional nucleotide incorporation, then dual-labeled nucleotide utilization increases, but structural stability may be compromised
Solution Approach 1:
By segmenting the polymerase into N-terminal and C-terminal fragments, the structural stability function is separated from the substrate recognition function. The C-terminal fragment can be designed to maintain structural stability while the N-terminal fragment provides enhanced substrate utilization. This segmentation allows independent optimization of stability and adaptability.
Solution Approach 2:
The polymerase is constructed as a composite system combining two different polypeptide fragments with complementary functions. The N-terminal fragment contributes to substrate recognition and incorporation efficiency, while the C-terminal fragment contributes to structural stability. Together they form a functional composite enzyme that achieves both goals.
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 split polymerases demonstrate increased utilization of non-natural nucleotides, reducing the need for high concentrations and background noise, enhancing the efficiency and cost-effectiveness of DNA sequencing and PCR processes while maintaining stability.
Implementation Method 1
a polymerase enzyme that catalyzes the template-dependent incorporation of the unconventional nucleotide(s) into the newly synthesized complementary strand
Implementation Method 2
Amino acids within the active site of polymerases form a specific binding pocket that favors the placement of the correct complementary nucleotide opposite the template nucleotide
Data Source
AI summary
The invention relates to compositions and methods utilizing split polymerase enzymes composed of at least two discrete polypeptides that stably associate to form a single polymerase. The invention further relates to nucleic acid constructs for expressing the split polymerases of the invention, and methods for using the split polymerases of the invention. The enzymes of the invention are useful in many applications calling for the detectable labeling of nucleic acids and are particularly useful in quantitative PCR (QPCR) and DNA sequencing applications.