AEGIS Nucleotides for Reliable Ultra-Large DNA Assembly
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Solution Overview
Problem
Current methods for assembling large DNA molecules from multiple single-stranded DNA fragments face challenges due to the low information density of natural DNA, non-uniform binding of nucleotide pairs, and issues like hairpin formation and non-canonical interactions, making it difficult to achieve reliable self-assembly of thousands of nucleobase pairs.
Innovation Solution
The use of artificially expanded genetic information systems (AEGIS) that add up to eight new nucleotides to the standard DNA alphabet, forming uniformly strong base pairs and avoiding non-canonical interactions, allowing for the assembly of over 12 single-stranded DNA fragments into large synthetic DNA constructs by enabling uniform hybridization and preventing hairpin formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard DNA fragments are used for self-assembly, then the process is simple and inexpensive, but the assembly reliability deteriorates due to non-uniform base pair binding and off-target interactions
Solution Approach 1:
The patent modifies the chemical parameters of DNA base pairs by introducing isoguanine and isocytosine nucleotides that form uniformly strong triple-hydrogen bond pairs. This parameter change eliminates the non-uniform binding strength problem of standard DNA while maintaining the self-assembly process, thereby improving assembly reliability without sacrificing simplicity
Solution Approach 2:
The patent creates a composite nucleic acid system by combining standard DNA nucleotides with synthetic isoguanine-isocytosine pairs. This composite material approach allows the system to retain the desirable properties of standard DNA (simplicity of handling) while introducing the uniform binding strength needed for reliable assembly of many fragments
2Quantity of substance
If more DNA fragments are assembled together, then the information density increases, but the likelihood of off-target Watson-Crick hybridization and non-canonical interactions increases
Solution Approach 1:
By changing the hydrogen bonding parameters to use isoguanine-isocytosine pairs with uniform triple-bond strength, the patent eliminates the variability that causes off-target binding. This allows a larger number of fragments to be assembled together without increasing off-target hybridization errors
Solution Approach 2:
The patent converts the potential harm of increased fragment数量 into a benefit by using the expanded nucleotide alphabet to create highly specific isoguanine-isocytosine pairing. The uniform binding strength that could potentially cause mispairing is instead used to ensure correct pairing through increased specificity
3Device complexity
If standard DNA nucleotides are used, then the system is simple and well-understood, but the information density is too low to support assembly of thousands of fragments
Solution Approach 1:
The patent creates a composite genetic system that combines standard DNA with synthetic isoguanine-isocytosine nucleotides. This composite approach increases information density by adding two new nucleotide types while maintaining compatibility with standard DNA handling and processing methods
Solution Approach 2:
The patent adds a new dimension to the genetic alphabet by introducing isoguanine and isocytosine nucleotides that pair through triple hydrogen bonds. This dimensional expansion of the nucleotide space increases information density from 2 bits per base pair to potentially higher values, enabling assembly of thousands of fragments
4Reliability
If uniform base pair strength is achieved through isoguanine-isocytosine pairs, then assembly reliability improves, but the cost and complexity of synthesis increase
Solution Approach 1:
The patent modifies the chemical parameters of base pairing to use isoguanine-isocytosine pairs with uniform triple-hydrogen bond strength. While this increases synthesis complexity, it enables reliable assembly of large numbers of fragments, ultimately reducing costs by eliminating the need for extensive purification and verification steps
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
This approach enables the efficient assembly of large DNA constructs, such as genes, plasmids, and artificial chromosomes, by increasing information density and preventing off-target mismatches, thereby facilitating the creation of desired DNA products with high accuracy and reliability.
Implementation Method 1
assembly of large numbers of short single stranded DNA molecules
Implementation Method 2
designed solely by applying Watson-Crick rules
Implementation Method 3
AEGIS pairs are all joined by three hydrogen bonds
Implementation Method 4
forming uniformly strong base pairs
Implementation Method 5
Hairpin structures formed by a single strand
Data Source
AI summary
This invention provides processes to assemble many (greater than 20) partially overlapping single stranded DNA molecules (fragments) having preselected sequences, followed by extension of those strands that hybridize at terminal overlap regions, and ligation of the extend products, creating a double-stranded DNA assembly. These processes use non-standard nucleotides carrying heterocyclic nucleobase analogs that implement non-standard hydrogen bonding patterns; these allow controlled annealing of the single stranded fragments via Watson-Crick rules, with less or no interference from a range of non-Watson Crick interactions, hairpin formations, or off-target hybridization displayed by standard nucleobases. This process includes an optional conversion step that replaces non-standard nucleobase pairs with standard nucleobase pairs, generating large synthetic DNA (LS-DNA) molecules containing only natural nucleotides. As useful application, this invention allows the assembly of genes encoding whole proteins (typically 1000-3000 nucleotide pairs) from a collection of single stranded DNA fragments at reduced cost and effort.