One-Step DNA Cloning with Type IIs Enzymes
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Solution Overview
Problem
Current molecular cloning methods are inefficient for combining multiple polynucleotides into specialized vectors, particularly when restriction sites are not compatible, leading to lower efficiency and increased time and effort in creating desired DNA molecules.
Innovation Solution
A method utilizing typeIIs restriction enzymes that produce different length single-stranded overhangs, allowing for the assembly of three or more polynucleotides in a single reaction by DNA ligase, with specific combinations of enzymes like BsaI and BspQI or SapI, to join polynucleotides with precise overhangs, forming product polynucleotides with predetermined sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional restriction enzymes and ligases are used for subcloning, then simple subclonings can be done in one day, but combining more than two polynucleotides results in significantly lower efficiency and requires more time, effort and money
Solution Approach 1:
The patent merges multiple cloning steps into a single reaction by combining type IIs restriction enzymes and DNA ligases in one tube. Multiple polynucleotides with different overhangs are assembled simultaneously through directed ligation, eliminating the need for separate cloning reactions and significantly improving productivity while reducing time and effort.
Solution Approach 2:
The patent segments the cloning process into modular components with specific overhang types (4-base overhangs for vector/insert boundaries, 3-base overhangs for insert/insert joins). This segmentation allows independent optimization of each junction type while maintaining overall efficiency in a single reaction.
2Productivity
If multiple polynucleotides are combined in a single reaction, then productivity increases, but the complexity of the reaction system increases
Solution Approach 1:
The patent applies local quality by assigning specific overhang characteristics to specific locations in the polynucleotide assembly. Different segments have different overhang types (4-base vs 3-base) depending on their function, which simplifies the overall system by using standardized, location-specific interfaces rather than requiring complex heterogeneous interactions throughout.
Solution Approach 2:
The patent uses type IIs restriction enzyme sites as intermediary elements that facilitate controlled cleavage and ligation. These sites act as mediators between the polynucleotides, enabling directed assembly through a well-defined mechanism that reduces the effective complexity of the reaction system.
3Manufacturing precision
If typeIIs restriction enzymes producing different length overhangs are used, then specificity of joining polynucleotides improves, but the complexity of enzyme selection and protocol increases
Solution Approach 1:
The patent employs asymmetry by using different overhang lengths (4-base versus 3-base) at different positions in the assembly. This asymmetric design creates directional specificity that prevents incorrect ligation events, improving manufacturing precision while the asymmetry itself becomes part of the simplified standardized protocol.
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 enhances the efficiency and specificity of joining multiple polynucleotides, reducing the likelihood of undesired ligation and allowing for precise sequence assembly, thereby streamlining the cloning process and improving the production of desired DNA molecules.
Implementation Method 1
DNA digestion by one or more restriction enzymes that recognize a non-palindromic sequence, and that cleave outside their recognition sequences, for example typeIIs restriction enzymes
Implementation Method 2
a DNA ligase so that the polynucleotides are joined in a directed manner
Data Source
AI summary
Methods and kits for joining three or more polynucleotides to form a product polynucleotide are provided. Such a method includes forming a reaction mixture comprising (i) a vector fragment whose ends have four base overhangs resulting from cleavage of a vector with a first type IIs enzyme, (ii) a first insert nucleic acid with a four base overhang at one end resulting from cleavage by the first type IIs enzyme and a three base overhang at the other end resulting from cleavage by the second type IIs enzyme; and (iii) a second insert nucleic acid with a four base overhang at one end resulting from cleavage by the first type IIs enzyme and a three base overhang at the other end resulting from cleavage by the second type IIs enzyme, and (iv) a ligase. The four base overhangs of the vector ligate with the four base overhangs of the first and second inserts and the three base overhangs of the first and second inserts ligate with each other or three base overhangs of a spacer nucleic acid resulting from cleavage with the second type IIs enzyme to form a product polynucleotide in which the first and second insert nucleic acids are joined to the vector fragment.