Small Molecule Ligation Enhancers for Nucleic Acid Cloning
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Solution Overview
Problem
The inefficiency of ligation reactions for blunt-ended or staggered-ended double-stranded polynucleotides, particularly due to interference from polyethylene glycol (PEG) which enhances ligation but inhibits subsequent electroporation, a crucial step in cloning and library preparation.
Innovation Solution
Incorporating small molecule ligation enhancers with a molecular weight of less than 1000 daltons, such as 1,2-propanediol (1,2-PrD), into the ligase reaction buffer to enhance intramolecular or intermolecular ligation efficiency without interfering with downstream processes like electroporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyethylene glycol (PEG) 6000 is used to enhance ligation of blunt-ended double-stranded polynucleotides, then ligation efficiency is improved, but subsequent electroporation of competent cells is interfered with
Solution Approach 1:
The patent changes the molecular weight parameter of the PEG compound from 6000 (PEG 6000) to lower values (PEG 200, PEG 400, or PEG 1000), thereby maintaining the ligation-enhancing property while eliminating the harmful interference with electroporation. This parameter change resolves the contradiction by finding an optimal molecular weight range that provides benefit without side effects.
Solution Approach 2:
The patent uses smaller, more volatile PEG molecules (PEG 200, PEG 400, PEG 1000) that can be more easily removed or do not persist in the reaction mixture, thereby avoiding long-term interference with subsequent electroporation steps. These smaller PEG molecules serve their enhancing function temporarily without creating lasting harmful effects.
2Object-generated harmful factors
If smaller molecules PEG 200 or PEG 400 are used, then interference with electroporation is reduced, but ligation enhancement effect is little or none
Solution Approach 1:
The patent identifies and tests a range of PEG molecular weights (200, 400, 1000, and 6000) to find the optimal parameter value that balances ligation enhancement with compatibility with downstream electroporation. The systematic variation of this molecular weight parameter allows optimization of both contradictory requirements.
Solution Approach 2:
The patent combines PEG molecules of different molecular weights in various formulations to achieve both ligation enhancement and electroporation compatibility. By creating composite PEG systems with specific molecular weight distributions, the patent optimizes the balance between enhancing ligation efficiency and avoiding interference with subsequent steps.
Data Source
AI summary
Compositions and methods are provided for enhancing enzymatic ligation between nucleic acid fragments that relies on one or more small molecule enhancers having a size of less than 1000 daltons. For example, enhancement of ligation efficiencies are observed for double- stranded nucleic acid fragments that are blunt-ended, have a single nucleotide overhang at the ligation end, or have staggered ends compared to ligation under similar conditions in the absence of the one or more small molecule ligation enhancer. The use of small molecule enhancers for ligating nucleic acids results in an increased number of transformed host cells after transformation with the ligated molecules. This enhancement can be observed with chemically transformed host cells and with host cells transformed by electroporation.