Low-Temperature Library Prep Retains A/T-Rich Fragments
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Solution Overview
Problem
Current methods for preparing nucleic acid libraries, especially for short insert libraries, often result in the loss of A/T-rich fragments due to denaturation, leading to a non-representative library that does not accurately reflect the original sample, particularly when fragments are short.
Innovation Solution
A method is developed to prepare a library of template polynucleotides with uniform sequence representation by phosphorylating the 5' ends and incorporating nucleotide overhangs at the 3' ends of target polynucleotide duplex fragments at temperatures below 65°C, followed by ligation of adaptor polynucleotides to both ends, ensuring all fragments remain as duplexes and are representative of the original sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current methods are used to prepare nucleic acid libraries, then the library preparation process can be completed, but A/T-rich fragments are lost due to denaturation, resulting in non-representative library coverage
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature denaturation (94-98°C) to low-temperature processing (below 65°C, preferably 4-25°C). This parameter change prevents thermal denaturation of A/T-rich fragments while maintaining library preparation functionality, thereby improving representation accuracy and reducing fragment loss
Solution Approach 2:
The patent applies preliminary phosphorylation of 5' ends and addition of nucleotide overhangs at 3' ends before ligation, all at temperatures below 65°C. This preliminary action ensures fragments remain intact and representative before the ligation step, preventing loss of A/T-rich sequences that would otherwise denature during conventional high-temperature processing
2Productivity
If high temperature processing is used during library preparation, then ligation efficiency may be improved, but fragment denaturation occurs leading to loss of sequence representation
Solution Approach 1:
The patent redefines the temperature parameter range for library preparation from conventional high temperature (94-98°C) to low temperature (below 65°C). This change maintains sufficient ligation efficiency while preventing thermal denaturation, thereby achieving both productivity and manufacturing precision goals simultaneously
Solution Approach 2:
The patent uses adaptor polynucleotides as intermediaries that are ligated to both ends of target fragments at low temperatures. These adaptors facilitate subsequent amplification and sequencing while the low-temperature ligation process preserves the integrity and representation of original fragments, including A/T-rich sequences
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 method retains A/T-rich fragments and maintains full coverage of nucleic acid bases, ensuring that at least 99% of target fragment sequences are represented in the library, minimizing losses and maintaining sequence representation independent of sequence context.
Implementation Method 1
phosphorylating the 5' ends and incorporating nucleotide overhangs at the 3' ends of target polynucleotide duplex fragments
Implementation Method 2
ligation of adaptor polynucleotides to both ends
Data Source
AI summary
The invention relates to a method of preparing a library of template polynucleotides with uniform sequence representation and to use of a library of templates prepared using this method for solid-phase nucleic acid amplification. In particular, the invention relates to a method of preparing a library of template polynucleotides which have common sequences at their 5′ ends and at their 3′ ends, which contains even representation of all the fragments present in a starting sample of nucleic acid before fragmentation. The invention is especially applicable to the preparation of short insert libraries, where the sample fragments are less than 150 base pairs in length.