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Simple biological assay for the error rate upon cloning of synthetic oligodeoxyribonucleotides
W Mandecki1, M A Shallcross, T J Kavanaugh
1Abbott Laboratories, Corporate Molecular Biology, Abbott Park, IL 60064-3500.
Abstract:
A method was developed for determination of the rate of undesired point mutations upon cloning of synthetic DNA. The method relies on cloning of an oligonucleotide(s) into the E. coli alkaline phosphatase gene inactivated due to a small deletion within the active site. The oligonucleotide adds back the deleted sequence, but simultaneously introduces a missense mutation at a critical position. The activity of the enzyme is restored only if there is a predefined sequence change within the codon specifying an essential residue of the active site. The clones carrying the reactivated gene are detected by colony color screening on plates. The method is fast and simple, does not require specialized equipment nor enzymatic reactions, although a separate oligonucleotide needs to be provided for each sequence change to be evaluated. The procedure allows for the use of crude extracts of oligonucleotides and distinguishes between different types of sequence changes.
Insights
A new method detects DNA mutation rates during synthetic DNA cloning. It uses a modified E. coli alkaline phosphatase gene, enabling simple colony screening for accurate mutation analysis.
Area of Science:
- Molecular Biology
- Synthetic Biology
- Biotechnology
Background:
- Accurate determination of mutation rates is crucial for synthetic DNA applications.
- Existing methods for detecting mutations during DNA cloning can be complex or require specialized equipment.
Purpose of the Study:
- To develop a fast, simple, and cost-effective method for quantifying undesired point mutations introduced during synthetic DNA cloning.
- To enable reliable screening of bacterial clones for specific sequence alterations.
Main Methods:
- Cloning synthetic oligonucleotides into a specifically inactivated E. coli alkaline phosphatase gene.
- Utilizing a missense mutation strategy where enzyme activity is restored only by predefined sequence changes.
- Employing colony color screening on agar plates for clone selection.
Main Results:
- The developed method successfully detects and quantifies point mutations introduced during DNA cloning.
- The system allows for the use of crude oligonucleotide extracts, simplifying the process.
- Different types of sequence changes can be distinguished through the screening method.
Conclusions:
- This method provides a robust approach for assessing the fidelity of synthetic DNA cloning.
- The technique is suitable for routine use in molecular biology labs without specialized infrastructure.
- It facilitates the accurate evaluation of sequence changes in synthetic DNA constructs.