Chromogenic identification of oligonucleotide-directed mutants

Area of Science:

• Molecular Biology
• Genetics
• Biotechnology

Background:

• Oligonucleotide-directed mutagenesis is crucial for genetic studies.
• Current methods for mutation screening can be labor-intensive and time-consuming.

Purpose of the Study:

• To develop a simple and efficient plaque color assay for identifying mutations in cloned DNA fragments.
• To enable the generation of both truncated and amino acid-substituted proteins.
• To facilitate the introduction of multiple mutations within a DNA sequence.

Main Methods:

• Fusing the target DNA sequence in-frame to the E.coli lacZ gene to create blue plaque phages.
• Introducing a stop codon to generate white plaque phages.
• Reverting the stop codon to yield blue plaque phages with desired mutations.

Main Results:

• The assay successfully identifies oligonucleotide-directed mutations.
• The method allows for the production of truncated proteins and amino acid substitutions.
• The cyclic nature of the assay permits repeated mutagenesis and screening.

Conclusions:

• This plaque color assay provides a simplified and efficient approach for site-directed mutagenesis.
• The method is versatile and applicable to various DNA fragments with an open reading frame.
• The technique was successfully applied to generate mutants in the yeast CUP1 gene.