A high-efficiency method to replace essential genes with mutant alleles in yeast.

Area of Science:

• Molecular Biology
• Genetics

Background:

• Characterizing essential genes requires tools like temperature-sensitive (TS), internally deleted, and truncated alleles.
• Existing methods for integrating mutant alleles can be inefficient, especially for alleles with compromised function or multiple mutations.

Purpose of the Study:

• To develop a straightforward and efficient method for replacing wild-type genes with mutant alleles at the endogenous locus.
• To facilitate the characterization of essential genes using various mutant alleles.

Main Methods:

• A selectable marker disrupts the essential gene, while viability is maintained by a plasmid with the wild-type gene and ADE3.
• Mutant alleles are cloned into an integratable vector with a selectable/counter-selectable marker (e.g., URA3) and transformed.
• Integration occurs at flanking regions of the open reading frame (ORF); transformants lose the plasmid and display the mutant phenotype.
• Optional 5-fluoroorotic acid (5-FOA) selection recycles markers and confirms the mutant allele at the endogenous locus.

Main Results:

• The method successfully integrated a TS allele of SPC110 that resisted standard integration methods.
• The developed technique provides an efficient alternative to two-step methods for integrating compromised or multi-mutated alleles.
• Identified transformants by white sectoring colonies and confirmed mutant phenotypes.

Conclusions:

• The new method offers a robust and efficient way to integrate mutant alleles, including TS alleles, into the endogenous locus.
• This approach simplifies the characterization of essential genes by enabling the integration of previously difficult-to-integrate alleles.
• The technique is broadly applicable for genetic studies requiring precise allelic replacement.