Mapping epigenetic mutations in fission yeast using whole-genome next-generation sequencing

Area of Science:

• Molecular Biology
• Genetics
• Epigenetics

Background:

• Fission yeast is a key model organism for epigenetic studies.
• Identifying genes responsible for epigenetic phenotypes can be challenging due to instability.
• Complementation of epigenetic defects with genomic libraries is often difficult.

Purpose of the Study:

• To identify novel mutants involved in heterochromatic silencing in fission yeast.
• To overcome challenges in identifying genes responsible for unstable epigenetic phenotypes.
• To leverage next-generation sequencing for enhanced yeast genetics.

Main Methods:

• Genome resequencing following mutagenesis to identify novel mutants.
• Identification of candidate genes through functional single base changes linked to mutations.
• Reconstitution of candidate genes in a wild-type strain to confirm the mutant phenotype.

Main Results:

• A novel mutant (swi*603) affecting heterochromatic silencing was identified.
• A weak allele of ubc4, encoding an essential E2 ubiquitin ligase, was found to cause the swi*603 phenotype.
• The study demonstrates the utility of genome resequencing for isolating subtle and quantitative alleles.

Conclusions:

• Next-generation genomic resequencing significantly enhances the capabilities of yeast genetics.
• This approach facilitates the isolation of subtle alleles of essential genes and epigenetic modifiers.
• The findings pave the way for identifying enhancers and suppressors of heterochromatic silencing.