Minisatellites, one of the major classes of repetitive DNA sequences in eukaryotic genomes, are stable in somatic cells but destabilize during meiosis. We previously established a yeast model system by inserting the human Ha-ras/HRAS1 minisatellite into the HIS4 promoter and demonstrated that our system recapitulates all of the phenotypes associated with the human minisatellite. Here we demonstrate that meiotic minisatellite tract-length changes are half as frequent in diploid cells harboring heterozygous HRAS1 minisatellite tracts in which the two tracts differ by only two bases when compared to a strain with homozygous minisatellite tracts. Further, this decrease in alteration frequency is entirely dependent on DNA mismatch repair. In contrast, in a diploid strain containing heterozygous minisatellite tract alleles differing in length by three complete repeats, length alterations are observed at twice the frequency seen in a strain with homozygous tracts. Alterations consist of previously undetectable gene conversion events, plus nonparental length alteration events seen previously in strains with homozygous tracts. A strain containing tracts with both base and length heterozygosity exhibits the same level of alteration as a strain containing only length heterozygosity, indicating that base heterozygosity-dependent tract stabilization does not affect tract-length alterations occurring by gene conversion.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|