Homologous recombinational repair of double-strand breaks in yeast is enhanced by MAT heterozygosity through yKU-dependent and -independent mechanisms
| Autor: | Sandra L. Barton, Jac A. Nickoloff, Guru Jot Khalsa, Jennifer A. Clikeman |
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| Rok vydání: | 2001 |
| Předmět: |
Heterozygote
Saccharomyces cerevisiae Proteins Cell division DNA Repair DNA damage DNA repair RAD52 Biology Haploidy Loss of heterozygosity Genetics Homologous chromosome Ku Autoantigen Alleles Recombination Genetic Models Genetic fungi Wild type DNA Helicases Nuclear Proteins Antigens Nuclear Molecular biology Diploidy DNA-Binding Proteins enzymes and coenzymes (carbohydrates) Mutation Homologous recombination Mating Factor Peptides Cell Division DNA Damage Plasmids Protein Binding Research Article |
| Zdroj: | Genetics. 157(2) |
| ISSN: | 0016-6731 |
| Popis: | DNA double-strand breaks (DSBs) are repaired by homologous recombination (HR) and nonhomologous end-joining (NHEJ). NHEJ in yeast chromosomes has been observed only when HR is blocked, as in rad52 mutants or in the absence of a homologous repair template. We detected yKu70p-dependent imprecise NHEJ at a frequency of ∼0.1% in HR-competent Rad+ haploid cells. Interestingly, yku70 mutation increased DSB-induced HR between direct repeats by 1.3-fold in a haploid strain and by 1.5-fold in a MAT homozygous (a/a) diploid, but yku70 had no effect on HR in a MAT heterozygous (a/α) diploid. yku70 might increase HR because it eliminates the competing precise NHEJ (religation) pathway and/or because yKu70p interferes directly or indirectly with HR. Despite the yku70-dependent increase in a/a cells, HR remained 2-fold lower than in a/α cells. Cell survival was also lower in a/a cells and correlated with the reduction in HR. These results indicate that MAT heterozygosity enhances DSB-induced HR by yKu-dependent and -independent mechanisms, with the latter mechanism promoting cell survival. Surprisingly, yku70 strains survived a DSB slightly better than wild type. We propose that this reflects enhanced HR, not by elimination of precise NHEJ since this pathway produces viable products, but by elimination of yKu-dependent interference of HR. |
| Databáze: | OpenAIRE |
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