Dataset Information

Condensin suppresses recombination and regulates double-strand break processing at the repetitive ribosomal DNA array to ensure proper chromosome segregation during meiosis in budding yeast.

ABSTRACT: During meiosis, homologues are linked by crossover, which is required for bipolar chromosome orientation before chromosome segregation at anaphase I. The repetitive ribosomal DNA (rDNA) array, however, undergoes little or no meiotic recombination. Hyperrecombination can cause chromosome missegregation and rDNA copy number instability. We report here that condensin, a conserved protein complex required for chromosome organization, regulates double-strand break (DSB) formation and repair at the rDNA gene cluster during meiosis in budding yeast. Condensin is highly enriched at the rDNA region during prophase I, released at the prophase I/metaphase I transition, and reassociates with rDNA before anaphase I onset. We show that condensin plays a dual role in maintaining rDNA stability: it suppresses the formation of Spo11-mediated rDNA breaks, and it promotes DSB processing to ensure proper chromosome segregation. Condensin is unnecessary for the export of rDNA breaks outside the nucleolus but required for timely repair of meiotic DSBs. Our work reveals that condensin coordinates meiotic recombination with chromosome segregation at the repetitive rDNA sequence, thereby maintaining genome integrity.

SUBMITTER: Li P

PROVIDER: S-EPMC4230583 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Condensin suppresses recombination and regulates double-strand break processing at the repetitive ribosomal DNA array to ensure proper chromosome segregation during meiosis in budding yeast.

Li Ping P Jin Hui H Yu Hong-Guo HG

Molecular biology of the cell 20140807 19

During meiosis, homologues are linked by crossover, which is required for bipolar chromosome orientation before chromosome segregation at anaphase I. The repetitive ribosomal DNA (rDNA) array, however, undergoes little or no meiotic recombination. Hyperrecombination can cause chromosome missegregation and rDNA copy number instability. We report here that condensin, a conserved protein complex required for chromosome organization, regulates double-strand break (DSB) formation and repair at the rD ...[more]

PMID: 25103240

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Project description:Recombination between homologous chromosomes of different parental origin (homologs) is necessary for their accurate segregation during meiosis. It has been suggested that meiotic inter-homolog recombination is promoted by a barrier to inter-sister-chromatid recombination, imposed by meiosis-specific components of the chromosome axis. Consistent with this, measures of Holliday junction-containing recombination intermediates (joint molecules [JMs]) show a strong bias towards inter-homolog and against inter-sister JMs. However, recombination between sister chromatids also has an important role in meiosis. The genomes of diploid organisms in natural populations are highly polymorphic for insertions and deletions, and meiotic double-strand breaks (DSBs) that form within such polymorphic regions must be repaired by inter-sister recombination. Efforts to study inter-sister recombination during meiosis, in particular to determine recombination frequencies and mechanisms, have been constrained by the inability to monitor the products of inter-sister recombination. We present here molecular-level studies of inter-sister recombination during budding yeast meiosis. We examined events initiated by DSBs in regions that lack corresponding sequences on the homolog, and show that these DSBs are efficiently repaired by inter-sister recombination. This occurs with the same timing as inter-homolog recombination, but with reduced (2- to 3-fold) yields of JMs. Loss of the meiotic-chromosome-axis-associated kinase Mek1 accelerates inter-sister DSB repair and markedly increases inter-sister JM frequencies. Furthermore, inter-sister JMs formed in mek1? mutants are preferentially lost, while inter-homolog JMs are maintained. These findings indicate that inter-sister recombination occurs frequently during budding yeast meiosis, with the possibility that up to one-third of all recombination events occur between sister chromatids. We suggest that a Mek1-dependent reduction in the rate of inter-sister repair, combined with the destabilization of inter-sister JMs, promotes inter-homolog recombination while retaining the capacity for inter-sister recombination when inter-homolog recombination is not possible.

Dataset Information

Condensin suppresses recombination and regulates double-strand break processing at the repetitive ribosomal DNA array to ensure proper chromosome segregation during meiosis in budding yeast.

Publications

Condensin suppresses recombination and regulates double-strand break processing at the repetitive ribosomal DNA array to ensure proper chromosome segregation during meiosis in budding yeast.

Similar Datasets

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