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.
Bottom Line: 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.Our work reveals that condensin coordinates meiotic recombination with chromosome segregation at the repetitive rDNA sequence, thereby maintaining genome integrity.
Affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370.Show MeSH
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Mentions: We hypothesized that abnormal meiotic recombination in condensin mutants leads to rDNA missegregation. To test this hypothesis, we observed rDNA homologue segregation in spo11Δ and spo11Δ PCLB2-BRN1 mutant cells (Figure 5). In the absence of Spo11, Rad51 focus formation, and therefore meiotic DSBs, was essentially eliminated (Supplemental Figure S2, A–C), and homologues did not form linkages and would segregate randomly (i.e., half the time homologues would segregate to opposite spindle poles, and the other half to the same pole; for a diagram, see Supplemental Figure S2D). This random segregation of homologues was indicated in cells with the GFP marker positioned at three tested loci in both homologues: centromere XII, rDNA, and telomere XII (Figure 5A). Without Spo11, PCLB2-BRN1 cells segregated rDNA homologues at a rate similar to that of the spo11Δ single mutant (Figure 5A), suggesting that rDNA homologue linkage formed in the absence of condensin depends on Spo11.
Affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370.