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 showed previously that condensin is enriched at the rDNA array during yeast meiosis (Yu and Koshland, 2003). To determine condensin dynamics, we developed a live-cell fluorescence microscopy method to observe condensin and rDNA movement in yeast cells that were induced to undergo synchronous meiosis (Figure 1). Using green fluorescent protein (GFP)–tagged condensin subunits Brn1 and Ycg1 and a red fluorescent protein (RFP)–marked rDNA array (Li et al., 2011), we found that at the beginning of meiosis (∼5 h before anaphase I onset), Brn1-GFP was highly concentrated at the rDNA gene cluster (Figure 1A). Brn1-GFP became dispersed during prophase I (∼2 h before anaphase I), and its association with rDNA decreased precipitously at late prophase I. Brn1-GFP was undetectable at the rDNA at metaphase I (∼40 min before anaphase I, Shirk et al., 2011), but it reassociated with the rDNA array upon anaphase I onset (Figure 1A). These observations suggest that condensin is subject to relocation inside the yeast nucleus during meiosis.
Affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370.