Variation in Crossover Frequencies Perturb Crossover Assurance Without Affecting Meiotic Chromosome Segregation in <i>Saccharomyces cerevisiae</i>

Krishnaprasad, Gurukripa Nandanan; Mayakonda, Anand; Lin, Gen; Tekkedil, Manu M.; Steinmetz, Lars M.; Nishant, K. T.

doi:10.1534/genetics.114.172320

Cited by 34 publications

(82 citation statements)

References 100 publications

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“…Since most crossovers in mlh3 Δ pch2 Δ are made by the Mus81-Mms4 pathway (Figure 5B), these observations are consistent with noninterfering crossovers being less efficient in supporting an obligate crossover. The higher E0 frequency in mlh3∆ pch2∆ also supports the prediction that S. cerevisiae will require up to 200 crossovers in the absence of genetic interference to have >0.98% probability of an obligate crossover on every homolog pair (Krishnaprasad et al 2015). …”

Section: Discussionsupporting

confidence: 69%

“…Noncrossover counts in mlh3 Δ did not show significant differences on any of the chromosomes compared to wild type (Figure 2B and Figure S2D). The noncrossover data in mlh3∆ are different from msh4 Δ, where average noncrossover counts were increased on several chromosomes (Krishnaprasad et al 2015). When the noncrossover counts are regressed against the crossover counts, we observed no correlation in wild type and mlh3 Δ (wild type, r = 0.23, P = 0.06; mlh3 Δ, r = 0.01, P = 0.95; Figure 2C).…”

Section: Resultsmentioning

confidence: 88%

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Modulating Crossover Frequency and Interference for Obligate Crossovers inSaccharomyces cerevisiaeMeiosis

Chakraborty

Lin

et al. 2017

G3 Genes|Genomes|Genetics

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Meiotic crossover frequencies show wide variation among organisms. But most organisms maintain at least one crossover per homolog pair (obligate crossover). In Saccharomyces cerevisiae, previous studies have shown crossover frequencies are reduced in the mismatch repair related mutant mlh3D and enhanced in a meiotic checkpoint mutant pch2D by up to twofold at specific chromosomal loci, but both mutants maintain high spore viability. We analyzed meiotic recombination events genome-wide in mlh3D, pch2D, and mlh3D pch2D mutants to test the effect of variation in crossover frequency on obligate crossovers. mlh3D showed $30% genome-wide reduction in crossovers (64 crossovers per meiosis) and loss of the obligate crossover, but nonexchange chromosomes were efficiently segregated. pch2D showed $50% genome-wide increase in crossover frequency (137 crossovers per meiosis), elevated noncrossovers as well as loss of chromosome size dependent double-strand break formation. Meiotic defects associated with pch2Δ did not cause significant increase in nonexchange chromosome frequency. Crossovers were restored to wild-type frequency in the double mutant mlh3D pch2D (100 crossovers per meiosis), but obligate crossovers were compromised. Genetic interference was reduced in mlh3D, pch2D, and mlh3D pch2D. Triple mutant analysis of mlh3D pch2D with other resolvase mutants showed that most of the crossovers in mlh3D pch2D are made through the Mus81-Mms4 pathway. These results are consistent with a requirement for increased crossover frequencies in the absence of genetic interference for obligate crossovers. In conclusion, these data suggest crossover frequencies and the strength of genetic interference in an organism are mutually optimized to ensure obligate crossovers. Meiosis is a reductional division that produces haploid gametes or spores from diploid progenitor cells. Ploidy reduction is achieved by one round of DNA replication, followed by two consecutive nuclear divisions (Meiosis I and II), producing four daughter cells (Roeder 1997). Crossovers promote the formation of chiasma which serves as a physical linkage between two homologs and opposes the spindle generated forces that pull apart the homolog pairs. This opposing set of forces provides the tension necessary to promote proper disjunction of homolog pairs at Meiosis I (Petronczki et al. 2003). Failure to maintain at least one crossover per homolog pair increases the probability of nondisjunction, resulting in aneuploid gametes (Serrentino and Borde 2012). Although crossovers are important for chromosome segregation, nonexchange chromosomes have been observed to segregate accurately forming viable gametes (Hawley et al. 1992;Davis and Smith 2003;Kemp et al. 2004;Newnham et al. 2010;Krishnaprasad et al. 2015). Meiotic crossovers (and noncrossovers) are initiated in S. cerevisiae by 150-170 programmed double-strand breaks (DSBs) formed by an evolutionarily conserved topoisomerase-like protein Spo11 and other

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Section: Discussionsupporting

confidence: 69%

Section: Resultsmentioning

confidence: 88%

Modulating Crossover Frequency and Interference for Obligate Crossovers inSaccharomyces cerevisiaeMeiosis

Chakraborty

Lin

et al. 2017

G3 Genes|Genomes|Genetics

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“…Spore viability, 6 indicative of successful meiotic chromosome segregation, was assessed by tetrad dissection and compared to wild-type and msh4∆-null mutant strains (Figure 2A,B). Consistent with previous studies (Krishnaprasad et al, 2015;Nishant et al, 2010;Novak et al, 2001;Stahl et al, 2004), msh4∆ reduced spore viability to 34.7% and the pattern of spore death was indicative of chromosome missegregation at the first meiotic division, with a preponderance of tetrads containing two or zero viable spores (Figure 2B). The pattern of spore death in cells carrying the phosphorylation-defective msh4-6A allele was similar to that of the msh4∆ null, with an overall viability of 46.7% (P<0.01 compared to wild type, χ 2 test; Table S1).…”

Section: Phosphorylation Is Essential For the Crossover Function Of Msh4supporting

confidence: 91%

The crossover function of MutSγ is activated via Cdc7-dependent stabilization of Msh4

Rao

Tang

et al. 2018

Preprint

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The MutSγ complex, Msh4-Msh5, binds DNA joint-molecule (JM) intermediates during homologous recombination to promote crossing over and accurate chromosome segregation at the first division of meiosis. MutSγ facilitates the formation and biased resolution of crossoverspecific JM intermediates called double Holliday junctions. Here we show that these activities are governed by regulated proteasomal degradation. MutSγ is initially inactive for crossing over due to an N-terminal degron on Msh4 that renders it unstable. Activation of MutSγ requires the Dbf4-dependent kinase, Cdc7 (DDK), which directly phosphorylates and thereby neutralizes the Msh4 degron. Phosphorylated Msh4 is chromatin bound and requires DNA strand exchange and chromosome synapsis, implying that DDK specifically targets MutSγ that has already bound nascent JMs. Our study establishes regulated protein degradation as a fundamental mechanism underlying meiotic crossover control. the differentiation of crossover sites manifests as the selective retention and accumulation of specific recombination factors. One such factor is MutSγ, a heterodimer of Msh4 and Msh5, two homologs of the DNA mismatch-recognition factor MutS (Manhart and Alani, 2016;Snowden et al., 2004). Msh4 and Msh5 are members the ZMM proteins (Zip1, Zip2, Zip3, Zip4, Msh4, Msh5, Mer3, and Spo16), a diverse set of activities that facilitate crossover-specific events of recombination, and couple these events to chromosome synapsis (Fung et al., 2004;Hunter, 2015;Lynn et al., 2007;Shinohara et al., 2008). As seen in a variety of species, initial numbers of MutSγ immunostaining foci greatly outnumber final crossover numbers (De Muyt et al., 2014; de Vries et al., 1999;Edelmann et al., 1999;Higgins et al., 2008;Kneitz et al., 2000;Yokoo et al., 2012;Zhang et al., 2014). As prophase I progresses, MutSγ is lost from most recombination sites but retained at sites that will go on to mature into crossovers. This patterning process is dependent on the Zip3/RNF212/ZHP-3/HEI10 family of RING E3 ligases (Agarwal and Roeder, Wang et al., 2012;Yokoo et al., 2012;Zhang et al., 2018). Additional evidence implicates the SUMO-modification and ubiquitin-proteasome systems in meiotic crossover control (Ahuja et al., 2017; Rao et al., 2017) and suggests a model in which factors such as MutSγ are selectively stabilized at crossover sites by protecting them from proteolysis. Implicit in this model is the notion that MutSγ may be intrinsically unstable.Here, we show that regulated proteolysis plays a direct and essential role in meiotic crossing over. Msh4 is identified as an intrinsically unstable protein that is targeted for proteasomal degradation by an N-terminal degron thereby rendering MutSγ inactive for crossing over. Activation of MutSγ occurs by neutralizing the Msh4 degron via Cdc7-catalyzed phosphorylation. Thus, a key meiotic pro-crossover factor is activated by attenuating its proteolysis.

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“…Genome wide recombination mapping of msh2 Δ elucidated barriers mismatch repair poses to recombination as well as new models for recombination 30. Similarly genome wide recombination mapping in mlh2 Δ mutants showed a role for Mlh1‐Mlh2 in regulating the extent of gene conversion tracts 54. Genome wide recombination mapping in msh4 hypomorphs that make fewer crossovers but have normal viability, supported a role for crossover distribution mechanisms in ensuring the obligate crossover 55.…”

Section: New Insights From Genome Wide Analysis Of Meiotic Recombinationmentioning

confidence: 96%

Genome wide analysis of meiotic recombination in yeast: For a few SNPs more

et al. 2018

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Diploid organisms undergo meiosis to produce haploid germ cells. Crossover events during meiosis promote genetic diversity and facilitate accurate chromosome segregation. The baker's yeast Saccharomyces cerevisiae is extensively used as a model for analysis of meiotic recombination. Conventional methods for measuring recombination events in S. cerevisiae have been limited by the number and density of genetic markers. Next generation sequencing (NGS)‐based analysis of hybrid yeast genomes bearing thousands of heterozygous single nucleotide polymorphism (SNP) markers has revolutionized analysis of meiotic recombination. By facilitating analysis of marker segregation in the whole genome with unprecedented resolution, this method has resulted in the generation of high‐resolution recombination maps in wild‐type and meiotic mutants. These studies have provided novel insights into the mechanism of meiotic recombination. In this review, we discuss the methodology, challenges, insights and future prospects of using NGS‐based methods for whole genome analysis of meiotic recombination. The objective is to facilitate the use of these high through‐put sequencing methods for the analysis of meiotic recombination given their power to provide significant new insights into the process. © 2018 The Authors. IUBMB Life published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology, 70(8):743–752, 2018

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Variation in Crossover Frequencies Perturb Crossover Assurance Without Affecting Meiotic Chromosome Segregation in Saccharomyces cerevisiae

Cited by 34 publications

References 100 publications

Modulating Crossover Frequency and Interference for Obligate Crossovers inSaccharomyces cerevisiaeMeiosis

Modulating Crossover Frequency and Interference for Obligate Crossovers inSaccharomyces cerevisiaeMeiosis

The crossover function of MutSγ is activated via Cdc7-dependent stabilization of Msh4

Genome wide analysis of meiotic recombination in yeast: For a few SNPs more

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