scholarly journals Crossover Interference in Saccharomyces cerevisiae Requires a TID1/RDH54- and DMC1-Dependent Pathway

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1273-1286 ◽  
Author(s):  
Miki Shinohara ◽  
Kazuko Sakai ◽  
Akira Shinohara ◽  
Douglas K Bishop

Abstract Two RecA-like recombinases, Rad51 and Dmc1, function together during double-strand break (DSB)-mediated meiotic recombination to promote homologous strand invasion in the budding yeast Saccharomyces cerevisiae. Two partially redundant proteins, Rad54 and Tid1/Rdh54, act as recombinase accessory factors. Here, tetrad analysis shows that mutants lacking Tid1 form four-viable-spore tetrads with levels of interhomolog crossover (CO) and noncrossover recombination similar to, or slightly greater than, those in wild type. Importantly, tid1 mutants show a marked defect in crossover interference, a mechanism that distributes crossover events nonrandomly along chromosomes during meiosis. Previous work showed that dmc1Δ mutants are strongly defective in strand invasion and meiotic progression and that these defects can be partially suppressed by increasing the copy number of RAD54. Tetrad analysis is used to show that meiotic recombination in RAD54-suppressed dmc1Δ cells is similar to that in tid1; the frequency of COs and gene conversions is near normal, but crossover interference is defective. These results support the proposal that crossover interference acts at the strand invasion stage of recombination.

Genetics ◽  
1993 ◽  
Vol 134 (1) ◽  
pp. 5-19 ◽  
Author(s):  
S E Porter ◽  
M A White ◽  
T D Petes

Abstract In the yeast Saccharomyces cerevisiae, the binding of the Rap1 protein to a site located between the 5' end of the HIS4 gene and the 3' end of BIK1 stimulates meiotic recombination at both flanking loci. By using strains that contain mutations located in HIS4 and BIK1, we found that most recombination events stimulated by the binding of Rap1 involve HIS4 or BIK1, rather than bidirectional events including both loci. The patterns of aberrant segregation indicate that most of the Rap1-stimulated recombination events do not represent the symmetric processing of a double-strand DNA break located at the Rap1-binding site.


Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 835-847 ◽  
Author(s):  
Dilip K Nag ◽  
Alicia Kurst

Palindromic sequences have the potential to form hairpin or cruciform structures, which are putative substrates for several nucleases and mismatch repair enzymes. A genetic method was developed to detect such structures in vivo in the yeast Saccharomyces cerevisiae. Using this method we previously showed that short hairpin structures are poorly repaired by the mismatch repair system in S. cerevisiae. We show here that mismatches, when present in the stem of the hairpin structure, are not processed by the repair machinery, suggesting that they are treated differently than those in the interstrand base-paired duplex DNA. A 140-bp-long palindromic sequence, on the contrary, acts as a meiotic recombination hotspot by generating a site for a double-strand break, an initiator of meiotic recombination. We suggest that long palindromic sequences undergo cruciform extrusion more readily than short ones. This cruciform structure then acts as a substrate for structure-specific nucleases resulting in the formation of a double-strand break during meiosis in yeast. In addition, we show that residual repair of the short hairpin structure occurs in an MSH2-independent pathway.


Genetics ◽  
2003 ◽  
Vol 165 (1) ◽  
pp. 47-63 ◽  
Author(s):  
Jason D Merker ◽  
Margaret Dominska ◽  
Thomas D Petes

Abstract The double-strand break repair (DSBR) model of recombination predicts that heteroduplexes will be formed in regions that flank the double-strand break (DSB) site and that the resulting intermediate is resolved to generate either crossovers or noncrossovers for flanking markers. Previous studies in Saccharomyces cerevisiae, however, failed to detect heteroduplexes on both sides of the DSB site. Recent physical studies suggest that some recombination events involve heterodupex formation by a mechanism, synthesis-dependent strand annealing (SDSA), that is inherently asymmetric with respect to the DSB site and that leads exclusively to noncrossovers of flanking markers. Below, we demonstrate that many of the recombination events initiated at the HIS4 recombination hotspot are consistent with a variant of the DSBR model in which the extent of heteroduplex on one side of the DSB site is much greater than that on the other. Events that include only one flanking marker in the heteroduplex (unidirectional events) are usually resolved as noncrossovers, whereas events that include both flanking markers (bidirectional events) are usually resolved as crossovers. The unidirectional events may represent SDSA, consistent with the conclusions of others, although other possibilities are not excluded. We also show that the level of recombination reflects the integration of events initiated at several different DSB sites, and we identify a subset of gene conversion events that may involve break-induced replication (BIR) or repair of a double-stranded DNA gap.


Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 67-77 ◽  
Author(s):  
A Parket ◽  
O Inbar ◽  
M Kupiec

Abstract The Ty retrotransposons are the main family of dispersed repeated sequences in the yeast Saccharomyces cerevisiae. These elements are flanked by a pair of long terminal direct repeats (LTRs). Previous experiments have shown that Ty elements recombine at low frequencies, despite the fact that they are present in 30 copies per genome. This frequency is not highly increased by treatments that cause DNA damage, such as UV irradiation. In this study, we show that it is possible to increase the recombination level of a genetically marked Ty by creating a double-strand break in it. This break is repaired by two competing mechanisms: one of them leaves a single LTR in place of the Ty, and the other is a gene conversion event in which the marked Ty is replaced by an ectopically located one. In a strain in which the marked Ty has only one LTR, the double-strand break is repaired by conversion. We have also measured the efficiency of repair and monitored the progression of the cells through the cell-cycle. We found that in the presence of a double-strand break in the marked Ty, a proportion of the cells is unable to resume growth.


Genetics ◽  
1997 ◽  
Vol 145 (3) ◽  
pp. 661-670 ◽  
Author(s):  
Qing-Qing Fan ◽  
Fei Xu ◽  
Michael A White ◽  
Thomas D Petes

In a wild-type strain of Saccharomyces cerevisiae, a hotspot for meiotic recombination is located upstream of the HIS4 gene. An insertion of a 49-bp telomeric sequence into the coding region of HIS4 strongly stimulates meiotic recombination and the local formation of meiosis-specific double-strand DNA breaks (DSBs). When strains are constructed in which both hotspots are heterozygous, hotspot activity is substantially less when the hotspots are on the same chromosome than when they are on opposite chromosomes.


1990 ◽  
Vol 10 (5) ◽  
pp. 2104-2110
Author(s):  
A P Mitchell ◽  
S E Driscoll ◽  
H E Smith

In the yeast Saccharomyces cerevisiae, meiosis and spore formation require the induction of sporulation-specific genes. Two genes are thought to activate the sporulation program: IME1 and IME2 (inducer of meiosis). Both genes are induced upon entry into meiosis, and IME1 is required for IME2 expression. We report here that IME1 is essential for expression of four sporulation-specific genes. In contrast, IME2 is not absolutely essential for expression of the sporulation-specific genes, but contributes to their rapid induction. Expression of IME2 from a heterologous promoter permits the expression of these sporulation-specific genes, meiotic recombination, and spore formation in the absence of IME1. We propose that the IME1 and IME2 products can each activate sporulation-specific genes independently. In addition, the IME1 product stimulates sporulation-specific gene expression indirectly through activation of IME2 expression.


Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1363-1373 ◽  
Author(s):  
Rachel B Tennyson ◽  
Nathalie Ebran ◽  
Anissa E Herrera ◽  
Janet E Lindsley

Abstract Chromosomal translocations are common genetic abnormalities found in both leukemias and solid tumors. While much has been learned about the effects of specific translocations on cell proliferation, much less is known about what causes these chromosome rearrangements. This article describes the development and use of a system that genetically selects for rare translocation events using the yeast Saccharomyces cerevisiae. A translocation YAC was created that contains the breakpoint cluster region from the human MLL gene, a gene frequently involved in translocations in leukemia patients, flanked by positive and negative selection markers. A translocation between the YAC and a yeast chromosome, whose breakpoint falls within the MLL DNA, physically separates the markers and forms the basis for the selection. When RAD52 is deleted, essentially all of the selected and screened cells contain simple translocations. The detectable translocation rates are the same in haploids and diploids, although the mechanisms involved and true translocation rates may be distinct. A unique double-strand break induced within the MLL sequences increases the number of detectable translocation events 100- to 1000-fold. This novel system provides a tractable assay for answering basic mechanistic questions about the development of chromosomal translocations.


1993 ◽  
Vol 13 (4) ◽  
pp. 2324-2331 ◽  
Author(s):  
D K Nag ◽  
T D Petes

We describe a general physical method for detecting the heteroduplex DNA that is formed as an intermediate in meiotic recombination in the yeast Saccharomyces cerevisiae. We use this method to study the kinetic relationship between the formation of heteroduplex DNA and other meiotic events. We show that strains with the rad50, but not the rad52, mutation are defective in heteroduplex formation. We also demonstrate that, although cruciform structures can be formed in vivo as a consequence of heteroduplex formation between DNA strands that contain different palindromic insertions, small palindromic sequences in homoduplex DNA are rarely extruded into the cruciform conformation.


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