scholarly journals Recombination of Ty elements in yeast can be induced by a double-strand break.

Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 67-77 ◽  
Author(s):  
A Parket ◽  
O Inbar ◽  
M Kupiec
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Strand Break ◽  
Double Strand Break ◽  
The Other ◽  
Direct Repeats ◽  
Yeast Saccharomyces Cerevisiae ◽  
Low Frequencies ◽  
Ty Elements ◽  
Main Family

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.

scholarly journals DMC1 Functions in a Saccharomyces cerevisiae Meiotic Pathway That Is Largely Independent of the RAD51 Pathway

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 533-544 ◽  
Author(s):  
Michael E Dresser ◽  
Debra J Ewing ◽  
Michael N Conrad ◽  
Ana M Dominguez ◽  
Robert Barstead ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fusion Proteins ◽  
Strand Break ◽  
Double Strand Break ◽  
Yeast Saccharomyces Cerevisiae ◽  
Atp Binding Site ◽  
Epistasis Analysis ◽  
Dna Double Strand Break ◽  
Chromosome Fragments ◽  
Two Hybrid

Meiotic recombinationin the yeast Saccharomyces cerevisiae requires two similar recA-like proteins, Dmc1p and Rad51p. A screen for dominant meiotic mutants provided DMC1-G126D, a dominant allele mutated in the conserved ATP-binding site (specifically, the A-loop motif) that confers a null phenotype. A recessive null allele, dmc1-K69E, was isolated as an intragenic suppressor of DMC1-G126D. Dmc1-K69Ep, unlike Dmc1p, does not interact homotypically in a two-hybrid assay, although it does interact with other fusion proteins identified by two-hybrid screen with Dmc1p. Dmc1p, unlike Rad51p, does not interact in the two-hybrid assay with Rad52p or Rad54p. However, Dmc1p does interact with Tid1p, a Rad54p homologue, with Tid4p, a Rad16p homologue, and with other fusion proteins that do not interact with Rad51p, suggesting that Dmc1p and Rad51p function in separate, though possibly overlapping, recombinational repair complexes. Epistasis analysis suggests that DMC1 and RAD51 function in separate pathways responsible for meiotic recombination. Taken together, our results are consistent with a requirement for DMC1 for meiosis-specific entry of DNA double-strand break ends into chromatin. Interestingly, the pattern on CHEF gels of chromosome fragments that result from meiotic DNA double-strand break formation is different in DMC1 mutant strains from that seen in rad50S strains.

scholarly journals Mitotic gene conversion tracts associated with repair of a defined double-strand break in Saccharomyces cerevisiae

2017 ◽  
Author(s):  
Yee Fang Hum ◽  
Sue Jinks-Robertson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Homologous Recombination ◽  
Gene Conversion ◽  
Strand Break ◽  
Double Strand Break ◽  
The Other ◽  
Homologous Chromosomes ◽  
Molecular Features ◽  
Single Side ◽  
Mitotic Gene Conversion

AbstractMitotic recombination between homologous chromosomes can lead to loss-of-heterozygosity (LOH), which is an important contributor to human disease. In the current study, a defined double-strand break (DSB) on chromosome IV was used to initiate LOH in a yeast strain with sequence-diverged chromosomes. Associated gene conversion tracts, which reflect the repair of mismatches formed when diverged chromosomes exchange single strands, were mapped using microarrays. LOH events reflected two broken chromosomes, one of which was repaired as a crossover and the other as a noncrossover. Gene conversion tracts associated with individual crossover and noncrossover events were similar in size and position, with half of the tracts unexpectedly mapping to only a single side of the initiating break. Although the molecular features of DSB-initiated events generally agree with those predicted by current models of homologous recombination, there were unexpected complexities in associated gene conversion tracts.

scholarly journals A 140-bp-Long Palindromic Sequence Induces Double-Strand Breaks During Meiosis in the Yeast Saccharomyces cerevisiae

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 835-847 ◽  
Author(s):  
Dilip K Nag ◽  
Alicia Kurst
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mismatch Repair ◽  
Meiotic Recombination ◽  
Strand Break ◽  
Double Strand Break ◽  
Hairpin Structure ◽  
Palindromic Sequence ◽  
Yeast Saccharomyces Cerevisiae ◽  
Short Hairpin ◽  
Palindromic Sequences

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.

scholarly journals Patterns of Heteroduplex Formation Associated With the Initiation of Meiotic Recombination in the Yeast Saccharomyces cerevisiae

Genetics ◽  
2003 ◽  
Vol 165 (1) ◽  
pp. 47-63 ◽  
Author(s):  
Jason D Merker ◽  
Margaret Dominska ◽  
Thomas D Petes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Strand Break ◽  
Double Strand Break ◽  
Mechanism Synthesis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Double Stranded Dna ◽  
Strand Annealing ◽  
Break Induced Replication ◽  
Heteroduplex Formation

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.

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