Dissociation of Rad51 Presynaptic Complexes and Heteroduplex DNA Joints by Tandem Assemblies of Srs2

Abstract In yeast meiotic recombination, alleles used as genetic markers fall into two classes as regards their fate when incorporated into heteroduplex DNA. Normal alleles are those that form heteroduplexes that are nearly always recognized and corrected by the mismatch repair system operating in meiosis. High PMS (postmeiotic segregation) alleles form heteroduplexes that are inefficiently mismatch repaired. We report that placing any of several high PMS alleles very close to normal alleles causes hyperrecombination between these markers. We propose that this hyperrecombination is caused by the high PMS allele blocking a mismatch repair tract initiated from the normal allele, thus preventing corepair of the two alleles, which would prevent formation of recombinants. The results of three point crosses involving two PMS alleles and a normal allele suggest that high PMS alleles placed between two alleles that are normally corepaired block that corepair.

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Processing of mispaired and unpaired bases in heteroduplex DNA in E. coli()

Biochimie ◽

10.1016/s0300-9084(85)80162-0 ◽

1985 ◽

Vol 67 (7-8) ◽

pp. 745-752 ◽

Cited By ~ 3

Author(s):

M RADMAN ◽

C DOHET ◽

M JONES ◽

M DOUTRIAUX ◽

F LAENGLEROUAULT ◽

...

Keyword(s):

Heteroduplex Dna ◽

E Coli

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Nonrandom transition from asymmetrical to symmetrical hybrid DNA during meiotic recombination

Genome ◽

10.1139/g89-464 ◽

1989 ◽

Vol 32 (3) ◽

pp. 414-419 ◽

Cited By ~ 2

Author(s):

Angelos Kalogeropoulos ◽

Jean-Luc Rossignol

Keyword(s):

Meiotic Recombination ◽

Heteroduplex Dna ◽

Dna Distribution ◽

Left Part ◽

Ascobolus Immersus ◽

Two Phases ◽

The Right ◽

Hybrid Dna

During meiotic recombination, in the b2 gene of Ascobolus immersus hybrid DNA can be formed either on only one (asymmetrical hybrid DNA) or on both (symmetrical hybrid DNA) interacting chromatids. The two phases can be found in the same meiosis, involving the same two interacting chromatids with the symmetrical phase located on the right with regard to the asymmetrical one. We show that the transition from the asymmetrical to the symmetrical phase occurs in a defined region located within the left part of the gene, which is closer to the initiation region. Once formed, the symmetrical hybrid DNA phase seems always to extend to the rightmost mutation sites. This contrasts with asymmetrical hybrid DNA extension, which when it stays in asymmetrical form, may stop within the gene.Key words: Ascobolus immersus, heteroduplex DNA distribution.

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A Test of the Double-Strand Break Repair Model for Meiotic Recombination in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/144.1.27 ◽

1996 ◽

Vol 144 (1) ◽

pp. 27-41 ◽

Cited By ~ 7

Author(s):

Larry A Gilbertson ◽

Franklin W Stahl

Keyword(s):

Meiotic Recombination ◽

Strand Break ◽

Double Strand Break ◽

Double Strand Break Repair ◽

Holliday Junction ◽

Single Event ◽

Heteroduplex Dna ◽

Holliday Junction Resolvase ◽

Break Repair ◽

Two Sides

Abstract We tested predictions of the double-strand break repair (DSBR) model for meiotic recombination by examining the segregation patterns of small palindromic insertions, which frequently escape mismatch repair when in heteroduplex DNA. The palindromes flanked a well characterized DSB site at the ARC4 locus. The “canonical” DSBR model, in which only 5′ ends are degraded and resolution of the four-stranded intermediate is by Holliday junction resolvase, predicts that hDNA will frequently occur on both participating chromatids in a single event. Tetrads reflecting this configuration of hDNA were rare. In addition, a class of tetrads not predicted by the canonical DSBR model was identified. This class represented events that produced hDNA in a “trans” configuration, on opposite strands of the same duplex on the two sides of the DSB site. Whereas most classes of convertant tetrads had typical frequencies of associated crossovers, tetrads with trans hDNA were parental for flanking markers. Modified versions of the DSBR model, including one that uses a topoisomerase to resolve the canonical DSBR intermediate, are supported by these data.

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Induction of recombination between homologous and diverged DNAs by double-strand gaps and breaks and role of mismatch repair

Molecular and Cellular Biology ◽

10.1128/mcb.14.7.4802-4814.1994 ◽

1994 ◽

Vol 14 (7) ◽

pp. 4802-4814

Author(s):

S D Priebe ◽

J Westmoreland ◽

T Nilsson-Tillgren ◽

M A Resnick

Keyword(s):

Gene Conversion ◽

Mismatch Repair ◽

Sequence Divergence ◽

Strand Break ◽

Mismatch Repair Gene ◽

Repair Gene ◽

Heteroduplex Dna ◽

Dna Mismatch ◽

Spontaneous Recombination ◽

The Impact

Sequence homology is expected to influence recombination. To further understand mechanisms of recombination and the impact of reduced homology, we examined recombination during transformation between plasmid-borne DNA flanking a double-strand break (DSB) or gap and its chromosomal homolog. Previous reports have concentrated on spontaneous recombination or initiation by undefined lesions. Sequence divergence of approximately 16% reduced transformation frequencies by at least 10-fold. Gene conversion patterns associated with double-strand gap repair of episomal plasmids or with plasmid integration were analyzed by restriction endonuclease mapping and DNA sequencing. For episomal plasmids carrying homeologous DNA, at least one input end was always preserved beyond 10 bp, whereas for plasmids carrying homologous DNA, both input ends were converted beyond 80 bp in 60% of the transformants. The system allowed the recovery of transformants carrying mixtures of recombinant molecules that might arise if heteroduplex DNA--a presumed recombination intermediate--escapes mismatch repair. Gene conversion involving homologous DNAs frequently involved DNA mismatch repair, directed to a broken strand. A mutation in the PMS1 mismatch repair gene significantly increased the fraction of transformants carrying a mixture of plasmids for homologous DNAs, indicating that PMS1 can participate in DSB-initiated recombination. Since nearly all transformants involving homeologous DNAs carried a single recombinant plasmid in both Pms+ and Pms- strains, stable heteroduplex DNA appears less likely than for homologous DNAs. Regardless of homology, gene conversion does not appear to occur by nucleolytic expansion of a DSB to a gap prior to recombination. The results with homeologous DNAs are consistent with a recombinational repair model that we propose does not require the formation of stable heteroduplex DNA but instead involves other homology-dependent interactions that allow recombination-dependent DNA synthesis.

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Mismatch repair of heteroduplex DNA intermediates of extrachromosomal recombination in mammalian cells

Molecular and Cellular Biology ◽

10.1128/mcb.14.1.400-406.1994 ◽

1994 ◽

Vol 14 (1) ◽

pp. 400-406

Author(s):

W P Deng ◽

J A Nickoloff

Keyword(s):

Dna Replication ◽

Mismatch Repair ◽

Mammalian Cells ◽

Strand Break ◽

Wild Type ◽

Heteroduplex Dna ◽

Frameshift Mutations ◽

Single Strand Annealing ◽

Extrachromosomal Recombination ◽

Strand Annealing

Previous work indicated that extrachromosomal recombination in mammalian cells could be explained by the single-strand annealing (SSA) model. This model predicts that extrachromosomal recombination leads to nonconservative crossover products and that heteroduplex DNA (hDNA) is formed by annealing of complementary single strands. Mismatched bases in hDNA may subsequently be repaired to wild-type or mutant sequences, or they may remain unrepaired and segregate following DNA replication. We describe a system to examine the formation and mismatch repair of hDNA in recombination intermediates. Our results are consistent with extrachromosomal recombination occurring via SSA and producing crossover recombinant products. As predicted by the SSA model, hDNA was present in double-strand break-induced recombination intermediates. By placing either silent or frameshift mutations in the predicted hDNA region, we have shown that mismatches are efficiently repaired prior to DNA replication.

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MutS binding protects heteroduplex DNA from exonuclease digestionin vitro: a simple method for detecting mutations

Nucleic Acids Research ◽

10.1093/nar/22.13.2710 ◽

1994 ◽

Vol 22 (13) ◽

pp. 2710-2711 ◽

Cited By ~ 35

Author(s):

L.A. Ellis ◽

G.R. Taylor ◽

R. Banks ◽

S. Baumberg

Keyword(s):

Simple Method ◽

Heteroduplex Dna

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High-resolution mapping of heteroduplex DNA formed during UV-induced and spontaneous mitotic recombination events in yeast

10.1101/131995 ◽

2017 ◽

Author(s):

Yi Yin ◽

Margaret Dominska ◽

Eunice Yim ◽

Thomas D. Petes

Keyword(s):

Type Strain ◽

Wild Type Strain ◽

Mitotic Recombination ◽

Template Switching ◽

Wild Type ◽

Dna Breaks ◽

Repair Synthesis ◽

Heteroduplex Dna ◽

Dna Molecule ◽

Double Stranded Dna

AbstractDouble-stranded DNA breaks (DSBs) can be generated by both endogenous and exogenous agents. In diploid yeast strains, such breaks are usually repaired by homologous recombination (HR), and a number of different HR pathways have been described. An early step for all HR pathways is formation of a heteroduplex, in which a single-strand from the broken DNA molecule pairs with a strand derived from an intact DNA molecule. If the two strands of DNA are not identical, within the heteroduplex DNA (hetDNA), there will be mismatches. In a wild-type strain, these mismatches are removed by the mismatch repair (MMR) system. In strains lacking MMR, the mismatches persist and can be detected by a variety of genetic and physical techniques. Most previous studies involving hetDNA formed during mitotic recombination have been restricted to a single locus with DSBs induced at a defined position by a site-specific endonuclease. In addition, in most of these studies, recombination between repeated genes was examined; in such studies, the sequence homologies were usually less than 5 kb. In the present study, we present a global mapping of hetDNA formed in a UV-treated MMR-defective mlh1 strain. Although about two-thirds of the recombination events were associated with hetDNA with a continuous array of unrepaired mismatches, in about one-third of the events, we found regions of unrepaired mismatches flanking regions without mismatches. We suggest that these discontinuous hetDNAs involve template switching during repair synthesis, repair of a double-stranded DNA gap, and/or Mlh1-independent MMR. Many of our observed events are not explicable by the simplest form of the double-strand break repair (DSBR) model of recombination. We also studied hetDNA associated with spontaneous recombination events selected on chromosomes IV and V in a wild-type strain. The interval on chromosome IV contained a hotspot for spontaneous crossovers generated by an inverted pair of transposable elements (HS4). We showed that HS4-induced recombination events are associated with the formation of very large (>30 kb) double-stranded DNA gaps.

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Effects of DNA heterologies on bacteriophage lambda recombination.

Genetics ◽

10.1093/genetics/118.1.13 ◽

1988 ◽

Vol 118 (1) ◽

pp. 13-19

Author(s):

R K Pearson ◽

M S Fox

Keyword(s):

Bacteriophage Lambda ◽

Indirect Evidence ◽

Direct Products ◽

Base Pairs ◽

Heteroduplex Dna ◽

Deletion Mutations ◽

Genetic Crosses ◽

Insertion And Deletion ◽

Progeny Phage ◽

Substitution Mutation

Abstract Previous studies of bacteriophage lambda recombination have provided indirect evidence that substantial sequence nonhomologies, such as insertions and deletions, may be included in regions of heteroduplex DNA. However, the direct products of heterology-containing heteroduplex DNA--heterozygous progeny phage--have not been observed. We have constructed a series of small insertion and deletion mutations in the cI gene to examine the possibility that small heterologies might be accommodated in heterozygous progeny phage. Genetic crosses were carried out between lambda cI- Oam29 and lambda cI+ Pam80 under replication-restricted conditions. Recombinant O+P+ progeny were selected on mutL hosts and tested for cI heterozygosity. Heterozygous recombinants were readily observed with crosses involving insertions of 4 to 19 base pairs (bp) in the cI gene. Thus, nonhomologies of at least 19 bp can be accommodated in regions of heteroduplex DNA during lambda recombination. In contrast, when a cI insertion or deletion mutation of 26 bp was present, few of the selected recombinants were heterozygous for cI. Results using a substitution mutation, involving a 26-bp deletion with a 22-bp insertion, suggest that the low recovery of cI heterozygotes containing heterologies of 26 bp or more is due to a failure to encapsulate DNA containing heterologies of 26 bp or more into viable phage particles.

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