(CA/TG) Microsatellite Sequences Escape the Inhibition of Recombination by Mismatch Repair in Saccharomyces cerevisiae

Abstract Sequence divergence reduces the frequency of recombination, a process that is dependent on the activity of the mismatch repair system. In the yeast Saccharomyces cerevisiae, repair of mismatches results in gene conversion or restoration, whereas failure to repair mismatches results in postmeiotic segregation (PMS). By examining the conversion and PMS in yeast strains deficient in various MMR genes and heterozygous for large inserts (107 bp) with either a mixed sequence or a 39 (CA/TG) repetitive microsatellite sequence, we demonstrate that: (1) the inhibition of conversion by large inserts depends upon a complex containing both Msh2 and Pms1 proteins; (2) conversion is not inhibited if the single-stranded DNA loop in the heteroduplex is the microsatellite sequence; and (3) large heteroduplex loops with random sequence or repetitive sequence might be repaired by two complexes, containing either Msh2 or Pms1. Our results suggest that inhibition of recombination by heterologous inserts and large loop repair are not processed by the same MMR complexes. We propose that the inhibition of conversion by large inserts is due to recognition by the Msh2/Pms1 complex of mismatches created by intrastrand interactions in the heteroduplex loop.

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The influence of the mismatch-repair system on stationary-phase mutagenesis in the yeast Saccharomyces cerevisiae

Current Genetics ◽

10.1007/s00294-002-0334-7 ◽

2002 ◽

Vol 42 (3) ◽

pp. 140-146 ◽

Cited By ~ 27

Author(s):

Agnieszka Hałas ◽

Hanna Baranowska ◽

Zofia Policińska

Keyword(s):

Saccharomyces Cerevisiae ◽

Stationary Phase ◽

Mismatch Repair ◽

Repair System ◽

Yeast Saccharomyces Cerevisiae ◽

Mismatch Repair System

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Poorly Repaired Mismatches in Heteroduplex DNA are Hyper-Recombinagenic in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/142.2.407 ◽

1996 ◽

Vol 142 (2) ◽

pp. 407-416 ◽

Cited By ~ 3

Author(s):

P Manivasakam ◽

Susan M Rosenberg ◽

P J Hastings

Keyword(s):

Saccharomyces Cerevisiae ◽

Mismatch Repair ◽

Genetic Markers ◽

Meiotic Recombination ◽

Repair System ◽

Normal Allele ◽

Heteroduplex Dna ◽

Mismatch Repair System ◽

Postmeiotic Segregation ◽

System Operating

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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The mismatch repair system reduces meiotic homeologous recombination and stimulates recombination-dependent chromosome loss.

Molecular and Cellular Biology ◽

10.1128/mcb.16.11.6110 ◽

1996 ◽

Vol 16 (11) ◽

pp. 6110-6120 ◽

Cited By ~ 125

Author(s):

S R Chambers ◽

N Hunter ◽

E J Louis ◽

R H Borts

Keyword(s):

Mismatch Repair ◽

Genetic Recombination ◽

Sequence Divergence ◽

Chromosome Loss ◽

Repair System ◽

Closely Related Species ◽

Spore Viability ◽

Mismatch Repair System ◽

Homeologous Recombination ◽

Chromosome Iii

Efficient genetic recombination requires near-perfect homology between participating molecules. Sequence divergence reduces the frequency of recombination, a process that is dependent on the activity of the mismatch repair system. The effects of chromosomal divergence in diploids of Saccharomyces cerevisiae in which one copy of chromosome III is derived from a closely related species, Saccharomyces paradoxus, have been examined. Meiotic recombination between the diverged chromosomes is decreased by 25-fold. Spore viability is reduced with an observable increase in the number of tetrads with only two or three viable spores. Asci with only two viable spores are disomic for chromosome III, consistent with meiosis I nondisjunction of the homeologs. Asci with three viable spores are highly enriched for recombinants relative to tetrads with four viable spores. In 96% of the class with three viable spores, only one spore possesses a recombinant chromosome III, suggesting that the recombination process itself contributes to meiotic death. This phenomenon is dependent on the activities of the mismatch repair genes PMS1 and MSH2. A model of mismatch-stimulated chromosome loss is proposed to account for this observation. As expected, crossing over is increased in pms1 and msh2 mutants. Furthermore, genetic exchange in pms1 msh2 double mutants is affected to a greater extent than in either mutant alone, suggesting that the two proteins act independently to inhibit homeologous recombination. All mismatch repair-deficient strains exhibited reductions in the rate of chromosome III nondisjunction.

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Barriers to Genetic Exchange between Bacterial Species: Streptococcus pneumoniae Transformation

Journal of Bacteriology ◽

10.1128/jb.182.4.1016-1023.2000 ◽

2000 ◽

Vol 182 (4) ◽

pp. 1016-1023 ◽

Cited By ~ 143

Author(s):

Jacek Majewski ◽

Piotr Zawadzki ◽

Paul Pickerill ◽

Frederick M. Cohan ◽

Christopher G. Dowson

Keyword(s):

Streptococcus Pneumoniae ◽

Mismatch Repair ◽

Bacterial Species ◽

Sequence Divergence ◽

Sexual Isolation ◽

Genetic Exchange ◽

Repair System ◽

Exponential Relationship ◽

Rapid Acquisition ◽

Mismatch Repair System

ABSTRACT Interspecies genetic exchange is an important evolutionary mechanism in bacteria. It allows rapid acquisition of novel functions by transmission of adaptive genes between related species. However, the frequency of homologous recombination between bacterial species decreases sharply with the extent of DNA sequence divergence between the donor and the recipient. In Bacillus andEscherichia, this sexual isolation has been shown to be an exponential function of sequence divergence. Here we demonstrate that sexual isolation in transformation between Streptococcus pneumoniae recipient strains and donor DNA from related strains and species follows the described exponential relationship. We show that the Hex mismatch repair system poses a significant barrier to recombination over the entire range of sequence divergence (0.6 to 27%) investigated. Although mismatch repair becomes partially saturated, it is responsible for 34% of the observed sexual isolation. This is greater than the role of mismatch repair inBacillus but less than that in Escherichia. The remaining non-Hex-mediated barrier to recombination can be provided by a variety of mechanisms. We discuss the possible additional mechanisms of sexual isolation, in view of earlier findings fromBacillus, Escherichia, andStreptococcus.

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Hypermutability of homonucleotide runs in mismatch repair and DNA polymerase proofreading yeast mutants.

Molecular and Cellular Biology ◽

10.1128/mcb.17.5.2859 ◽

1997 ◽

Vol 17 (5) ◽

pp. 2859-2865 ◽

Cited By ~ 221

Author(s):

H T Tran ◽

J D Keen ◽

M Kricker ◽

M A Resnick ◽

D A Gordenin

Keyword(s):

Mismatch Repair ◽

Dna Polymerase ◽

Repair System ◽

Yeast Saccharomyces Cerevisiae ◽

Genetic Changes ◽

Coding Sequences ◽

Frameshift Mutations ◽

Dna Polymerase Epsilon ◽

Mismatch Repair System ◽

Repair Defect

Homonucleotide runs in coding sequences are hot spots for frameshift mutations and potential sources of genetic changes leading to cancer in humans having a mismatch repair defect. We examined frameshift mutations in homonucleotide runs of deoxyadenosines ranging from 4 to 14 bases at the same position in the LYS2 gene of the yeast Saccharomyces cerevisiae. In the msh2 mismatch repair mutant, runs of 9 to 14 deoxyadenosines are 1,700-fold to 51,000-fold, respectively, more mutable for single-nucleotide deletions than are runs of 4 deoxyadenosines. These frameshift mutations can account for up to 99% of all forward mutations inactivating the 4-kb LYS2 gene. Based on results with single and double mutations of the POL2 and MSH2 genes, both DNA polymerase epsilon proofreading and mismatch repair are efficient for short runs while only the mismatch repair system prevents frameshift mutations in runs of > or = 8 nucleotides. Therefore, coding sequences containing long homonucleotide runs are likely to be at risk for mutational inactivation in cells lacking mismatch repair capability.

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Functional Specifics of the MutL Protein of the DNA Mismatch Repair System in Different Organisms

Russian Journal of Bioorganic Chemistry ◽

10.1134/s1068162020060217 ◽

2020 ◽

Vol 46 (6) ◽

pp. 875-890

Author(s):

M. V. Monakhova ◽

M. A. Milakina ◽

R. M. Trikin ◽

T. S. Oretskaya ◽

E. A. Kubareva

Keyword(s):

Mismatch Repair ◽

Dna Mismatch Repair ◽

Repair System ◽

Dna Mismatch ◽

Dna Mismatch Repair System ◽

Mismatch Repair System

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Saturation of DNA Mismatch Repair and Error Catastrophe by a Base Analogue in Escherichia coli

Genetics ◽

10.1093/genetics/161.4.1363 ◽

2002 ◽

Vol 161 (4) ◽

pp. 1363-1371

Author(s):

Kazuo Negishi ◽

David Loakes ◽

Roel M Schaaper

Keyword(s):

Escherichia Coli ◽

Mismatch Repair ◽

Dna Mismatch Repair ◽

Repair System ◽

Mutagenic Action ◽

Wild Type ◽

Dna Mismatch ◽

Cell Counts ◽

Error Catastrophe ◽

Mismatch Repair System

Abstract Deoxyribosyl-dihydropyrimido[4,5-c][1,2]oxazin-7-one (dP) is a potent mutagenic deoxycytidine-derived base analogue capable of pairing with both A and G, thereby causing G · C → A · T and A · T → G · C transition mutations. We have found that the Escherichia coli DNA mismatch-repair system can protect cells against this mutagenic action. At a low dose, dP is much more mutagenic in mismatch-repair-defective mutH, mutL, and mutS strains than in a wild-type strain. At higher doses, the difference between the wild-type and the mutator strains becomes small, indicative of saturation of mismatch repair. Introduction of a plasmid containing the E. coli mutL+ gene significantly reduces dP-induced mutagenesis. Together, the results indicate that the mismatch-repair system can remove dP-induced replication errors, but that its capacity to remove dP-containing mismatches can readily be saturated. When cells are cultured at high dP concentration, mutant frequencies reach exceptionally high levels and viable cell counts are reduced. The observations are consistent with a hypothesis in which dP-induced cell killing and growth impairment result from excess mutations (error catastrophe), as previously observed spontaneously in proofreading-deficient mutD (dnaQ) strains.

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Antagonism of Ultraviolet-Light Mutagenesis by the Methyl-Directed Mismatch-Repair System of Escherichia coli

Genetics ◽

10.1093/genetics/154.2.503 ◽

2000 ◽

Vol 154 (2) ◽

pp. 503-512 ◽

Cited By ~ 1

Author(s):

Hongbo Liu ◽

Stephen R Hewitt ◽

John B Hays

Keyword(s):

Escherichia Coli ◽

Mismatch Repair ◽

Excision Repair ◽

Spontaneous Mutation ◽

Repair System ◽

Uv Mutagenesis ◽

Repair Protein ◽

Mismatch Repair System

Abstract Previous studies have demonstrated that the Escherichia coli MutHLS mismatch-repair system can process UV-irradiated DNA in vivo and that the human MSH2·MSH6 mismatch-repair protein binds more strongly in vitro to photoproduct/base mismatches than to “matched” photoproducts in DNA. We tested the hypothesis that mismatch repair directed against incorrect bases opposite photoproducts might reduce UV mutagenesis, using two alleles at E. coli lacZ codon 461, which revert, respectively, via CCC → CTC and CTT → CTC transitions. F′ lacZ targets were mated from mut+ donors into mutH, mutL, or mutS recipients, once cells were at substantial densities, to minimize spontaneous mutation prior to irradiation. In umu+ mut+ recipients, a range of UV fluences induced lac+ revertant frequencies of 4–25 × 10−8; these frequencies were consistently 2-fold higher in mutH, mutL, or mutS recipients. Since this effect on mutation frequency was unaltered by an Mfd− defect, it appears not to involve transcription-coupled excision repair. In mut+ umuC122::Tn5 bacteria, UV mutagenesis (at 60 J/m2) was very low, but mutH or mutL or mutS mutations increased reversion of both lacZ alleles roughly 25-fold, to 5–10 × 10−8. Thus, at UV doses too low to induce SOS functions, such as Umu2′D, most incorrect bases opposite occasional photoproducts may be removed by mismatch repair, whereas in heavily irradiated (SOS-induced) cells, mismatch repair may only correct some photoproduct/base mismatches, so UV mutagenesis remains substantial.

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