A Mutation in the Putative MLH3 Endonuclease Domain Confers a Defect in Both Mismatch Repair and Meiosis in<i>Saccharomyces cerevisiae</i>

Nishant, K. T.; Plys, Aaron J.; Alani, Eric

doi:10.1534/genetics.108.086645

Cited by 126 publications

(230 citation statements)

References 51 publications

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“…Mlh1-Pms1 (Mlh1-Pms2 in mammals) functions with both Msh2-Msh6 and Msh2-Msh3, while Mlh1-Mlh3 works primarily with Msh2-Msh3. Pms1 and Mlh3 contain latent endonucleases that cleave the nascent DNA strand, providing entry points for removal of mismatches and error-free DNA resynthesis (Kadyrov et al 2006(Kadyrov et al , 2007Nishant et al 2008).Consistent with these biochemical properties, genetic studies in yeast reveal overlapping mutator phenotypes when individual MMR genes are deleted. Deletion of MSH2 eliminates both Msh6-and Msh3-dependent repair, effectively abrogating MMR and conferring a strong base-substitution and frameshift mutator phenotype.…”

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Emergence of DNA Polymerase ε Antimutators That Escape Error-Induced Extinction in Yeast

2013

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DNA polymerases (Pols) e and d perform the bulk of yeast leading-and lagging-strand DNA synthesis. Both Pols possess intrinsic proofreading exonucleases that edit errors during polymerization. Rare errors that elude proofreading are extended into duplex DNA and excised by the mismatch repair (MMR) system. Strains that lack Pol proofreading or MMR exhibit a 10-to 100-fold increase in spontaneous mutation rate (mutator phenotype), and inactivation of both Pol d proofreading (pol3-01) and MMR is lethal due to replication error-induced extinction (EEX). It is unclear whether a similar synthetic lethal relationship exists between defects in Pol e proofreading (pol2-4) and MMR. Using a plasmid-shuffling strategy in haploid Saccharomyces cerevisiae, we observed synthetic lethality of pol2-4 with alleles that completely abrogate MMR (msh2D, mlh1D, msh3D msh6D, or pms1D mlh3D) but not with partial MMR loss (msh3D, msh6D, pms1D, or mlh3D), indicating that high levels of unrepaired Pol e errors drive extinction. However, variants that escape this error-induced extinction (eex mutants) frequently emerged. Five percent of pol2-4 msh2D eex mutants encoded second-site changes in Pol e that reduced the pol2-4 mutator phenotype between 3-and 23-fold. The remaining eex alleles were extragenic to pol2-4. The locations of antimutator amino-acid changes in Pol e and their effects on mutation spectra suggest multiple mechanisms of mutator suppression. Our data indicate that unrepaired leading-and lagging-strand polymerase errors drive extinction within a few cell divisions and suggest that there are polymerase-specific pathways of mutator suppression. The prevalence of suppressors extragenic to the Pol e gene suggests that factors in addition to proofreading and MMR influence leading-strand DNA replication fidelity.O RGANISMS must accurately duplicate their genomes to avoid loss of long-term fitness. Consequently, cells employ high-fidelity DNA polymerases (Pols) equipped with proofreading exonucleases to replicate their DNA (reviewed in McCulloch and Kunkel 2008;Reha-Krantz 2010). Mismatch repair (MMR) further ensures the integrity of genetic information by targeting mismatches for excision from newly replicated DNA (reviewed in Kolodner and Marsischky 1999;Iyer et al. 2006;Hsieh and Yamane 2008). These polymerase error-correcting mechanisms, together with DNA damage repair (Friedberg et al. 2006), maintain the genome with less than one mutation per 10 9 nucleotides per cell division (Drake et al. 1998). Defects in proofreading or MMR result in mutator phenotypes characterized by increased rates of spontaneous mutation (Kolodner and Marsischky 1999;Iyer et al. 2006;Hsieh and Yamane 2008;McCulloch and Kunkel 2008; RehaKrantz 2010).Mutator phenotypes can be an important source of genetic diversity, which facilitates adaptation to environmental change. In bacterial and yeast populations, unstable environments favor mutator strains that readily acquire adaptive mutations (Chao and Cox 1983;Mao et al. 1997;Sniegowski et al. 1997...

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confidence: 99%

Emergence of DNA Polymerase ε Antimutators That Escape Error-Induced Extinction in Yeast

2013

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“…Inactivation of the MLH3 gene has been suggested to play a role in both male and female infertility [3] since the presence of the MLH3 C2531T polymorphism leads to an increased risk for developing infertility [6]. Human MLH3 (hMLH3) gene may also be associated to spermatogenesis and male infertility, while MLH3-MLH1 pathway seems to play a key role in making crossovers during mammalian meiosis [7] since it appears that this pathway directs an unknown factor that resolves Holliday junction and intermediates into crossovers [8]. There are scanty data in humans, regarding the association between certain hMLH3 polymorphisms and male infertility [7,9]; therefore, it is reasonable to assume that mutations and polymorphisms may impact negatively on spermatogenesis and subsequently on male fertility.…”

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confidence: 99%

Single-nucleotide polymorphism rs 175080 in the MLH3 gene and its relation to male infertility

Markandona

Dafopoulos

Anifandis

et al. 2015

J Assist Reprod Genet

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Purpose MLH3, a MutL homolog protein in mammals playing a role in DNA mismatch repair, is associated with spermatogenesis and male infertility. The purpose of the present study was to investigate the association of the singlenucleotide polymorphism (SNP), rs 175080 in the MLH3 gene, with sperm parameters in a Greek population. Methods The study included 300 men of couples undergoing in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) treatments (years 2011-2013). Genomic DNA was extracted from 300 peripheral blood samples, and conventional quantitative real-time PCR was performed for genotyping. Of them, 122 were from men used as Bcontrols^and 178 from men used as Bcases.^Allocation to the two groups was based on sperm concentrations (≥15 and <15 million/ml, respectively). Serum FSH, LH, estradiol, testosterone, and prolactin concentrations as well as sperm parameters were compared between three genotypes (GG, GA, and AA). Furthermore, the frequencies of these three genotypes were compared between Bcases^and Bcontrols.^R esults Anthropometric parameters and hormonal values did not differ significantly between the three genotypes. Significantly lower sperm concentrations were found in men with the AA genotype as compared to men with the GG and GA genotypes (p<0.001). The AA genotype had the lower progressive motility values as compared to the other two genotypes (p<0.05). Also, there was a significantly different distribution of the frequencies of the three genotypes between Bcases^and Bcontrols^(p<0.001). Conclusions It is suggested that the studied SNP in the MLH3 gene may be linked to oligozoospermia in Caucasian men of a certain area.

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“…Human Pms2 and its yeast homolog, Pms1p, have been shown to possess a latent endonuclease activity, conferred by a motif that is conserved among some of the MutL homologs, including Mlh3p (Kadyrov et al 2006(Kadyrov et al , 2007. Mutations in the DHQA(X) 2 E(X) 4 E motif in yeast MLH3 cause defects in both mismatch repair and meiotic recombination equivalent to mlh3D, suggesting that Mlh3p may also possess an endonuclease activity that is important for the generation of crossovers (Nishant et al 2008).…”

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Distinct Regulation of Mlh1p Heterodimers in Meiosis and Mitosis in Saccharomyces cerevisiae

2010

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Mlh1p forms three heterodimers that are important for mismatch repair (Mlh1p/Pms1p), crossing over during meiosis (Mlh1p/Mlh3p), and channeling crossover events into a specific pathway (Mlh1p/Mlh2p). All four proteins contain highly conserved ATPase domains and Pms1p has endonuclease activity. Studies of the functional requirements for Mlh1p/Pms1p in Saccharomyces cerevisae revealed an asymmetric contribution of the ATPase domains to repairing mismatches. Here we investigate the functional requirements of the Mlh1p and Mlh3p ATPase domains in meiosis by constructing separation of function mutations in Mlh3p. These mutations are analogous to mutations of Mlh1p that have been shown to lead to loss of ATP binding and/or ATP hydrolysis. Our data suggest that ATP binding by Mlh3p is required for meiotic crossing over while ATP hydrolysis is dispensable. This has been seen previously for Mlh1p. However, when mutations that affect ATP hydrolysis by both Mlh3p and Mlh1p are combined within a single cell, meiotic crossover frequencies are reduced. These observations suggest that the function of the Mlh1p/Mlh3p heterodimer requires both subunits to bind ATP but only one to efficiently hydrolyze it. Additionally, two different amino acid substitutions to the same residue (G97) in Mlh3p affect the minor mismatch repair function of Mlh3p while only one of them compromises its ability to promote crossing over. These studies thus reveal different functional requirements among the heterodimers formed by Mlh1p.

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A Mutation in the Putative MLH3 Endonuclease Domain Confers a Defect in Both Mismatch Repair and Meiosis inSaccharomyces cerevisiae

Cited by 126 publications

References 51 publications

Emergence of DNA Polymerase ε Antimutators That Escape Error-Induced Extinction in Yeast

Emergence of DNA Polymerase ε Antimutators That Escape Error-Induced Extinction in Yeast

Single-nucleotide polymorphism rs 175080 in the MLH3 gene and its relation to male infertility

Distinct Regulation of Mlh1p Heterodimers in Meiosis and Mitosis in Saccharomyces cerevisiae

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