scholarly journals Functional Overlap in Mismatch Repair by Human MSH3 and MSH6

Genetics ◽  
1998 ◽  
Vol 148 (4) ◽  
pp. 1637-1646 ◽  
Author(s):  
Asad Umar ◽  
John I Risinger ◽  
Warren E Glaab ◽  
Kenneth R Tindall ◽  
J Carl Barrett ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Microsatellite Loci ◽  
Tumor Cell Line ◽  
Mutation Rates ◽  
Wild Type ◽  
Chromosome 5 ◽  
Replication Errors ◽  
Repeat Units ◽  
Human Genes ◽  
Hprt Locus

Abstract Three human genes, hMSH2, hMSH3, and hMSH6, are homologues of the bacterial MutS gene whose products bind DNA mismatches to initiate strand-specific repair of DNA replication errors. Several studies suggest that a complex of hMSH2·hMSH6 (hMutSα) functions primarily in repair of base·base mismatches or single extra bases, whereas a hMSH2·hMSH3 complex (hMutSβ) functions chiefly in repair of heteroduplexes containing two to four extra bases. In the present study, we compare results with a tumor cell line (HHUA) that is mutant in both hMSH3 and hMSH6 to results with derivative clones containing either wild-type hMSH3 or wild-type hMSH6, introduced by microcell-mediated transfer of chromosome 5 or 2, respectively. HHUA cells exhibit marked instability at 12 different microsatellite loci composed of repeat units of 1 to 4 base pairs. Compared to normal cells, HHUA cells have mutation rates at the HPRT locus that are elevated 500-fold for base substitutions and 2400-fold for single-base frameshifts. Extracts of HHUA cells are defective in strand-specific repair of substrates containing base·base mismatches or 1–4 extra bases. Transfer of either chromosome 5 (hMSH3) or 2 (hMSH6) into HHUA cells partially corrects instability at the microsatellite loci and also the substitution and frameshift mutator phenotypes at the HPRT locus. Extracts of these lines can repair some, but not all, heteroduplexes. The combined mutation rate and mismatch repair specificity data suggest that both hMSH3 and hMSH6 can independently participate in repair of replication errors containing base·base mismatches or 1–4 extra bases. Thus, these two gene products share redundant roles in controlling mutation rates in human cells.

scholarly journals Frameshift intermediates in homopolymer runs are removed efficiently by yeast mismatch repair proteins.

1997 ◽  
Vol 17 (5) ◽  
pp. 2844-2850 ◽  
Author(s):  
C N Greene ◽  
S Jinks-Robertson
Keyword(s):  
Mismatch Repair ◽  
Wild Type Strain ◽  
Frameshift Mutation ◽  
Protein A ◽  
Repair System ◽  
Wild Type ◽  
Base Pairs ◽  
Replication Errors ◽  
Mismatch Repair System ◽  
Mismatch Repair Proteins

A change in the number of base pairs within a coding sequence can result in a frameshift mutation, which almost invariably eliminates the function of the encoded protein. A frameshift reversion assay with Saccharomyces cerevisiae that can be used to examine the types of insertions and deletions that are generated during DNA replication, as well as the editing functions that remove such replication errors, has been developed. Reversion spectra have been obtained in a wild-type strain and in strains defective for defined components of the postreplicative mismatch repair system (msh2, msh3, msh6, msh3 msh6, pms1, and mih1 mutants). Comparison of the spectra reveals that yeast mismatch repair proteins preferentially remove frameshift intermediates that arise in homopolymer tracts and indicates that some of the proteins have distinct substrate or context specificities.

scholarly journals The msh2 Gene ofSchizosaccharomyces pombe Is Involved in Mismatch Repair, Mating-Type Switching, and Meiotic Chromosome Organization

1999 ◽  
Vol 19 (1) ◽  
pp. 241-250 ◽  
Author(s):  
Claudia Rudolph ◽  
Christophe Kunz ◽  
Sandro Parisi ◽  
Elisabeth Lehmann ◽  
Edgar Hartsuiker ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Mating Type ◽  
Meiotic Chromosome ◽  
Binding Activity ◽  
Mutation Rates ◽  
Wild Type ◽  
Cell Extracts ◽  
In The Wild ◽  
Mating Type Switching ◽  
Postmeiotic Segregation

ABSTRACT We have identified in the fission yeast Schizosaccharomyces pombe a MutS homolog that shows highest homology to the Msh2 subgroup. msh2 disruption gives rise to increased mitotic mutation rates and increased levels of postmeiotic segregation of genetic markers. In bandshift assays performed with msh2Δ cell extracts, a general mismatch-binding activity is absent. By complementation assays, we showed that S. pombe msh2 is allelic with the previously identified swi8 andmut3 genes, which are involved in mating-type switching. The swi8-137 mutant has a mutation in the msh2gene which causes a truncated Msh2 peptide lacking a putative DNA-binding domain. Cytological analysis revealed that during meiotic prophase of msh2-defective cells, chromosomal structures were frequently formed; such structures are rarely found in the wild type. Our data show that besides having a function in mismatch repair,S. pombe msh2 is required for correct termination of copy synthesis during mating-type switching as well as for proper organization of chromosomes during meiosis.

scholarly journals Human mismatch repair system corrects errors produced during lagging strand replication more effectively

2016 ◽  
Author(s):  
Maria Andrianova ◽  
Georgii A Bazykin ◽  
Sergey Nikolaev ◽  
Vladimir Seplyarskiy
Keyword(s):  
Mismatch Repair ◽  
Mutation Rates ◽  
Repair System ◽  
Wild Type ◽  
Strand Asymmetry ◽  
Exonuclease Domain ◽  
Mismatch Repair System ◽  
Dna Strands ◽  
Leading Strand ◽  
Lagging Strand

Mismatch repair (MMR) is one of the main systems maintaining fidelity of replication. Different effectiveness in correction of errors produced during replication of the leading and the lagging DNA strands was reported in yeast, but this effect is poorly studied in humans. Here, we use MMR-deficient (MSI) and MMR-proficient (MSS) cancer samples to investigate properties of the human MMR. MSI, but not MSS, cancers demonstrate unequal mutation rates between the leading and the lagging strands. The direction of strand asymmetry in MSI cancers matches that observed in cancers with mutated exonuclease domain of polymerase δ, indicating that polymerase δ contributes more mutations than its leading-strand counterpart, polymerase ε. As polymerase δ primarily synthesizes DNA during the lagging strand replication, this implies that mutations produced in wild type cells during lagging strand replication are repaired by the MMR ~3 times more effectively, compared to those produced on the leading strand.

scholarly journals Mapping the Polarity of Changes That Occur in Interrupted CAG Repeat Tracts in Yeast

1998 ◽  
Vol 18 (8) ◽  
pp. 4597-4604 ◽  
Author(s):  
Debra J. Maurer ◽  
Brennon L. O’Callaghan ◽  
Dennis M. Livingston
Keyword(s):  
Mismatch Repair ◽  
Trinucleotide Repeat ◽  
Cag Repeat ◽  
Yeast Cells ◽  
Wild Type ◽  
Repeat Tract ◽  
Repeat Units ◽  
Length Changes ◽  
Mutant Cells ◽  
Lagging Strand

ABSTRACT To explore the mechanisms by which CAG trinucleotide repeat tracts undergo length changes in yeast cells, we examined the polarity of alterations with respect to an interrupting CAT trinucleotide near the center of the tract. In wild-type cells, in which most tract changes are large contractions, the changes that retain the interruption are biased toward the 3′ end of the repeat tract (in reference to the direction of lagging-strand synthesis). In rth1/rad27mutant cells that are defective in Okazaki fragment maturation, the tract expansions are biased to the 5′ end of the repeat tract, while the tract contractions that do not remove the interruption occur randomly on either side of the interruption. In msh2 mutant cells that are defective in the mismatch repair machinery, neither the small changes of one or two repeat units nor the larger contractions attributable to this mutation are biased to either side of the interruption. The results of this study are discussed in terms of the molecular paths leading to expansions and contractions of repeat tracts.

scholarly journals Stability across the Whole Nuclear Genome in the Presence and Absence of DNA Mismatch Repair

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1224
Author(s):  
Scott Alexander Lujan ◽  
Thomas A. Kunkel
Keyword(s):  
Cell Division ◽  
Cell Line ◽  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Nuclear Genome ◽  
Mutation Accumulation ◽  
Mutation Rates ◽  
Wild Type ◽  
Dna Mismatch ◽  
Chicken Cell

We describe the contribution of DNA mismatch repair (MMR) to the stability of the eukaryotic nuclear genome as determined by whole-genome sequencing. To date, wild-type nuclear genome mutation rates are known for over 40 eukaryotic species, while measurements in mismatch repair-defective organisms are fewer in number and are concentrated on Saccharomyces cerevisiae and human tumors. Well-studied organisms include Drosophila melanogaster and Mus musculus, while less genetically tractable species include great apes and long-lived trees. A variety of techniques have been developed to gather mutation rates, either per generation or per cell division. Generational rates are described through whole-organism mutation accumulation experiments and through offspring–parent sequencing, or they have been identified by descent. Rates per somatic cell division have been estimated from cell line mutation accumulation experiments, from systemic variant allele frequencies, and from widely spaced samples with known cell divisions per unit of tissue growth. The latter methods are also used to estimate generational mutation rates for large organisms that lack dedicated germlines, such as trees and hyphal fungi. Mechanistic studies involving genetic manipulation of MMR genes prior to mutation rate determination are thus far confined to yeast, Arabidopsis thaliana, Caenorhabditis elegans, and one chicken cell line. A great deal of work in wild-type organisms has begun to establish a sound baseline, but far more work is needed to uncover the variety of MMR across eukaryotes. Nonetheless, the few MMR studies reported to date indicate that MMR contributes 100-fold or more to genome stability, and they have uncovered insights that would have been impossible to obtain using reporter gene assays.

Requirement for Msh6, but Not for Swi4 (Msh3), in Msh2-Dependent Repair of Base-Base Mismatches and Mononucleotide Loops inSchizosaccharomyces pombe

Genetics ◽  
2001 ◽  
Vol 158 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Carine Tornier ◽  
Stéphanie Bessone ◽  
Isabelle Varlet ◽  
Claudia Rudolph ◽  
Michel Darmon ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mismatch Repair ◽  
Recombination Frequency ◽  
Mutation Rates ◽  
Base Substitution ◽  
Mismatch Repair Gene ◽  
Repair Pathway ◽  
Wild Type ◽  
Tetrad Analysis ◽  
Repair Gene

AbstractThe msh6 mismatch repair gene of Schizosaccharomyces pombe was cloned, sequenced, and inactivated. Strains bearing all combinations of inactivated msh6, msh2, and swi4 (the S. pombe MSH3 ortholog) alleles were tested for their defects in mitotic and meiotic mismatch repair. Mitotic mutation rates were similarly increased in msh6 and msh2 mutants, both for reversion of a base-base substitution as well as of an insertion of one nucleotide in a mononucleotide run. Tetrad analysis and intragenic two-factor crosses revealed that meiotic mismatch repair was affected in msh6 to the same extent as in msh2 background. In contrast, loss of Swi4 likely did not cause a defect in mismatch repair, but rather resulted in reduced recombination frequency. Consistently, a mutated swi4 caused a two- to threefold reduction of recombinants in intergenic crosses, while msh2 and msh6 mutants were not significantly different from wild type. In summary, our study showed that Msh6 plays the same important role as Msh2 in the major mismatch repair pathway of S. pombe, while Swi4 rather functions in recombination.

scholarly journals Analysis of Conditional Mutations in the Saccharomyces cerevisiae MLH1 Gene in Mismatch Repair and in Meiotic Crossing Over

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 909-921 ◽  
Author(s):  
Juan Lucas Argueso ◽  
Daniel Smith ◽  
James Yi ◽  
Marc Waase ◽  
Sumeet Sarin ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Family ◽  
Mismatch Repair ◽  
Mutational Analysis ◽  
Mutation Rates ◽  
Temperature Sensitive ◽  
Crossing Over ◽  
Wild Type ◽  
Genetic Studies ◽  
Conditional Mutations

Abstract In mismatch repair (MMR), members of the MLH gene family have been proposed to act as key molecular matchmakers to coordinate mismatch recognition with downstream repair functions that result in mispair excision. Two members of this gene family, MLH1 and MLH3, have also been implicated in meiotic crossing over. These diverse roles suggest that a mutational analysis of MLH genes could provide reagents required to identify interactions between gene products and to test whether the different roles ascribed to a subset of these genes can be separated. In this report we show that in Saccharomyces cerevisiae the mlh1Δ mutation confers inviability in pol3-01 strain backgrounds that are defective in the Polδ proofreading exonuclease activity. This phenotype was exploited to identify four mlh1 alleles that each confer a temperature-sensitive phenotype for viability in pol3-01 strains. In three different mutator assays, strains bearing conditional mlh1 alleles displayed wild-type or nearly wild-type mutation rates at 26°. At 35°, these strains exhibited mutation rates that approached those observed in mlh1Δ mutants. The mutator phenotype exhibited in mlh1-I296S strains was partially suppressed at 35° by EXO1 overexpression. The mlh1-F228S and -I296S mutations conferred a separation-of-function phenotype in meiosis; both mlh1-F228S and -I296S strains displayed strong defects in meiotic mismatch repair but showed nearly wild-type levels of crossing over, suggesting that the conditional mutations differentially affected MLH1 functions. These genetic studies suggest that the conditional mlh1 mutations can be used to separate the MMR and meiotic crossing-over functions of MLH1 and to identify interactions between MLH1 and downstream repair components.

scholarly journals Human mismatch-repair protein MutL homologue 1 (MLH1) interacts with Escherichia coli MutL and MutS in vivo and in vitro: a simple genetic system to assay MLH1 function

2003 ◽  
Vol 371 (1) ◽  
pp. 183-189 ◽  
Author(s):  
Barbara QUARESIMA ◽  
Pietro ALIFANO ◽  
Pierfrancesco TASSONE ◽  
Enrico V. AVVEDIMENTO ◽  
Francesco S. COSTANZO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mismatch Repair ◽  
Fold Increase ◽  
Genetic System ◽  
Mutation Rates ◽  
Wild Type ◽  
Mismatched Dna ◽  
Repair Protein

A simple genetic system has been developed to test the effect of over-expression of wild-type or mutated human MutL homologue 1 (hMLH1) proteins on methyl-directed mismatch repair (MMR) in Escherichia coli. The system relies on detection of Lac+ revertants using MMR-proficient or MMR-deficient E. coli strains carrying a lac +1 frameshift mutation expressing hMLH1 proteins. We report that expression of wild-type hMLH1 protein causes an approx. 19-fold increase in mutation rates. The mutator phenotype was due to the ability of hMLH1 protein to interact with bacterial MutL and MutS proteins, thereby interfering with the formation of complexes between MMR proteins and mismatched DNA. Conversely, expression of proteins encoded by alleles deriving from hereditary-non-polyposis-colon-cancer (HNPCC) families decreases mutation rates, depending on the specific amino acid substitutions. These effects parallel the MutL-and MutS-binding and ATP-binding/hydrolysis activities of the mutated proteins.

Humanizing mismatch repair in yeast: towards effective identification of hereditary non-polyposis colorectal cancer alleles

2007 ◽  
Vol 35 (6) ◽  
pp. 1525-1528 ◽  
Author(s):  
P.M.R. Aldred ◽  
R.H. Borts
Keyword(s):  
Colorectal Cancer ◽  
Mismatch Repair ◽  
Model Organism ◽  
Mismatch Repair Genes ◽  
Functional Effect ◽  
Replication Errors ◽  
Colon Cancers ◽  
Human Genes ◽  
Yeast Genes ◽  
Repair Genes

The correction of replication errors is an essential component of genetic stability. This is clearly demonstrated in humans by the observation that mutations in mismatch repair genes lead to HNPCC (hereditary non-polyposis colorectal cancer). This disease accounts for as many as 2–3% of colon cancers. Of these, most of them are in the two central components of mismatch repair, MLH1 (mutLhomologue 1) and MSH2 (mutShomologue 2). MLH1 and MSH2 function as a complex with two other genes PMS2 and MSH6. Mismatch repair genes, and the mechanism that ensures that incorrectly paired bases are removed, are conserved from prokaryotes to human. Thus yeast can serve as a model organism for analysing mutations/polymorphisms found in human mismatch repair genes for their effect on post-replicative repair. To date, this has predominantly been accomplished by making the analogous mutations in yeast genes. However, this approach is only useful for the most highly conserved regions. Here, we discuss some of the benefits and technical difficulties involved in expressing human genes in yeast. Modelling human mismatch repair in yeast will allow the assessment of any functional effect of novel polymorphisms found in patients diagnosed with colon cancers.

The Budding Yeast Msh4 Protein Functions in Chromosome Synapsis and the Regulation of Crossover Distribution

Genetics ◽  
2001 ◽  
Vol 158 (3) ◽  
pp. 1013-1025 ◽  
Author(s):  
Janet E Novak ◽  
Petra B Ross-Macdonald ◽  
G Shirleen Roeder
Keyword(s):  
Mismatch Repair ◽  
Budding Yeast ◽  
Null Mutation ◽  
Crossing Over ◽  
Wild Type ◽  
Crossover Interference ◽  
Meiotic Chromosomes ◽  
Chromosome Synapsis ◽  
Protein Functions ◽  
Or Gene

AbstractThe budding yeast MSH4 gene encodes a MutS homolog produced specifically in meiotic cells. Msh4 is not required for meiotic mismatch repair or gene conversion, but it is required for wild-type levels of crossing over. Here, we show that a msh4 null mutation substantially decreases crossover interference. With respect to the defect in interference and the level of crossing over, msh4 is similar to the zip1 mutant, which lacks a structural component of the synaptonemal complex (SC). Furthermore, epistasis tests indicate that msh4 and zip1 affect the same subset of meiotic crossovers. In the msh4 mutant, SC formation is delayed compared to wild type, and full synapsis is achieved in only about half of all nuclei. The simultaneous defects in synapsis and interference observed in msh4 (and also zip1 and ndj1/tam1) suggest a role for the SC in mediating interference. The Msh4 protein localizes to discrete foci on meiotic chromosomes and colocalizes with Zip2, a protein involved in the initiation of chromosome synapsis. Both Zip2 and Zip1 are required for the normal localization of Msh4 to chromosomes, raising the possibility that the zip1 and zip2 defects in crossing over are indirect, resulting from the failure to localize Msh4 properly.

Sign in / Sign up

Export Citation Format

Share Document