Uracil-DNA glycosylase affects mismatch repair efficiency in transformation and bisulfite-induced mutagenesis in<i>Streptococus pneumoniae</i>

Méjean, Vincent; Devedjian, Jean-Christophe; Rives, I; Alloing, Geneviève; Claverys, Jean‐Pierre

doi:10.1093/nar/19.20.5525

Cited by 12 publications

(3 citation statements)

References 51 publications

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“…We believe that the latter interpretation is more likely. Indeed, when transforming pneumococcal DNA contains not only a single mismatch but also other types of (repairable) DNA modifications, the efficiency of the transformation of the low-efficiency marker increases, as would be expected if heteroduplex DNA were formed but other DNA repair activities altered the pattern of mismatch repair (34).…”

Section: Discussionmentioning

confidence: 95%

Gene targeting by linear duplex DNA frequently occurs by assimilation of a single strand that is subject to preferential mismatch correction

Leung

Malkova

Haber

1997

Proc. Natl. Acad. Sci. U.S.A.

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To study targeted recombination, a single linear 2-kb fragment of LEU2 DNA was liberated from a chromosomal site within the nucleus of Saccharomyces cerevisiae, by expression of the site-specific HO endonuclease. Gene targeting was scored by gene conversion of a chromosomal leu2 mutant allele by the liberated LEU2 fragment. This occurred at a frequency of only 2 ؋ 10 ؊4 , despite the fact that nearly all cells successfully repaired, by single-strand annealing, the chromosome break created by liberating the fragment. The frequency of Leu ؉ recombinants was 6-to 25-fold higher in pms1 strains lacking mismatch repair. In 70% of these cases, the colony was sectored for Leu ؉ ͞Leu ؊ . Similar results were obtained when a 4.1-kb fragment containing adjacent LEU2 and ADE1 genes was liberated, to convert adjacent leu2 and ade1 mutations on the chromosome. These results suggest that a linear fragment is not assimilated into the recipient chromosome by two crossovers each close to the end of the fragment; rather, heteroduplex DNA between the fragment and the chromosome is apparently formed over the entire region, by the assimilation of one of the two strands of the linear duplex DNA. Moreover, the recovery of Leu ؉ transformants is frequently defeated by the cell's mismatch repair machinery; more than 85% of mismatches in heteroduplex DNA are corrected in favor of the resident, unbroken (mutant) strand.Despite the fact that Saccharomyces is celebrated for its ability to carry out homologous recombination, the frequency of gene replacement by transformation of a linear exogenous DNA is surprisingly low (1-3). This could be due to several factors. For example, ''naked'' DNA, not yet associated with histones or other nuclear proteins, might be rapidly degraded before it has a chance to undergo recombination. Alternatively, the replacement of homologous DNA sequences may be an inherently inefficient process. Previously we showed that the frequency of gene replacement can be increased by providing additional copies of the target sequence (3), a result that suggests that the search for homology is a rate-limiting step in the process. In these and previous experiments it was also not known if there was a special subpopulation of cells that were especially adept at this process, either because they were more proficient in recombination or because they were able to take up more copies of the transforming DNA.To avoid some of the uncertainties inherent in transformation, we have devised a way to liberate a single linearized fragment of DNA from a chromosome within the nucleus and to examine its capacity to be ''captured'' by homologous recombination. The chromosomal region illustrated in Fig. 1A contains a LEU2 gene flanked by HO endonuclease recognition sites. When a galactose-inducible HO endonuclease is expressed, cleavage occurs at these sites, liberating a 2.0-kb LEU2 fragment and leaving a broken chromosome. The chromosomal break itself can be very efficiently repaired by the process of single-strand annealing (4-6), ...

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Section: Discussionmentioning

confidence: 95%

Gene targeting by linear duplex DNA frequently occurs by assimilation of a single strand that is subject to preferential mismatch correction

Leung

Malkova

Haber

1997

Proc. Natl. Acad. Sci. U.S.A.

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“…Nevertheless, the mechanism that generate access points for MutS/MutL in the leading strand is currently unknown. Interestingly, in Streptococcus pneumoniae the presence of uracil in the DNA strand that contains the incorrect base increases repair efficiency of mispairs ( Mèjean et al, 1991 ). Furthermore, in B cells of mice and humans, the activation-induced cytidine deaminase (AID) converts cytosine to uracil, generating multiple dU:dG mispairs.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Mismatch and Alternative Excision-Dependent Repair in Replicating Bacillus subtilis DNA Examined Under Conditions of Neutral Selection

Patlán-Vázquez

Ayala‐García²,

Vallin

et al. 2022

Front. Microbiol.

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Spontaneous DNA deamination is a potential source of transition mutations. In Bacillus subtilis, EndoV, a component of the alternative excision repair pathway (AER), counteracts the mutagenicity of base deamination-induced mispairs. Here, we report that the mismatch repair (MMR) system, MutSL, prevents the harmful effects of HNO2, a deaminating agent of Cytosine (C), Adenine (A), and Guanine (G). Using Maximum Depth Sequencing (MDS), which measures mutagenesis under conditions of neutral selection, in B. subtilis strains proficient or deficient in MutSL and/or EndoV, revealed asymmetric and heterogeneous patterns of mutations in both DNA template strands. While the lagging template strand showed a higher frequency of C → T substitutions; G → A mutations, occurred more frequently in the leading template strand in different genetic backgrounds. In summary, our results unveiled a role for MutSL in preventing the deleterious effects of base deamination and uncovered differential patterns of base deamination processing by the AER and MMR systems that are influenced by the sequence context and the replicating DNA strand.

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“…In our study, we observed a time-dependent increase of tandem double mutations until TDM constituted 91% of the total mutants and we have related them directly to the presence of uracil intermediates. Ung has previously been shown to be involved in repair of bisulfite-treated transforming DNA (Mejean et al, 1991;Chen & Shaw, 1993a). The ability to implicate uracil as an intermediate in bisulfite mutagenesis is an important feature of our studies.…”

Section: Discussionmentioning

confidence: 88%

Bisulfite Induces Tandem Double CC .fwdarw. TT Mutations in Double-Stranded DNA. 2. Kinetics of Cytosine Deamination

Hong¹,

Shaw²

1994

Biochemistry

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Deamination of cytosine to uracil in double-stranded DNA (ds DNA) by sodium bisulfite has been monitored with a sensitive genetic assay. In this system, reversion of a mutant in the lacZ alpha gene coding sequence of bacteriophage M13mp2 C141 was detected by employing an ung- bacterial strain defective in the enzyme uracil glycosylase. Within the 4-base target, it is possible to measure the rates of induction of C-->T, C-->A, C-->G, and CC-->TT mutations in DNA that has been incubated at physiological temperature and pH and then transfected into ung+ and ung- E. coli cells, respectively, for amplification and detection of the mutation. For concentrations of bisulfite from 1 to 50 mM, the reversion frequency in ung- cells increased linearly with time of incubation. The most interesting features of the bisulfite reaction were as follow: (1) Mutations were reduced 5-fold in ung+ cells, indicating ung is involved in repair of bisulfite-treated transforming DNA. (2) Sequencing of 157 revertants revealed that C-->T and tandem CC-->TT transition mutations comprised 100% of the mutations scored. (3) A unique finding was that, at the highest concentrations and longest incubation times, almost every mutant obtained in ds DNA exposed to bisulfite was found to be a CC-->TT tandem double mutation. (4) The high frequency of tandem double mutants is inconsistent with two random, independent mutational events and, coupled with the observed ung dependence, lends support to the concept of catalytic deamination, wherein bisulfite induces deamination in contiguous cytosines by a concerted mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

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Uracil-DNA glycosylase affects mismatch repair efficiency in transformation and bisulfite-induced mutagenesis inStreptococus pneumoniae

Cited by 12 publications

References 51 publications

Gene targeting by linear duplex DNA frequently occurs by assimilation of a single strand that is subject to preferential mismatch correction

Gene targeting by linear duplex DNA frequently occurs by assimilation of a single strand that is subject to preferential mismatch correction

Dynamics of Mismatch and Alternative Excision-Dependent Repair in Replicating Bacillus subtilis DNA Examined Under Conditions of Neutral Selection

Bisulfite Induces Tandem Double CC .fwdarw. TT Mutations in Double-Stranded DNA. 2. Kinetics of Cytosine Deamination

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