MUTATOR GENE STUDIES IN <i>ESCHERICHIA COLI</i>: THE <i>mutS</i> GENE

Cox, Edward C.; Degnen, Gerald E.; Scheppe, Mary L.

doi:10.1093/genetics/72.4.551

Cited by 72 publications

(7 citation statements)

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“…Finally, the difference in our estimates from those of Kibota & Lynch (1996) could also be due to the type of mutations that are increased by a deficiency in the mismatch repair genes. It is known that strains without a functional mutS gene have a higher rate of transitions (Cox et al 1972) and these mutations might, on average, have a more deleterious effect than the mutations to which the wild-type strains are exposed. Interestingly, when analysing mutations caused by random transposon insertions (involving the Tn10 element), Elena & Lenski (1997) estimated a mean s d of about 0.03, which is similar to our estimate.…”

Section: Discussionmentioning

confidence: 99%

Rate and effects of spontaneous mutations that affect fitness in mutatorEscherichia coli

Trindade

Perfeito

Gordo

2010

Phil. Trans. R. Soc. B

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Knowledge of the mutational parameters that affect the evolution of organisms is of key importance in understanding the evolution of several characteristics of many natural populations, including recombination and mutation rates. In this study, we estimated the rate and mean effect of spontaneous mutations that affect fitness in a mutator strain of Escherichia coli and review some of the estimation methods associated with mutation accumulation (MA) experiments. We performed an MA experiment where we followed the evolution of 50 independent mutator lines that were subjected to repeated bottlenecks of a single individual for approximately 1150 generations. From the decline in mean fitness and the increase in variance between lines, we estimated a minimum mutation rate to deleterious mutations of 0.005 (+0.001 with 95% confidence) and a maximum mean fitness effect per deleterious mutation of 0.03 (+0.01 with 95% confidence). We also show that any beneficial mutations that occur during the MA experiment have a small effect on the estimate of the rate and effect of deleterious mutations, unless their rate is extremely large. Extrapolating our results to the wild-type mutation rate, we find that our estimate of the mutational effects is slightly larger and the inferred deleterious mutation rate slightly lower than previous estimates obtained for non-mutator E. coli.

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Section: Discussionmentioning

confidence: 99%

Rate and effects of spontaneous mutations that affect fitness in mutatorEscherichia coli

Trindade

Perfeito

Gordo

2010

Phil. Trans. R. Soc. B

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“…In bacteria, deletion of MMR genes results in a several hundred-fold increase in mutation frequency (Cox et al, 1972). In humans, several primary tumors from cancers including hereditary nonpolyposis colorectal carcinoma (HNPCC) and Turcot syndrome (Fishel et al, 1993;Hamilton et al, 1995) have MMR defects, suggesting that increased mutation frequency could contribute to the development of these cancers.…”

Section: Introductionmentioning

confidence: 99%

β Clamp Directs Localization of Mismatch Repair in Bacillus subtilis

et al. 2008

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MutS homologs function in several cellular pathways including mismatch repair (MMR), the process by which mismatches introduced during DNA replication are corrected. We demonstrate that the C terminus of Bacillus subtilis MutS is necessary for an interaction with beta clamp. This interaction is required for MutS-GFP focus formation in response to mismatches. Reciprocally, we show that a mutant of the beta clamp causes elevated mutation frequencies and is reduced for MutS-GFP focus formation. MutS mutants defective for interaction with beta clamp failed to support the next step of MMR, MutL-GFP focus formation. We conclude that the interaction between MutS and beta is the major molecular interaction facilitating focus formation and that beta clamp aids in the stabilization of MutS at a mismatch in vivo. The striking ability of the MutS C terminus to direct focus formation at replisomes by itself, suggests that it is mismatch recognition that licenses MutS's interaction with beta clamp.

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“…For example, the Treffers' mutator in E. coli K-12 (TREFFERS, SPINELLI and BELSER 1954) causes a unidirectional change-an AT -) CG transversion (YANOFSKY, Cox and HORN 1966). More recently, Cox, DEGNEN and SCHEPPE (1972) have demonstrated that another E. coli mutator gene, mutS1, yields transitions, confirming the mutagen specificity work of SIEGEL and BRYSON (1 964). However, they showed that not all A: T pairs are equally susceptible; thus, nearest neighbors may influence the mutator action.…”

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confidence: 76%

MUTATORS IN SACCHAROMYCES CEREVISIAE: MUT1–1, MUT1–2 AND MUT2–1

Gottlieb

Borstel

1976

Genetics

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The purpose of this study was to characterize two mutator stocks of yeast which were induced and selected on the basis of high spontaneous reversion rates of the suppressible "ochre" nonsense allele lys1-1. In the mutator stock VA-3, a single mutation, designated mut1-1, is responsible for the increase in the reversion rate of the ochre alleles lys1-1 and arg4-17. In stock VA-105, there are two separate mutator mutations. Tetrad analysis data showed these two loci are loosely linked. Based on complementation data, one of these mutations is at the same locus as mut1-1 and designated mut1-2. The second mutator of stock VA-105 was designated mut2-1. All three mutators are recessive. Both mut1-1 and mut1-2 give a high mutation rate for ochre nonsense suppressor (SUP) loci, but not for the ochre nonsense alleles. On the contrary, the mutation rates of the ochre alleles are greatly reduced. With the mutant mut2-1 there were mutations at both the lys1-1site and its suppressors; mut2-1 is as effective as mut1-2but not as effective as mut1-1 in inducing reversions of a missense mutant, his1-7. Neither mut1-1, mut1-2 nor mut2-1 were effective in inducing reversions of a putative frameshift mutation, hom3-10, or in inducing forward mutations to canavanine resistance.

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MUTATOR GENE STUDIES IN ESCHERICHIA COLI: THE mutS GENE

Cited by 72 publications

References 0 publications

Rate and effects of spontaneous mutations that affect fitness in mutatorEscherichia coli

Rate and effects of spontaneous mutations that affect fitness in mutatorEscherichia coli

β Clamp Directs Localization of Mismatch Repair in Bacillus subtilis

MUTATORS IN SACCHAROMYCES CEREVISIAE: MUT1–1, MUT1–2 AND MUT2–1

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