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Incompatibilities in Mismatch Repair Genes MLH1-PMS1 Contribute to a Wide Range of Mutation Rates in Human Isolates of Baker’s Yeast.

A new interesting article has been published in Genetics. 2018 Oct 22. pii: genetics.301550.2018. doi: 10.1534/genetics.118.301550. [Epub ahead of print] and titled:

Incompatibilities in Mismatch Repair Genes MLH1-PMS1 Contribute to a Wide Range of Mutation Rates in Human Isolates of Baker’s Yeast.

Authors of this article are:

Raghavan V, Bui DT, Al-Sweel N, Friedrich A, Schacherer J, Aquadro CF, Alani E.

A summary of the article is shown below:

Laboratory baker’s yeast strains bearing an incompatible combination of MLH1 and PMS1 mismatch repair alleles are mutators that can adapt more rapidly to stress but do so at the cost of long-term fitness. We identified 18 baker’s yeast isolates from 1011 surveyed that contain the incompatible MLH1-PMS1 genotype in a heterozygous state. Surprisingly, the incompatible combination from two human clinical heterozygous diploid isolates, YJS5845 and YJS5885, contain the exact MLH1 (S288c derived) and PMS1 (SK1 derived) open reading frames originally shown to confer incompatibility. While these isolates were non-mutators, their meiotic spore clone progeny displayed mutation rates in a DNA slippage assay that varied over a 340-fold range. This range was 30-fold higher than observed between compatible and incompatible combinations of laboratory strains. Genotyping analysis indicated that MLH1-PMS1 incompatibility was the major driver of mutation rate in the isolates. The variation in the mutation rate of incompatible spore clones could be due to background suppressors and enhancers as well as aneuploidy seen in the spore clones. Our data are consistent with the observed variance in mutation rate contributing to adaptation to stress conditions (e.g. in a human host) through the acquisition of beneficial mutations, with high mutation rates leading to long-term fitness costs that are buffered by mating, or eliminated through natural selection.

Check out the article’s website on Pubmed for more information:



This article is a good source of information and a good way to become familiar with topics such as:

DNA mismatch repair;Saccharomyces cerevisiae;adaptation;genetic Incompatibility;mutation rate;natural yeast isolates

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