Antagonistic coevolution with selfish genetic elements (SGEs) can drive evolution of host resistance. Here, we investigated host suppression of 2-micron (2m) plasmids, multicopy nuclear parasites that have co-evolved with budding yeasts. We developed SCAMPR (Single-Cell Assay for Measuring Plasmid Retention) to measure copy number heterogeneity and 2m plasmid loss in live cells. We identified three S. cerevisiae strains that lack endogenous 2m plasmids and reproducibly inhibit mitotic plasmid stability. Focusing on the Y9 ragi strain, we determined that plasmid restriction is heritable and dominant. Using bulk segregant analysis, we identified a high-confidence Quantitative Trait Locus (QTL) with a single variant of MMS21 associated with increased 2m instability. MMS21 encodes a SUMO E3 ligase and an essential component of the Smc5/6 complex, involved in sister chromatid cohesion, chromosome segregation, and DNA repair. Our analyses leverage natural variation to uncover a novel means by which budding yeasts can overcome highly successful genetic parasites.
- Harmit S Malik
- Michelle Hays
- Michelle Hays
- Harmit S Malik
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Christian R Landry, Université Laval, Canada
- Received: August 23, 2020
- Accepted: October 15, 2020
- Accepted Manuscript published: October 16, 2020 (version 1)
© 2020, Hays et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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