The frenemies within: viruses, retrotransposons and plasmids that naturally infectSaccharomycesyeasts

Abstract

Viruses are a major focus of current research efforts because of their detrimental impact on humanity and their ubiquity within the environment. Bacteriophages have long been used to study host-virus interactions within microbes, but it is often forgotten that the single-celled eukaryote Saccharomyces cerevisiae and related species are infected with double-stranded RNA viruses, single-stranded RNA viruses, LTR-retrotransposons and double-stranded DNA plasmids. These intracellular nucleic acid elements have some similarities to higher eukaryotic viruses, i.e. yeast retrotransposons have an analogous lifecycle to retroviruses, the particle structure of yeast totiviruses resembles the capsid of reoviruses and segregation of yeast plasmids is analogous to segregation strategies used by viral episomes. The powerful experimental tools available to study the genetics, cell biology and evolution of S. cerevisiae are well suited to further our understanding of how cellular processes are hijacked by eukaryotic viruses, retrotransposons and plasmids. This article has been written to briefly introduce viruses, retrotransposons and plasmids that infect Saccharomyces yeasts, emphasize some important cellular proteins and machineries with which they interact, and suggest the evolutionary consequences of these interactions. Copyright © 2017 John Wiley & Sons, Ltd.

The ecology of killer yeasts: Interference competition in natural habitats

“…Plasmids, L-A viruses, and M viruses have been discovered through visualization of different sized fragments among a strain's total extracted DNA or dsRNA (Maqueda, Zamora, Alvarez, & Ramirez, 2012;Wésolowski, Algeri, Goffrini, & Fukuhara, 1982). Fragments can be subsequently identified using sequencing or northern blots (Rodríguez-Cousiño, Gómez, & Esteban, 2013, 2017. In some cases, researchers have detected putative killer viruses in cells without a killer phenotype (Maqueda et al, 2012).…”

“…However, the killer phenomenon has been a model system for yeast cell biology for decades, and there are a variety of reviews on killer yeasts in the literature for interested readers. These include reviews focusing on mechanisms of toxin production and activity (Magliani et al, 1997;Marquina, Santos, & Peinado, 2002;Schmitt & Breinig, 2006;Stark, Boyd, Mileham, & Romanos, 1990), the diversity and biology of yeast cytoplasmic elements and toxins (Klassen et al, 2017;Rowley, 2017;Wickner, 1996), and the role of killers in applied biotechnology (El-Banna, Malak, & Shehata, 2011).…”

Saccharomyces cerevisiae killer toxins: synthesis, mechanisms of action and practical use

“…Дальнейшие исследования показали, что Xrn1p взаимодействует с белком оболочки вирусов Gag. Этот факт свидетельствует о более сложных взаимодействиях между клеткой дрожжей и вирусом, а не о простом нуклеазном расщеплении вирусной РНК [55,56]. Таким образом, отсутствие системы РНК-интерференции у дрожжей, по-видимому, в процессе эволюции компенсируется другими механизмами.…”

A natural variant of the essential host geneMMS21restricts the parasitic 2-micron plasmid inSaccharomyces cerevisiae

“…Budding yeasts provide an ideal system to study host-SGE genetic conflicts, with abundant genetic tools, together with resources for comparative and population genetics. Yeast harbor a variety of SGEs including retrotransposable elements, RNA viruses and 2-micron plasmids [13][14][15][16][17][18] . Yet, despite its long history as a popular model eukaryote, variation in cellular immunity factors against SGEs have been largely uncharacterized in S. cerevisiae and related species, with a few notable exceptions [19][20][21][22][23] .…”