The wtf4 meiotic driver utilizes controlled protein aggregation to generate selective cell death

Abstract

Meiotic drivers are parasitic loci that force their own transmission into greater than half of the offspring of a heterozygote. Many drivers have been identified, but their molecular mechanisms are largely unknown. The wtf4 gene is a meiotic driver in Schizosaccharomyces pombe that uses a poison-antidote mechanism to selectively kill meiotic products (spores) that do not inherit wtf4. Here, we show that the Wtf4 proteins can function outside of gametogenesis and in a distantly related species, Saccharomyces cerevisiae. The Wtf4poison protein forms dispersed, toxic aggregates. The Wtf4antidote can co-assemble with the Wtf4poison and promote its trafficking to vacuoles. We show that neutralization of the Wtf4poison requires both co-assembly with the Wtf4antidote and aggregate trafficking, as mutations that disrupt either of these processes result in cell death in the presence of the Wtf4 proteins. This work reveals that wtf parasites can exploit protein aggregate management pathways to selectively destroy spores.

S. pombe wtf genes use dual transcriptional regulation and selective protein exclusion from spores to cause meiotic drive

“…We depict Wtf4 antidote in magenta and Wtf4 poison in cyan and this will be true for all images in this text regardless of fluorescent protein tag. This analysis confirmed our previous gross observations of early and late meiotic time points ( Nuckolls et al, 2017; Nuckolls et al, 2020 ), in which we observed Wtf4 poison -GFP prior to the bulk of the mCherry-Wtf4 antidote signal. Indeed, we saw Wtf4 poison -GFP hours before mCherry-Wtf4 antidote and given that GFP maturation is only minutes faster than mCherry ( Badrinarayanan et al, 2012; Khmelinskii et al, 2012; Shashkova et al, 2018 ), the earlier expression of Wtf4 poison -GFP cannot be explained by maturation times of the fluorescent proteins alone.…”

“…In previous work, we used fluorescent markers to separately tag and visualize the Wtf4 proteins ( Nuckolls et al, 2017, Nuckolls et al, 2020 ). In that work, we found that the Wtf4 poison -GFP protein is present at low levels in diploid cells induced to undergo meiosis.…”

“…Images shown at ∼ 4 hours (diploid), ∼8 hours (immature ascus), and ∼12 hours (mature ascus) post-induction in sporulation media. Distinct images for these strains were first presented in ( Nuckolls et al, 2017 ) and a distinct meiotic timelapse of these strains was also presented in ( Nuckolls et al, 2020 ). ( D ) Images of a heterozygous wtf4 antidote -mCherry/ura+, wtf4 poison -GFP/ade6+ diploid cell, an immature ascus, and a mature ascus.…”

A genome‐scale yeast library with inducible expression of individual genes

“…Since b-estradiol is not a yeast metabolite or signaling molecule, cellular metabolism is not perturbed (McIsaac et al, 2013b). ZEVs have been widely used for basic and applied research, including studies of gene regulatory networks (Hackett et al, 2020;Kang et al, 2020;Ma & Brent, 2020), individual gene function (Elfving et al, 2014;Lyon et al, 2016;Weir et al, 2017;Tran et al, 2018;Kim et al, 2019;Smith et al, 2020;Wang et al, 2020;Kira et al, 2021), gene regulation (Carey, 2015;Hendrickson et al, 2018a;Schikora-Tamarit et al, 2018;Lutz et al, 2019;Brion et al, 2020;preprint: Leydon et al, 2021), metabolic engineering (Liu et al, 2020), synthetic biology (Schikora-Tamarit et al, 2016;Aranda-D ıaz et al, 2017;Gander et al, 2017;Pothoulakis & Ellis, 2018;Bashor et al, 2019;Kotopka & Smolke, 2020;Shaw et al, 2019;Yang et al, 2019), biocontainment (Agmon et al, 2017), living materials (Gilbert et al, 2021), highthroughput screening (Younger et al, 2017;Staller et al, 2018), and they have also been adapted to fission yeast (Ohira et al, 2017;G omez-Gil et al, 2020;Nuckolls et al, 2020) and Pichia pastoris (Perez-Pinera et al, 2016).…”

An introgressed gene causes meiotic drive inNeurospora sitophila

“…We have found no obvious mechanism behind either the killing or resistance phenotypes, but the gene carries predicted transmembrane domains, presenting the possibility that it could disrupt membrane integrity, as has been observed in some bacterial toxin–antitoxin systems ( 37 , 38 ). On the other hand, the wtf genes in Schizosaccharomyces were initially also predicted to contain transmembrane domains ( 13 ), but recent work has shown that these are hydrophobic regions which are important for forming large toxic protein aggregates essential for spore killing ( 39 ), and a similar mechanism might be at play here as well.…”