GSE121899
Distinct Adaptive Mechanisms Drive Recovery from Aneuploidy Caused by Loss of the Ulp2 SUMO Protease [WGS]
In response to acute loss of the Ulp2 SUMO-specific protease, yeast become disomic for chromosome I (ChrI) and ChrXII. Here we report that ChrI disomy, which creates an adaptive advantage in part by increasing the dosage of the Ccr4 deadenylase, was eliminated by extended passaging. Loss of aneuploidy is often accompanied by mutations in essential SUMO-ligating enzymes, which reduced polySUMO-conjugate accumulation. The mRNA levels for almost all ribosomal proteins increases transiently upon initial loss of Ulp2, but elevated Ccr4 levels limit excess ribosome formation. Notably, extended passaging leads to increased levels of many small nucleolar RNAs (snoRNAs) involved in ribosome biogenesis, and higher dosage of three linked ChrXII snoRNA genes suppressed ChrXII disomy in ulp2? cells. Our data reveal that aneuploidy allows rapid adaptation to Ulp2 loss, but long-term adaptation restores euploidy. Cellular evolution restores homeostasis through countervailing mutations in SUMO-modification pathways and regulatory shifts in ribosome biogenesis. Overall design: aneuploid ulp2? yeast undergo an analogous evolutionary process using whole genome DNA sequencing (DNA-seq) to identify potential gene mutations arising during repeated cell passaging. WT, ulp2? and ulp2? reintroduced with pULP2 strains that had been passaged for 500 generations.