The role of proteins often changes during evolution, but we do not know how cells adapt when a protein is asked to participate in a different biological function. We forced the budding yeast, Saccharomyces cerevisiae, to use the meiosis-specific kleisin, recombination 8 (Rec8), during the mitotic cell cycle, instead of its paralog, Scc1. This perturbation impairs sister chromosome linkage, advances the timing of genome replication, and reduces reproductive fitness by 45%. We evolved 15 parallel populations for 1,750 generations, substantially increasing their fitness, and analyzed the genotypes and phenotypes of the evolved cells. Only one population contained a mutation in Rec8, but many populations had mutations in the transcriptional mediator complex, cohesin-related genes, and cell cycle regulators that induce S phase. These mutations improve sister chromosome cohesion and delay genome replication in Rec8-expressing cells. We conclude that changes in known and novel partners allow cells to use an existing protein to participate in new biological functions.

中文翻译：

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进化修复：多个功能模块的变化允许减数分裂 cohesin 支持有丝分裂。

蛋白质的作用在进化过程中经常发生变化，但我们不知道当蛋白质被要求参与不同的生物功能时细胞如何适应。我们强迫萌芽酵母酿酒酵母在有丝分裂细胞周期期间使用减数分裂特异性 kleisin 重组 8 (Rec8)，而不是其旁系同源物 Scc1。这种扰动会损害姐妹染色体连锁，加快基因组复制的时间，并使生殖适应性降低 45%。我们进化了 1750 代的 15 个平行种群，大大提高了它们的适应性，并分析了进化细胞的基因型和表型。只有一个种群在 Rec8 中包含突变，但许多种群在转录介质复合物、cohesin 相关基因和诱导 S 期的细胞周期调节因子中存在突变。这些突变提高了姐妹染色体的凝聚力并延迟了表达 Rec8 的细胞中的基因组复制。我们得出结论，已知和新伙伴的变化允许细胞使用现有蛋白质来参与新的生物学功能。