To maintain protein homeostasis in changing nutrient environments, cells must precisely control the amount of their proteins, despite the accompanying changes in cell growth and biosynthetic capacity. As nutrients are major regulators of cell cycle length and progression, a particular challenge arises for the nutrient-dependent regulation of 'cell cycle genes', which are periodically expressed during the cell cycle. One important example are histones, which are needed at a constant histone-to-DNA stoichiometry. Here we show that budding yeast achieves histone homeostasis in different nutrients through a decoupling of transcript and protein abundance. We find that cells downregulate histone transcripts in poor nutrients to avoid toxic histone overexpression, but produce constant amounts of histone proteins through nutrient-specific regulation of translation efficiency. Our findings suggest that this allows cells to balance the need for rapid histone production under fast growth conditions with the tight regulation required to avoid toxic overexpression in poor nutrients.

中文翻译：

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解耦的转录本和蛋白质浓度确保不同营养物质中的组蛋白稳态。


为了在不断变化的营养环境中维持蛋白质稳态，细胞必须精确控制其蛋白质的量，尽管细胞生长和生物合成能力会发生变化。由于营养物质是细胞周期长度和进程的主要调节因子，因此在细胞周期中周期性表达的“细胞周期基因”的营养依赖性调节出现了一个特殊的挑战。一个重要的例子是组蛋白，在恒定的组蛋白到 DNA 化学计量下需要组蛋白。在这里，我们表明出芽酵母通过转录本和蛋白质丰度的解耦实现不同营养物质中的组蛋白稳态。我们发现细胞在营养不良中下调组蛋白转录物以避免毒性组蛋白过表达，但通过营养特异性调节翻译效率产生恒定数量的组蛋白。我们的研究结果表明，这使得细胞能够在快速生长条件下快速产生组蛋白的需求与避免在不良营养物质中毒性过表达所需的严格调节之间取得平衡。