Complete cytoplasmic polyadenosine tail (polyA-tail) deadenylation is thought to be essential for initiating mRNA decapping and subsequent degradation. To investigate this prevalent model, we conducted direct RNA sequencing of S. cerevisiae mRNAs derived from chase experiments under steady-state and stress condition. Subsequently, we developed a numerical model based on a modified gamma distribution function, which estimated the transcriptomic deadenylation rate at 10 A/min. A simplified independent method, based on the delineation of quantile polyA-tail values, showed a correlation between the decay and deadenylation rates of individual mRNAs, which appeared consistent within functional transcript groups and associated with codon optimality. Notably, these rates varied during the stress response. Detailed analysis of ribosomal protein-coding mRNAs (RPG mRNAs), constituting 40% of the transcriptome, singled out this transcript group. While deadenylation and decay of RPG mRNAs accelerated under heat stress, their degradation could proceed even when deadenylation was blocked, depending entirely on ongoing nuclear export. Our findings support the general primary function of deadenylation in dictating the onset of decapping, while also demonstrating complex relations between these processes.

中文翻译：

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mRNA 脱腺苷化速率的建模揭示了 mRNA 脱腺苷化和衰变之间的复杂关系。


完全细胞质多聚腺苷尾 （polyA 尾） 脱腺苷化被认为对于启动 mRNA 脱帽和随后的降解至关重要。为了研究这种普遍的模型，我们对稳态和应激条件下来自追逐实验的酿酒酵母 mRNAs 进行了直接 RNA 测序。随后，我们开发了一个基于修改后的 γ 分布函数的数值模型，该模型估计转录组脱腺苷化速率为 10 A/min。一种基于分位数 polyA 尾值描述的简化独立方法显示了单个 mRNA 的衰变和脱腺苷化速率之间的相关性，这在功能转录组内似乎是一致的，并且与密码子最优性相关。值得注意的是，这些速率在应激反应期间发生了变化。对占转录组 40% 的核糖体蛋白编码 mRNA （RPG mRNA） 的详细分析中，挑选出了该转录组。虽然 RPG mRNA 的脱腺苷化和衰变在热应激下加速，但即使脱腺苷化被阻断，它们的降解也可以继续进行，这完全取决于持续的核输出。我们的研究结果支持脱腺苷化在决定脱帽开始方面的一般主要功能，同时也证明了这些过程之间的复杂关系。