Department of Microbiology, UMass Chan Medical School, Worcester, Massachusetts, United States of America.
PLoS Genet. 2024 Sep 5;20(9):e1011392. doi: 10.1371/journal.pgen.1011392. eCollection 2024 Sep.
Cytoplasmic poly(A)-binding protein (PABPC; Pab1 in yeast) is thought to be involved in multiple steps of post-transcriptional control, including translation initiation, translation termination, and mRNA decay. To understand both the direct and indirect roles of PABPC in more detail, we have employed mass spectrometry to assess the abundance of the components of the yeast proteome, as well as RNA-Seq and Ribo-Seq to analyze changes in the abundance and translation of the yeast transcriptome, in cells lacking the PAB1 gene. We find that pab1Δ cells manifest drastic changes in the proteome and transcriptome, as well as defects in translation initiation and termination. Defects in translation initiation and the stabilization of specific classes of mRNAs in pab1Δ cells appear to be partly indirect consequences of reduced levels of specific initiation factors, decapping activators, and components of the deadenylation complex in addition to the general loss of Pab1's direct role in these processes. Cells devoid of Pab1 also manifested a nonsense codon readthrough phenotype indicative of a defect in translation termination. Collectively, our results indicate that, unlike the loss of simpler regulatory proteins, elimination of cellular Pab1 is profoundly pleiotropic and disruptive to numerous aspects of post-transcriptional regulation.
细胞质多聚（A）结合蛋白（PABPC；酵母中的 Pab1）被认为参与多个转录后调控步骤，包括翻译起始、翻译终止和 mRNA 降解。为了更详细地了解 PABPC 的直接和间接作用，我们采用质谱法评估了酵母蛋白质组的组成部分的丰度，以及 RNA-Seq 和 Ribo-Seq 来分析缺失 PAB1 基因的细胞中酵母转录组的丰度和翻译的变化。我们发现 pab1Δ 细胞在蛋白质组和转录组中表现出剧烈的变化，以及翻译起始和终止的缺陷。pab1Δ 细胞中翻译起始和特定类别 mRNA 的稳定性的缺陷似乎部分是由于特定起始因子、脱帽激活因子和腺苷酸化复合物的成分水平降低的间接后果，除了 Pab1 在这些过程中的直接作用的普遍丧失之外。缺乏 Pab1 的细胞还表现出无意义密码子通读表型，表明翻译终止存在缺陷。总的来说，我们的结果表明，与简单的调节蛋白的缺失不同，细胞 Pab1 的消除对转录后调控的许多方面都是深远的多效性和破坏性的。
