Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland.
Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics Geneva, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland; Department of Biochemistry and Molecular Biology, Faculty of Science and Informatics, University of Szeged, 6726 Szeged, Hungary.
Cell Rep. 2021 Aug 31;36(9):109633. doi: 10.1016/j.celrep.2021.109633.
In this work, we show that Not4 and Not5 from the Ccr4-Not complex modulate translation elongation dynamics and change ribosome A-site dwelling occupancy in a codon-dependent fashion. These codon-specific changes in not5Δ cells are very robust and independent of codon position within the mRNA, the overall mRNA codon composition, or changes of mRNA expression levels. They inversely correlate with codon-specific changes in cells depleted for eIF5A and positively correlate with those in cells depleted for ribosome-recycling factor Rli1. Not5 resides in punctate loci, co-purifies with ribosomes and Rli1, but not with eIF5A, and limits mRNA solubility. Overexpression of wild-type or non-complementing Rli1 and loss of Rps7A ubiquitination enable Not4 E3 ligase-dependent translation of polyarginine stretches. We propose that Not4 and Not5 modulate translation elongation dynamics to produce a soluble proteome by Rps7A ubiquitination, dynamic condensates that limit mRNA solubility and exclude eIF5A, and a moonlighting function of Rli1.
在这项工作中，我们表明 Ccr4-Not 复合物中的 Not4 和 Not5 调节翻译延伸动态，并以依赖于密码子的方式改变核糖体 A 位占据。在 not5Δ 细胞中，这些密码子特异性的变化非常稳健，不依赖于 mRNA 中的密码子位置、mRNA 的整体密码子组成或 mRNA 表达水平的变化。它们与 eIF5A 耗尽细胞中的密码子特异性变化呈负相关，与核糖体回收因子 Rli1 耗尽细胞中的密码子特异性变化呈正相关。Not5 位于点状位置，与核糖体和 Rli1 共纯化，但不与 eIF5A 共纯化，并且限制 mRNA 的可溶性。野生型或非互补 Rli1 的过表达和 Rps7A 泛素化的丧失使 Not4 E3 连接酶能够依赖翻译多精氨酸链。我们提出，Not4 和 Not5 通过 Rps7A 泛素化来调节翻译延伸动态，产生一个可溶性的蛋白质组，通过动态凝聚物限制 mRNA 的可溶性并排除 eIF5A，以及 Rli1 的兼职功能。
