Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany.
Cells. 2019 Nov 4;8(11):1384. doi: 10.3390/cells8111384.
Diverse signals and stress factors regulate the activity and homeostasis of ribosomes in all cells. The protein Asc1/yRACK1 occupies an exposed site at the head region of the 40S ribosomal subunit () and represents a central hub for signaling pathways. Asc1 strongly affects protein phosphorylation and is involved in quality control pathways induced by translation elongation arrest. Therefore, it is important to understand the dynamics of protein formations in the Asc1 microenvironment at the . We made use of the in vivo protein-proximity labeling technique Biotin IDentification (BioID). Unbiased proxiOMICs from two adjacent perspectives identified nucleocytoplasmic shuttling mRNA-binding proteins, the deubiquitinase complex Ubp3-Bre5, as well as the ubiquitin E3 ligase Hel2 as neighbors of Asc1. We observed Asc1-dependency of localization of mRNA-binding proteins and the Ubp3 co-factor Bre5. Hel2 and Ubp3-Bre5 are described to balance the mono-ubiquitination of Rps3 (uS3) during ribosome quality control. Here, we show that the absence of Asc1 resulted in massive exposure and accessibility of the C-terminal tail of its ribosomal neighbor Rps3 (uS3). Asc1 and some of its direct neighbors together might form a ribosomal decision tree that is tightly connected to close-by signaling modules.
多种信号和应激因素调节所有细胞中核糖体的活性和动态平衡。蛋白 Asc1/yRACK1 占据 40S 核糖体亚基头部区域的一个暴露位点（），是信号通路的中心枢纽。Asc1 强烈影响蛋白质磷酸化，并参与由翻译延伸受阻诱导的质量控制途径。因此，了解 Asc1 微环境中蛋白质形成的动力学是很重要的。我们利用体内蛋白质邻近标记技术 Biotin IDentification (BioID)。来自两个相邻视角的无偏 proxiOMICS 鉴定了核质穿梭的 mRNA 结合蛋白、去泛素化酶复合物 Ubp3-Bre5 以及泛素 E3 连接酶 Hel2 作为 Asc1 的邻居。我们观察到 Asc1 依赖于 mRNA 结合蛋白和 Ubp3 共因子 Bre5 的定位。Hel2 和 Ubp3-Bre5 被描述为在核糖体质量控制过程中平衡 Rps3（uS3）的单泛素化。在这里，我们表明 Asc1 的缺失导致其核糖体邻居 Rps3（uS3）的 C 末端尾巴大量暴露和可及。Asc1 和它的一些直接邻居可能一起形成一个与附近信号模块紧密相连的核糖体决策树。
