Department of Biotechnology, Pondicherry University, Puducherry 605 014, India.
Interdisciplinary Biology, Rajiv Gandhi Centre for Biotechnology, Trivandrum 695 014, India.
Biochim Biophys Acta Mol Cell Res. 2020 Feb;1867(2):118611. doi: 10.1016/j.bbamcr.2019.118611. Epub 2019 Nov 19.
Methylation of proteins is emerging to be an important regulator of protein function. SET7/9, a protein lysine methyltransferase, catalyses methylation of several proteins involved in diverse biological processes. SET7/9-mediated methylation often regulates the stability, sub-cellular localization and protein-protein interactions of its substrate proteins. Here, we aimed to identify novel biological processes regulated by SET7/9 by identifying new interaction partners. For this we used yeast two-hybrid screening and identified the large subunit ribosomal protein, eL42 as a potential interactor of SET7/9. We confirmed the SET7/9-eL42 interaction by co-immunoprecipitation and GST pulldown studies. The N-terminal MORN domain of SET7/9 is essential for its interaction with eL42. Importantly, we identified that SET7/9 methylates eL42 at three different lysines - Lys53, Lys80 and Lys100 through site-directed mutagenesis. By puromycin incorporation assay, we find that SET7/9-mediated methylation of eL42 affects global translation. This study identifies a new role of the functionally versatile SET7/9 lysine methyltransferase in the regulation of global protein synthesis.
蛋白质甲基化正成为蛋白质功能的一个重要调节因子。SET7/9 是一种蛋白赖氨酸甲基转移酶，能够催化多种参与不同生物学过程的蛋白质的甲基化。SET7/9 介导的甲基化通常调节其底物蛋白的稳定性、亚细胞定位和蛋白-蛋白相互作用。在这里，我们旨在通过鉴定新的相互作用伙伴来确定 SET7/9 调节的新的生物学过程。为此，我们使用酵母双杂交筛选并鉴定出大亚基核糖体蛋白 eL42 是 SET7/9 的一个潜在相互作用蛋白。我们通过共免疫沉淀和 GST 下拉研究证实了 SET7/9-eL42 的相互作用。SET7/9 的 MORN 结构域的 N 端对于其与 eL42 的相互作用是必需的。重要的是，我们通过定点突变鉴定出 SET7/9 在三个不同的赖氨酸（Lys53、Lys80 和 Lys100）上对 eL42 进行甲基化。通过嘌呤霉素掺入测定，我们发现 SET7/9 介导的 eL42 甲基化影响全局翻译。这项研究确定了功能多样的 SET7/9 赖氨酸甲基转移酶在调节全局蛋白质合成中的一个新作用。
