MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, UK.
MRCPPU Reagents and Services, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, UK.
Sci Adv. 2024 Mar 29;10(13):eadh0123. doi: 10.1126/sciadv.adh0123. Epub 2024 Mar 27.
E2-conjugating enzymes (E2s) play a central role in the enzymatic cascade that leads to the attachment of ubiquitin to a substrate. This process, termed ubiquitylation, is required to maintain cellular homeostasis and affects almost all cellular process. By interacting with multiple E3 ligases, E2s dictate the ubiquitylation landscape within the cell. Since its discovery, ubiquitylation has been regarded as a posttranslational modification that specifically targets lysine side chains (canonical ubiquitylation). We used Matrix-Assisted Laser Desorption/Ionization-Time Of Flight Mass Spectrometry to identify and characterize a family of E2s that are instead able to conjugate ubiquitin to serine and/or threonine. We used structural modeling and prediction tools to identify the key activity determinants that these E2s use to interact with ubiquitin as well as their substrates. Our results unveil the missing E2s necessary for noncanonical ubiquitylation, underscoring the adaptability and versatility of ubiquitin modifications.
E2 连接酶 (E2s) 在导致泛素与底物结合的酶级联反应中发挥核心作用。这一过程称为泛素化，对于维持细胞内稳态至关重要，几乎影响所有细胞过程。E2s 通过与多种 E3 连接酶相互作用，决定了细胞内的泛素化景观。自发现以来，泛素化一直被认为是一种专门针对赖氨酸侧链的翻译后修饰（典型泛素化）。我们使用基质辅助激光解吸/电离飞行时间质谱来鉴定和表征一系列相反的 E2s，它们能够将泛素连接到丝氨酸和/或苏氨酸上。我们使用结构建模和预测工具来鉴定这些 E2s 与泛素及其底物相互作用所使用的关键活性决定因素。我们的研究结果揭示了非典型泛素化所需的缺失 E2s，突出了泛素修饰的适应性和多功能性。
