Departments of Biology and Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstr. 10, 78457, Konstanz, Germany.
Chembiochem. 2022 Mar 18;23(6):e202100659. doi: 10.1002/cbic.202100659. Epub 2022 Feb 3.
The tumor suppressor p53 is regulated by various posttranslational modifications including different types of ubiquitylation, which exert distinct effects on p53. While modification by ubiquitin chains targets p53 for degradation, attachment of single ubiquitin moieties (mono-ubiquitylation) affects the intracellular location of p53 and/or its interaction with chromatin. However, how this is achieved at the molecular level remains largely unknown. Similarly, since p53 can be ubiquitylated at different lysine residues, it remains unclear if the eventual effect depends on the position of the lysine modified. Here, we combined genetic code expansion with oxime ligation to generate p53 site-specifically mono-ubiquitylated at position 120. We found that mono-ubiquitylation at this position neither interferes with p53 ubiquitylation by the E3 ligases HDM2 and E6AP in complex with the viral E6 oncoprotein nor affects p53 binding to a cognate DNA sequence. Thus, ubiquitylation per se does not affect physiologically relevant properties of p53.
肿瘤抑制因子 p53 受到各种翻译后修饰的调节，包括不同类型的泛素化修饰，这些修饰对 p53 产生不同的影响。虽然泛素链的修饰将 p53 靶向降解，但单个泛素分子的附着（单泛素化）会影响 p53 的细胞内位置和/或其与染色质的相互作用。然而，在分子水平上如何实现这一点在很大程度上仍然未知。同样，由于 p53 可以在不同的赖氨酸残基上被泛素化，因此尚不清楚最终的效果是否取决于修饰的赖氨酸的位置。在这里，我们将遗传密码扩展与肟连接相结合，在第 120 位生成 p53 位置特异性单泛素化。我们发现，该位置的单泛素化既不干扰与病毒 E6 癌蛋白复合的 E3 连接酶 HDM2 和 E6AP 对 p53 的泛素化，也不影响 p53 与同源 DNA 序列的结合。因此，泛素化本身不会影响 p53 的生理相关特性。
