Medical Research Council Laboratory of Molecular Biology, Cambridge, England, United Kingdom.
Nat Chem Biol. 2010 Oct;6(10):750-7. doi: 10.1038/nchembio.426. Epub 2010 Aug 29.
Ubiquitination is a reversible post-translational modification that regulates a myriad of eukaryotic functions. Our ability to study the effects of ubiquitination is often limited by the inaccessibility of homogeneously ubiquitinated proteins. In particular, elucidating the roles of the so-called 'atypical' ubiquitin chains (chains other than Lys48- or Lys63-linked ubiquitin), which account for a large fraction of ubiquitin polymers, is challenging because the enzymes for their biosynthesis are unknown. Here we combine genetic code expansion, intein chemistry and chemoselective ligations to synthesize 'atypical' ubiquitin chains. We solve the crystal structure of Lys6-linked diubiquitin, which is distinct from that of structurally characterized ubiquitin chains, providing a molecular basis for the different biological functions this linkage may regulate. Moreover, we profile a panel containing 10% of the known human deubiquitinases on Lys6- and Lys29-linked ubiquitin and discover that TRABID cleaves the Lys29 linkage 40-fold more efficiently than the Lys63 linkage.
泛素化是一种可逆的翻译后修饰，可调节真核生物的多种功能。我们研究泛素化影响的能力常常受到均一泛素化蛋白不可及的限制。特别是，阐明所谓的“非典型”泛素链（除 Lys48-或 Lys63 连接的泛素以外的链）的作用具有挑战性，因为它们的生物合成酶尚不清楚。在这里，我们结合遗传密码扩展、内含肽化学和化学选择性连接来合成“非典型”泛素链。我们解决了 Lys6 连接的二泛素的晶体结构，它与结构特征化的泛素链不同，为该连接可能调节的不同生物学功能提供了分子基础。此外，我们对包含已知的 10%人类去泛素化酶的组进行了 Lys6-和 Lys29 连接的泛素分析，发现 TRABID 切割 Lys29 连接的效率比 Lys63 连接高 40 倍。
