Bertolaet B L, Clarke D J, Wolff M, Watson M H, Henze M, Divita G, Reed S I
Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Nat Struct Biol. 2001 May;8(5):417-22. doi: 10.1038/87575.
Rad23 is a highly conserved protein involved in nucleotide excision repair (NER) that associates with the proteasome via its N-terminus. Its C-terminal ubiquitin-associated (UBA) domain is evolutionarily conserved from yeast to humans. However, the cellular function of UBA domains is not completely understood. Recently, RAD23 and DDI1, both DNA damage-inducible genes encoding proteins with UBA domains, were implicated genetically in Pds1-dependent mitotic control in yeast. The UBA domains of RAD23 and DDI1 are required for these interactions. Timely degradation of Pds1 via the ubiquitin/proteasome pathway allows anaphase onset and is crucial for chromosome maintenance. Here, we show that Rad23 and Ddi1 interact directly with ubiquitin and that this interaction is dependent on their UBA domains, providing a possible mechanism for UBA-dependent cell cycle control. Moreover, we show that a hydrophobic surface on the UBA domain, which from structural work had been predicted to be a protein-protein interaction interface, is indeed required for ubiquitin binding. By demonstrating that UBA domains interact with ubiquitin, we have provided the first indication of a cellular function for the UBA domain.
Rad23是一种参与核苷酸切除修复（NER）的高度保守蛋白，它通过其N端与蛋白酶体结合。其C端泛素相关（UBA）结构域从酵母到人类在进化上都是保守的。然而，UBA结构域的细胞功能尚未完全了解。最近，RAD23和DDI1这两个编码具有UBA结构域蛋白的DNA损伤诱导基因，在酵母中被遗传学证明参与Pds1依赖性有丝分裂控制。RAD23和DDI1的UBA结构域对于这些相互作用是必需的。通过泛素/蛋白酶体途径及时降解Pds1可允许后期开始，并且对染色体维持至关重要。在这里，我们表明Rad23和Ddi1直接与泛素相互作用，并且这种相互作用依赖于它们的UBA结构域，这为依赖UBA的细胞周期控制提供了一种可能的机制。此外，我们表明UBA结构域上的一个疏水表面确实是泛素结合所必需的，该表面从结构研究中预测为蛋白质-蛋白质相互作用界面。通过证明UBA结构域与泛素相互作用，我们首次揭示了UBA结构域的细胞功能。
