Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
FASEB J. 2018 May;32(5):2794-2802. doi: 10.1096/fj.201701057R. Epub 2018 Jan 8.
All ubiquitin-like proteins (UBLs) undergo an activation process before their conjugation to target proteins. Although the steps required for the activation of UBLs are conserved and common to all UBLs, we have previously shown that the activation of the UBL, ubiquitin fold modifier 1 (UFM1) by the E1, Ufm1 modifier-activating enzyme 5 (UBA5) is executed in a trans-binding mechanism, not observed in any other E1. In this study, we explored the necessity of that mechanism for UFM1 activation and found that it is needed not only for UFM1 binding to UBA5 but also for stabilizing the UBA5 homodimer. Although UBA5 functions as a dimer, in solution it behaves as a weak dimer. Dimerization of UBA5 is required for ATP binding; therefore, stabilization of the dimer by UFM1 enhances ATP binding. Our results make a connection between the binding of UFM1 to UBA5 and the latter's affinity to ATP, so we propose a novel mechanism for the regulation of ATP's binding to E1.-Mashahreh, B., Hassouna, F., Soudah, N., Cohen-Kfir, E., Strulovich, R., Haitin, Y., Wiener, R. Trans-binding of UFM1 to UBA5 stimulates UBA5 homodimerization and ATP binding.
所有泛素样蛋白 (UBL) 在与靶蛋白缀合之前都要经历一个激活过程。尽管UBL 激活所需的步骤是保守的，并且对所有 UBL 都是共同的，但我们之前已经表明，UBL，泛素折叠修饰蛋白 1 (UFM1) 被 E1，Ufm1 修饰酶激活酶 5 (UBA5) 的激活是在一个转结合机制中执行的，在任何其他 E1 中都没有观察到。在这项研究中，我们探讨了该机制对 UFM1 激活的必要性，发现它不仅需要 UFM1 与 UBA5 结合，还需要稳定 UBA5 同源二聚体。尽管 UBA5 作为二聚体发挥作用，但在溶液中它表现为弱二聚体。UBA5 的二聚化对于 ATP 结合是必需的；因此，UFM1 稳定二聚体增强了 ATP 结合。我们的结果将 UFM1 与 UBA5 的结合与后者对 ATP 的亲和力联系起来，因此我们提出了一种新的机制来调节 E1 对 ATP 的结合。-Mashahreh，B.，Hassouna，F.，Soudah，N.，Cohen-Kfir，E.，Strulovich，R.，Haitin，Y.，Wiener，R. UFM1 与 UBA5 的转结合刺激 UBA5 同源二聚化和 ATP 结合。
