PDF(Pubmed)
Abstract：
UFMylation is a highly conserved ubiquitin-like post-translational modification that catalyzes the covalent linkage of UFM1 to its target proteins. This modification plays a critical role in the maintenance of endoplasmic reticulum proteostasis, DNA damage response, autophagy, and transcriptional regulation. Mutations in UFM1, as well as in its specific E1 enzyme UBA5 and E2 enzyme UFC1, have been genetically linked to microcephaly. Our previous research unveiled the important role of UFMylation in regulating mitosis. However, the underlying mechanisms have remained unclear due to the limited identification of substrates. In this study, we identified Eg5, a motor protein crucial for mitotic spindle assembly and maintenance, as a novel substrate for UFMylation and identified Lys564 as the crucial UFMylation site. UFMylation did not alter its transcriptional level, phosphorylation level, or protein stability, but affected the mono-ubiquitination of Eg5. During mitosis, Eg5 and UFM1 co-localize at the centrosome and spindle apparatus, and defective UFMylation leads to diminished spindle localization of Eg5. Notably, the UFMylation-defective Eg5 mutant (K564R) exhibited shorter spindles, metaphase arrest, spindle checkpoint activation, and a failure of cell division in HeLa cells. Overall, Eg5 UFMylation is essential for proper spindle organization, mitotic progression, and cell proliferation.
摘要：
UFMylation是一种高度保守的泛素样翻译后修饰，可催化UFM1与其靶蛋白的共价连接。这种修饰在维持内质网蛋白质稳定中起着关键作用，DNA损伤反应,自噬,和转录调控。UFM1及其特定E1酶UBA5和E2酶UFC1的突变已与小头畸形遗传相关。我们先前的研究揭示了UFMylation在调节有丝分裂中的重要作用。然而,由于底物的鉴定有限,潜在的机制仍不清楚.在这项研究中,我们鉴定了Eg5，一种对有丝分裂纺锤体组装和维持至关重要的运动蛋白，作为UFMylation的新底物，并将Lys564鉴定为关键的UFMylation位点。UFMylation没有改变其转录水平，磷酸化水平，或蛋白质稳定性，但影响了Eg5的单泛素化。在有丝分裂期间，Eg5和UFM1共同定位在中心体和主轴装置上，UFM化缺陷会导致Eg5的纺锤体定位减少。值得注意的是,UFM化缺陷型Eg5突变体（K564R）表现出更短的纺锤体，中期逮捕,主轴检查点激活,和HeLa细胞的细胞分裂失败。总的来说,Eg5UF酰化对于正确的纺锤体组织至关重要，有丝分裂进展，和细胞增殖。
