State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, China.
Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, TX, 75080, USA.
Sci Rep. 2017 Jun 16;7(1):3696. doi: 10.1038/s41598-017-03768-9.
Myelin-gene Regulatory Factor (MyRF) is one of the master transcription factors controlling myelin formation and development in oligodendrocytes which is crucial for the powerful brain functions. The N-terminal of MyRF, which contains a proline-rich region and a DNA binding domain (DBD), is auto-cleaved from the ER membrane, and then enters the nucleus to participate in transcription regulation of the myelin genes. Here we report the crystal structure of MyRF DBD. It shows an Ig-fold like architecture which consists of two antiparallel β-sheets with 7 main strands, packing against each other, forming a β-sandwich. Compared to its homolog, Ndt80, MyRF has a smaller and less complex DBD lacking the helices and the big loops outside the core. Structural alignment reveals that MyRF DBD possess less interaction sites with DNA than Ndt80 and may bind only at the major groove of DNA. Moreover, the structure reveals a trimeric assembly, agreeing with the previous report that MyRF DBD functions as a trimer. The mutant that we designed based on the structure disturbed trimer formation, but didn't affect the auto-cleavage reaction. It demonstrates that the activation of self-cleavage reaction of MyRF is independent of the presence of its N-terminal DBD homotrimer. The structure reported here will help to understand the molecular mechanism underlying the important roles of MyRF in myelin formation and development.
髓鞘基因调控因子（MyRF）是控制少突胶质细胞髓鞘形成和发育的主要转录因子之一，对大脑的强大功能至关重要。MyRF 的 N 端包含一个富含脯氨酸的区域和一个 DNA 结合域（DBD），从内质网膜上自动切割下来，然后进入细胞核，参与髓鞘基因的转录调控。我们在此报告了 MyRF DBD 的晶体结构。它呈现出 Ig 折叠样结构，由两个反平行的β-折叠组成，包含 7 条主要链，彼此交错排列，形成β-三明治结构。与同源物 Ndt80 相比，MyRF 的 DBD 更小且更简单，缺乏核心以外的螺旋和大环。结构比对表明，MyRF DBD 与 DNA 的相互作用位点比 Ndt80 少，可能仅结合在 DNA 的大沟中。此外，该结构揭示了三聚体组装，与之前报道的 MyRF DBD 作为三聚体发挥作用的结果一致。我们基于结构设计的突变体扰乱了三聚体的形成，但不影响自身切割反应。这表明 MyRF 自我切割反应的激活不依赖于其 N 端 DBD 同源三聚体的存在。这里报道的结构将有助于理解 MyRF 在髓鞘形成和发育中发挥重要作用的分子机制。
