College of Chemistry, Fuzhou University, Fuzhou 350108, China.
Institute of Molecular Enzymology, School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215000, China.
Structure. 2022 May 5;30(5):743-752.e3. doi: 10.1016/j.str.2022.02.015. Epub 2022 Mar 14.
MUS81 is an important structure-specific endonuclease responsible for the processing of stalled replication forks and recombination intermediates. In human, MUS81 functions by forming complexes with its regulatory subunits EME1 and EME2, playing distinct roles in G2/M and S phases. Although the structures of MUS81-EME1 have been intensively studied, there is no structure information available about MUS81-EME2. Here, we report the crystal structure of MUS81-EME2, which reveals an overall protein fold similar to that of MUS81-EME1 complex. Further biochemical and structural characterization shows that the MUS81-EME1 and MUS81-EME2 complexes are identical in substrate recognition and endonuclease activities in vitro, implying that the distinct cellular roles of the two complexes could arise from temporal controls in cells. Finally, an extensive structure-guided mutagenesis analysis provides implications for the molecular basis of how the MUS81-EME endonucleases recognize various DNA substrates in a structure-selective manner.
MUS81 是一种重要的结构特异性内切酶，负责处理停滞的复制叉和重组中间体。在人类中，MUS81 通过与其调节亚基 EME1 和 EME2 形成复合物发挥作用，在 G2/M 和 S 期发挥不同的作用。尽管已经对 MUS81-EME1 的结构进行了深入研究，但尚无 MUS81-EME2 的结构信息。在这里，我们报告了 MUS81-EME2 的晶体结构，该结构揭示了与 MUS81-EME1 复合物相似的整体蛋白折叠。进一步的生化和结构表征表明，MUS81-EME1 和 MUS81-EME2 复合物在体外具有相同的底物识别和内切酶活性，这表明两个复合物在细胞中的不同细胞作用可能来自于细胞中的时间控制。最后，广泛的结构引导的突变分析为 MUS81-EME 内切酶如何以结构选择性方式识别各种 DNA 底物提供了分子基础的启示。
