DNA Replication and Repair

我们已经解决了FAM111A丝氨酸蛋白酶结构域(SPD)的X射线晶体结构。这些结构信息将有助于我们确定调节FAM111A蛋白酶活性的潜在机制。我们的生化和结构研究表明，FAM111ASPD通过N-末端的α-1螺旋形成同源二聚体，在那里两个亚基通过疏水相互作用连接在一起。我们发现，天冬氨酸取代二聚化界面上的缬氨酸，破坏了二聚体的形成，降低了其蛋白酶活性。这些数据表明，酶结构域的二聚化对FAM111a的活性至关重要。我们的体内实验支持了二聚体形成的重要性，我们的体内实验表明，该单体突变体在防止DPC堆积方面存在缺陷，并且未能促进喜树碱诱导的DPC的DNA复制。这些结果提出了一个新的概念，即可以阻止二聚体形成的化学物质可以用作FAM111A的抑制剂。

We have solved X-ray crystal structures of the FAM111A serine protease domain (SPD). The structural information will help us determine potential mechanisms that regulate the protease activity of FAM111A. Our biochemical and structural studies suggested that FAM111A SPD forms a homodimer through the alpha-1 helix at the N-terminus, where two subunits are held together through hydrophobic interactions. We found that substitution of valine on the dimerization interface with aspartate disrupted dimer formation and diminished its protease activity. These data suggest that the dimerization of the enzyme domain is crucial for the activity of FAM111A. Supporting the importance of the dimer formation, our in vivo experiments suggested that the monomeric mutant was defective in preventing DPC accumulation and failed to promote DNA replication at DPCs induced by camptothecin. These results raise a new concept that chemicals that can block dimer formation could be used as an inhibitor of FAM111A.