Chase Anna R, Laudermilch Ethan, Wang Jimin, Shigematsu Hideki, Yokoyama Takeshi, Schlieker Christian
Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520.
RIKEN Center for Life Science Technologies, Yokohama 230-0045, Japan.
Mol Biol Cell. 2017 Oct 15;28(21):2765-2772. doi: 10.1091/mbc.E17-05-0281. Epub 2017 Aug 16.
TorsinA is an essential AAA+ ATPase requiring LAP1 or LULL1 as cofactors. The dynamics of the Torsin/cofactor system remain poorly understood, with previous models invoking Torsin/cofactor assemblies with fixed stoichiometries. Here we demonstrate that TorsinA assembles into homotypic oligomers in the presence of ATP. Torsin variants mutated at the "back" interface disrupt homo-oligomerization but still show robust ATPase activity in the presence of its cofactors. These Torsin mutants are severely compromised in their ability to rescue nuclear envelope defects in Torsin-deficient cells, suggesting that TorsinA homo-oligomers play a key role in vivo. Engagement of the oligomer by LAP1 triggers ATP hydrolysis and rapid complex disassembly. Thus the Torsin complex is a highly dynamic assembly whose oligomeric state is tightly controlled by distinctively localized cellular cofactors. Our discovery that LAP1 serves as a modulator of the oligomeric state of an AAA+ protein establishes a novel means of regulating this important class of oligomeric ATPases.
TorsinA是一种必需的AAA+ ATP酶，需要LAP1或LULL1作为辅助因子。Torsin/辅助因子系统的动力学仍知之甚少，以前的模型认为Torsin/辅助因子组装具有固定的化学计量。在这里，我们证明TorsinA在ATP存在下组装成同型寡聚体。在“背面”界面发生突变的Torsin变体破坏了同源寡聚化，但在其辅助因子存在下仍表现出强大的ATP酶活性。这些Torsin突变体在挽救Torsin缺陷细胞中的核膜缺陷的能力上严重受损，这表明TorsinA同型寡聚体在体内起关键作用。LAP1与寡聚体的结合触发ATP水解并使复合物迅速解离。因此，Torsin复合物是一种高度动态的组装体，其寡聚状态受到独特定位的细胞辅助因子的严格控制。我们发现LAP1作为一种AAA+蛋白寡聚状态的调节剂，建立了一种调节这一重要类别的寡聚ATP酶的新方法。
