Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands; The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan 430071, China; Medical Research Institute, Wuhan University, Wuhan 430071, China.
Structure. 2019 Sep 3;27(9):1375-1383.e3. doi: 10.1016/j.str.2019.07.002. Epub 2019 Jul 25.
Katanin is a microtubule-severing enzyme that is crucial for many cellular processes. Katanin consists of two subunits, p60 and p80, that form a stable complex. The interaction between subunits is mediated by the p60 N-terminal microtubule-interacting and -trafficking domain (p60-MIT) and the p80 C-terminal domain (p80-CTD). Here, we performed a biophysical characterization of the mouse p60-MIT:p80-CTD heterodimer and show that this complex can assemble into heterotetramers. We identified two mutations that enhance heterotetramer formation and determined the X-ray crystal structure of this mutant complex. The structure revealed a domain-swapped heterotetramer consisting of two p60-MIT:p80-CTD heterodimers. Structure-based sequence alignments suggest that heterotetramerization of katanin might be a common feature of various species. Furthermore, we show that enhanced heterotetramerization of katanin impairs its microtubule end-binding properties and increases the enzyme's microtubule lattice binding and severing activities. Therefore, our findings suggest the existence of different katanin oligomers that possess distinct functional properties.
卡坦丁是一种微管切割酶，对许多细胞过程至关重要。卡坦丁由两个亚基，p60 和 p80 组成，形成一个稳定的复合物。亚基之间的相互作用由 p60 N 端微管相互作用和运输结构域（p60-MIT）和 p80 C 端结构域（p80-CTD）介导。在这里，我们对小鼠 p60-MIT：p80-CTD 异源二聚体进行了生物物理特性分析，表明该复合物可以组装成异源四聚体。我们鉴定了两个增强异源四聚体形成的突变，并确定了该突变复合物的 X 射线晶体结构。该结构揭示了一个由两个 p60-MIT：p80-CTD 异源二聚体组成的结构域交换异源四聚体。基于结构的序列比对表明，卡坦丁的异源四聚化可能是各种物种的共同特征。此外，我们表明，卡坦丁的增强异源四聚化会损害其微管末端结合特性，并增加酶的微管晶格结合和切割活性。因此，我们的发现表明存在具有不同功能特性的不同卡坦丁寡聚体。
