From the Center for Cell and Genome Science and Department of Biology, University of Utah, Salt Lake City, Utah 84112 and.
J Biol Chem. 2013 Sep 13;288(37):26810-9. doi: 10.1074/jbc.M113.497032. Epub 2013 Aug 2.
The AAA-type ATPase Vps4 functions with components of the ESCRT (endosomal sorting complex required for transport) machinery in membrane fission events that are essential for endosomal maturation, cytokinesis, and the formation of retroviruses. A key step in these events is the assembly of monomeric Vps4 into the active ATPase complex, which is aided in part by binding of Vps4 via its N-terminal MIT (microtubule interacting and trafficking) domain to its substrate ESCRT-III. We found that the 40-amino acid linker region between the MIT and the ATPase domain of Vps4 is not required for proper function but plays a role in regulating Vps4 assembly and ATPase activity. Deletion of the linker is expected to bring the MIT domains into close proximity to the central pore of the Vps4 complex. We propose that this localization of the MIT domain in linker-deleted Vps4 mimics a repositioning of the MIT domain normally caused by binding of Vps4 to ESCRT-III. This structure would allow the Vps4 complex to engage ESCRT-III subunits with both the pore and the MIT domain simultaneously, which might be essential for the ATP-driven disassembly of ESCRT-III.
AAA 型 ATP 酶 Vps4 与内体分选复合物（endosomal sorting complex required for transport，ESCRT）机器的组件一起在膜裂变事件中发挥作用，这些事件对于内体成熟、胞质分裂和逆转录病毒的形成是必不可少的。这些事件中的一个关键步骤是将单体 Vps4 组装成活性 ATP 酶复合物，这部分通过 Vps4 通过其 N 端 MIT（微管相互作用和运输）结构域与底物 ESCRT-III 的结合来辅助。我们发现，Vps4 的 MIT 结构域和 ATP 酶结构域之间的 40 个氨基酸连接区对于正常功能不是必需的，但在调节 Vps4 组装和 ATP 酶活性方面发挥作用。预计删除连接区会使 MIT 结构域紧密接近 Vps4 复合物的中央孔。我们提出，在连接区缺失的 Vps4 中，MIT 结构域的这种定位模拟了由于 Vps4 与 ESCRT-III 的结合而导致的 MIT 结构域的重新定位。这种结构可能允许 Vps4 复合物同时与孔和 MIT 结构域结合 ESCRT-III 亚基，这对于 ATP 驱动的 ESCRT-III 解体可能是必不可少的。
