Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
Department of Biochemistry, University of Geneva, Geneva CH-1211, Switzerland.
J Cell Sci. 2020 Apr 28;133(8):jcs241455. doi: 10.1242/jcs.241455.
The ESCRT-III protein complex executes reverse-topology membrane scission. The scission mechanism is unclear but is linked to remodeling of ESCRT-III complexes at the membrane surface. At endosomes, ESCRT-III mediates the budding of intralumenal vesicles (ILVs). In , ESCRT-III activity at endosomes is regulated through an unknown mechanism by Doa4, an ubiquitin hydrolase that deubiquitylates transmembrane proteins sorted into ILVs. We report that the non-catalytic N-terminus of Doa4 binds Snf7, the predominant ESCRT-III subunit. Through this interaction, Doa4 overexpression alters Snf7 assembly status and inhibits ILV membrane scission. , the Doa4 N-terminus inhibits association of Snf7 with Vps2, which functions with Vps24 to arrest Snf7 polymerization and remodel Snf7 polymer structure. , Doa4 overexpression inhibits Snf7 interaction with Vps2 and also with the ATPase Vps4, which is recruited by Vps2 and Vps24 to remodel ESCRT-III complexes by catalyzing subunit turnover. Our data suggest a mechanism by which the deubiquitylation machinery regulates ILV biogenesis by interfering with ESCRT-III remodeling.
ESCRT-III 蛋白复合物执行逆拓扑膜分裂。分裂机制尚不清楚，但与 ESCRT-III 复合物在膜表面的重塑有关。在内体中，ESCRT-III 介导腔内囊泡（ILV）的出芽。在 ，ESCRT-III 的活性通过一种未知的机制受到 Doa4 的调节，Doa4 是一种泛素水解酶，可将分选到 ILVs 中的跨膜蛋白去泛素化。我们报告说，Doa4 的非催化 N 端与 Snf7 结合，Snf7 是主要的 ESCRT-III 亚基。通过这种相互作用，Doa4 的过表达改变了 Snf7 的组装状态并抑制了 ILV 膜的分裂。 ，Doa4 的 N 端抑制了 Snf7 与 Vps2 的结合，Vps2 与 Vps24 一起作用以阻止 Snf7 聚合并重塑 Snf7 聚合物结构。 ，Doa4 的过表达抑制了 Snf7 与 Vps2 和 ATP 酶 Vps4 的相互作用，Vps4 被 Vps2 和 Vps24 募集，通过催化亚基周转来重塑 ESCRT-III 复合物。我们的数据表明，去泛素化机制通过干扰 ESCRT-III 重塑来调节 ILV 生物发生的一种机制。
