Azad Kimi, Guilligay Delphine, Boscheron Cecile, Maity Sourav, De Franceschi Nicola, Sulbaran Guidenn, Effantin Gregory, Wang Haiyan, Kleman Jean-Philippe, Bassereau Patricia, Schoehn Guy, Roos Wouter H, Desfosses Ambroise, Weissenhorn Winfried
Institute of Structural Biology (IBS), University Grenoble Alpes, CEA, CNRS, Grenoble, France.
Moleculaire Biofysica, Zernike Institute, Rijksuniversiteit Groningen, Groningen, the Netherlands.
Nat Struct Mol Biol. 2023 Jan;30(1):81-90. doi: 10.1038/s41594-022-00867-8. Epub 2023 Jan 5.
The endosomal sorting complex required for transport (ESCRT) is a highly conserved protein machinery that drives a divers set of physiological and pathological membrane remodeling processes. However, the structural basis of ESCRT-III polymers stabilizing, constricting and cleaving negatively curved membranes is yet unknown. Here we present cryo-EM structures of membrane-coated CHMP2A-CHMP3 filaments from Homo sapiens of two different diameters at 3.3 and 3.6 Å resolution. The structures reveal helical filaments assembled by CHMP2A-CHMP3 heterodimers in the open ESCRT-III conformation, which generates a partially positive charged membrane interaction surface, positions short N-terminal motifs for membrane interaction and the C-terminal VPS4 target sequence toward the tube interior. Inter-filament interactions are electrostatic, which may facilitate filament sliding upon VPS4-mediated polymer remodeling. Fluorescence microscopy as well as high-speed atomic force microscopy imaging corroborate that VPS4 can constrict and cleave CHMP2A-CHMP3 membrane tubes. We therefore conclude that CHMP2A-CHMP3-VPS4 act as a minimal membrane fission machinery.
转运所需的内体分选复合物（ESCRT）是一种高度保守的蛋白质机制，驱动着一系列不同的生理和病理膜重塑过程。然而，ESCRT-III聚合物稳定、收缩和切割负曲率膜的结构基础尚不清楚。在此，我们展示了来自智人的两种不同直径的膜包被CHMP2A-CHMP3细丝的冷冻电镜结构，分辨率分别为3.3 Å和3.6 Å。这些结构揭示了由CHMP2A-CHMP3异二聚体以开放的ESCRT-III构象组装而成的螺旋细丝，该构象产生了一个部分带正电荷的膜相互作用表面，将短的N端基序定位用于膜相互作用，并将C端VPS4靶序列朝向管内部。细丝间的相互作用是静电作用，这可能有助于在VPS4介导的聚合物重塑过程中细丝滑动。荧光显微镜以及高速原子力显微镜成像证实VPS4可以收缩和切割CHMP2A-CHMP3膜管。因此，我们得出结论，CHMP2A-CHMP3-VPS4作为一种最小的膜裂变机制。
