Stuchell-Brereton Melissa D, Skalicky Jack J, Kieffer Collin, Karren Mary Anne, Ghaffarian Sanaz, Sundquist Wesley I
Department of Biochemistry, Room 4100, 15 N. Medical Drive East, University of Utah, Salt Lake City, Utah 84112-5650, USA.
Nature. 2007 Oct 11;449(7163):740-4. doi: 10.1038/nature06172.
The ESCRT (endosomal sorting complex required for transport) pathway is required for terminal membrane fission events in several important biological processes, including endosomal intraluminal vesicle formation, HIV budding and cytokinesis. VPS4 ATPases perform a key function in this pathway by recognizing membrane-associated ESCRT-III assemblies and catalysing their disassembly, possibly in conjunction with membrane fission. Here we show that the microtubule interacting and transport (MIT) domains of human VPS4A and VPS4B bind conserved sequence motifs located at the carboxy termini of the CHMP1-3 class of ESCRT-III proteins. Structures of VPS4A MIT-CHMP1A and VPS4B MIT-CHMP2B complexes reveal that the C-terminal CHMP motif forms an amphipathic helix that binds in a groove between the last two helices of the tetratricopeptide-like repeat (TPR) of the VPS4 MIT domain, but in the opposite orientation to that of a canonical TPR interaction. Distinct pockets in the MIT domain bind three conserved leucine residues of the CHMP motif, and mutations that inhibit these interactions block VPS4 recruitment, impair endosomal protein sorting and relieve dominant-negative VPS4 inhibition of HIV budding. Thus, our studies reveal how the VPS4 ATPases recognize their CHMP substrates to facilitate the membrane fission events required for the release of viruses, endosomal vesicles and daughter cells.
内体分选转运所需复合物(ESCRT)途径在几个重要的生物学过程中对于终末膜裂变事件是必需的,包括内体腔内囊泡形成、HIV出芽和胞质分裂。VPS4 ATP酶在该途径中发挥关键作用,通过识别与膜相关的ESCRT-III组装体并催化其解聚,可能与膜裂变协同作用。在这里,我们表明人类VPS4A和VPS4B的微管相互作用和转运(MIT)结构域结合位于ESCRT-III蛋白CHMP1-3类羧基末端的保守序列基序。VPS4A MIT-CHMP1A和VPS4B MIT-CHMP2B复合物的结构表明,C末端CHMP基序形成一个两亲性螺旋,该螺旋结合在VPS4 MIT结构域四肽重复序列(TPR)最后两个螺旋之间的凹槽中,但方向与典型的TPR相互作用相反。MIT结构域中的不同口袋结合CHMP基序的三个保守亮氨酸残基,抑制这些相互作用的突变会阻止VPS4募集,损害内体蛋白分选,并减轻VPS4对HIV出芽的显性负抑制作用。因此,我们的研究揭示了VPS4 ATP酶如何识别其CHMP底物,以促进病毒、内体囊泡和子细胞释放所需的膜裂变事件。