A dual role for K63-linked ubiquitin chains in multivesicular body biogenesis and cargo sorting.
A dual role for K63-linked ubiquitin chains in multivesicular body biogenesis and cargo sorting.
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DOI：
10.1091/mbc.e11-10-0891
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发表时间：
2012-06
影响因子：
3.3
通讯作者：
Haguenauer-Tsapis R
中科院分区：
文献类型：
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作者：
Erpapazoglou Z;Dhaoui M;Pantazopoulou M;Giordano F;Mari M;Léon S;Raposo G;Reggiori F;Haguenauer-Tsapis R
许多酵母和一些哺乳动物的多囊体(MVB)货物表现出K63连接的泛素链(K63Ub)的修饰，这是它们有效分选所必需的。酵母中含有UBD的ESCRT蛋白被泛素连接酶Rsp5修饰，其中一些可能被K63Ub修饰。在酵母中不能产生K63Ub会导致MVB超微结构的改变。在酵母中，跨膜蛋白被分选到多泡小体(MVB)内部小泡中，需要泛素连接酶Rsp5将其泛素化。这使得它们能够被泛素结合域(UBD)识别为运输所需的几个内体分选复合体(ESCRT)亚单位。K63连接的泛素(K63Ub)链装饰了几个MVB货物，相应地，我们表明它们显著定位于E类隔室，在缺乏ESCRT成分的细胞中积累泛素化的货物。相反，不能产生K63Ub链的酵母细胞表现出MVB分选缺陷。这些特性在真核生物中是保守的，因为哺乳动物黑素体MVB Cargo Mart-1被K63Ub链修饰，当这些链的发生被抑制时，部分错序。我们发现所有含有酵母UBD的ESCRT蛋白都经历了泛素化和去泛素化，其中一些蛋白通过Rsp5和泛素异肽酶Ubp2的相反活性进行修饰，这两种酶分别优先组装和拆解K63Ub链。在酵母中不能产生K63Ub链会导致MVB超微结构的改变。因此，我们的工作揭示了K63Ub链在货物分拣和MVB生物发生中的双重功能。
Many yeast and some mammalian multivesicular body (MVB) cargoes display modification by K63-linked ubiquitin chains (K63Ub), which are required for their efficient sorting. Yeast UBD-containing ESCRT proteins are modified by the ubiquitin ligase Rsp5—some likely by K63Ub. A failure to generate K63Ub in yeast leads to MVB ultrastructure alteration. In yeast, the sorting of transmembrane proteins into the multivesicular body (MVB) internal vesicles requires their ubiquitylation by the ubiquitin ligase Rsp5. This allows their recognition by the ubiquitin-binding domains (UBDs) of several endosomal sorting complex required for transport (ESCRT) subunits. K63-linked ubiquitin (K63Ub) chains decorate several MVB cargoes, and accordingly we show that they localize prominently to the class E compartment, which accumulates ubiquitylated cargoes in cells lacking ESCRT components. Conversely, yeast cells unable to generate K63Ub chains displayed MVB sorting defects. These properties are conserved among eukaryotes, as the mammalian melanosomal MVB cargo MART-1 is modified by K63Ub chains and partly missorted when the genesis of these chains is inhibited. We show that all yeast UBD-containing ESCRT proteins undergo ubiquitylation and deubiquitylation, some being modified through the opposing activities of Rsp5 and the ubiquitin isopeptidase Ubp2, which are known to assemble and disassemble preferentially K63Ub chains, respectively. A failure to generate K63Ub chains in yeast leads to an MVB ultrastructure alteration. Our work thus unravels a double function of K63Ub chains in cargo sorting and MVB biogenesis.