Structural insights into endosomal sorting complex required for transport (ESCRT-I) recognition of ubiquitinated proteins
Structural insights into endosomal sorting complex required for transport (ESCRT-I) recognition of ubiquitinated proteins
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DOI：
10.1074/jbc.m400023200
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发表时间：
2004-07-02
影响因子：
4.8
通讯作者：
Williams, RL
中科院分区：
文献类型：
--
作者：
Teo, H;Veprintsev, DB;Williams, RL
转运所需的内体分选复合物（ESCRT-I）是由三种蛋白质（Vps 23、Vps 28和Vps 37）组成的350-kDa复合物。Vps 23的N-末端泛素缀合酶E2变体（UEV）结构域是将泛素化蛋白分选到多泡体的内部囊泡中所必需的。UEV与E2泛素连接酶同源，但缺乏催化活性所需的保守半胱氨酸残基。酵母Vps 23 UEV与泛素（Ub）复合物的晶体结构显示了与结合的Ub的详细相互作用。与不存在Ub的Tsg 101 UEV（Vps 23的人类同源物）的溶液结构相比，ESCRT-I UEV中保守的两个环相互移动，以钳状抓住Ub。与UEV的接触包括Ub表面上的两个相邻斑块，一个含有几个疏水残基，包括Ile-8（Ub）、Ile-44（Ub）和瓦尔-70（Ub），第二个含有亲水斑块，包括残基Asn-60（Ub）、Gln-62（Ub）、Glu-64（Ub）。与Vps 23 UEV相互作用的疏水性Ub补丁与Vps 27泛素相互作用基序相互作用的Ub表面重叠，这表明这些蛋白质与泛素化货物结合的顺序模型。相比之下，亲水性贴片包含与ESCRT-I UEV独特相互作用的残基。该结构为突变体的设计提供了详细的框架，所述突变体可以特异性地影响泛素化货物的ESCRT-I依赖性分选，而不影响Vps 27介导的货物向内体的递送。
The endosomal sorting complex required for transport (ESCRT-I) is a 350-kDa complex of three proteins, Vps23, Vps28, and Vps37. The N-terminal ubiquitin-conjugating enzyme E2 variant (UEV) domain of Vps23 is required for sorting ubiquitinated proteins into the internal vesicles of multivesicular bodies. UEVs are homologous to E2 ubiquitin ligases but lack the conserved cysteine residue required for catalytic activity. The crystal structure of the yeast Vps23 UEV in a complex with ubiquitin (Ub) shows the detailed interactions made with the bound Ub. Compared with the solution structure of the Tsg101 UEV ( the human homologue of Vps23) in the absence of Ub, two loops that are conserved among the ESCRT-I UEVs move toward each other to grip the Ub in a pincer-like grasp. The contacts with the UEV encompass two adjacent patches on the surface of the Ub, one containing several hydrophobic residues, including Ile-8(Ub), Ile-44(Ub), and Val-70(Ub), and the second containing a hydrophilic patch including residues Asn-60(Ub), Gln-62(Ub), Glu-64(Ub). The hydrophobic Ub patch interacting with the Vps23 UEV overlaps the surface of Ub interacting with the Vps27 ubiquitin-interacting motif, suggesting a sequential model for ubiquitinated cargo binding by these proteins. In contrast, the hydrophilic patch encompasses residues uniquely interacting with the ESCRT-I UEV. The structure provides a detailed framework for design of mutants that can specifically affect ESCRT-I-dependent sorting of ubiquitinated cargo without affecting Vps27-mediated delivery of cargo to endosomes.