The SOCS box domain of SOCS3: Structure and interaction with the elonginBC-cullin5 ubiquitin ligase
The SOCS box domain of SOCS3: Structure and interaction with the elonginBC-cullin5 ubiquitin ligase
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DOI：
10.1016/j.jmb.2008.06.038
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发表时间：
2008-09-12
影响因子：
5.6
通讯作者：
Norton, Raymond S.
中科院分区：
文献类型：
--
作者：
Babon, Jeffrey J.;Sabo, Jennifer K.;Norton, Raymond S.
细胞因子信号转导抑制因子3(SOCS3)负责调节细胞对多种细胞因子的反应，包括白介素6和白血病抑制因子。SOCS盒结构域的鉴定导致了一种假设，即SOCS3可以与功能性E3泛素连接酶结合，从而诱导结合信号蛋白的降解。这个模型依赖于SoCS盒、细长蛋白BC和形成E3连接酶支架的cullin蛋白之间的相互作用。我们利用纯化的组分在体外研究了这种相互作用，结果表明SOCS3以高亲和力与细长蛋白BC和culin5结合。通过确定SOCS盒-LENGINBC三元复合体的溶液结构以及SOCS盒的缺失和丙氨酸扫描突变，进一步表征了SOCS3与LENGINBC的相互作用。这些研究表明，构象灵活性是SOCS-细长蛋白BC相互作用的一个关键特征。特别是，SOCS盒是孤立无序的，并且仅在细长BC关联时才变得结构化。这种相互作用依赖于SOCS盒结构域的前12个残基，特别是一个深埋的、保守的亮氨酸。当SOCS盒与细长蛋白BC结合时，以100 nM的亲和力与culin5紧密结合。SOCS盒上游的结构域不需要与长蛋白BC或cullin5结合，表明SOCS盒作为一个独立的结合域能够募集长蛋白BC和cullin5来促进E3连接酶的形成。(C)2008爱思唯尔有限公司。保留所有权利。
Suppressor of cytokine signalling 3 (SOCS3) is responsible for regulating the cellular response to a variety of cytokines, including interleukin 6 and leukaemia inhibitory factor. Identification of the SOCS box domain led to the hypothesis that SOCS3 can associate with functional E3 ubiquitin ligases and thereby induce the degradation of bound signalling proteins. This model relies upon an interaction between the SOCS box, elonginBC and a cullin protein that forms the E3 ligase scaffold. We have investigated this interaction in vitro using purified components and show that SOCS3 binds to elonginBC and cullin5 with high affinity. The SOCS3-elonginBC interaction was further characterised by determining the solution structure of the SOCS box-elonginBC ternary complex and by deletion and alanine scanning mutagenesis of the SOCS box. These studies revealed that conformational flexibility is a key feature of the SOCS-elonginBC interaction. In particular, the SOCS box is disordered in isolation and only becomes structured upon elonginBC association. The interaction depends upon the first 12 residues of the SOCS box domain and particularly on a deeply buried, conserved leucine. The SOCS box, when bound to elonginBC, binds tightly to cullin5 with 100 nM affinity. Domains upstream of the SOCS box are not required for elonginBC or cullin5 association, indicating that the SOCS box acts as an independent binding domain capable of recruiting elonginBC and cullin5 to promote E3 ligase formation. (C) 2008 Elsevier Ltd. All rights reserved.