Crystal structure of the regulatory subunit of archaeal initiation factor 2B (aIF2B) from hyperthermophilic archaeon Pyrococcus horikoshii OT3:: a proposed structure of the regulatory subcomplex of eukaryotic IF2B
Crystal structure of the regulatory subunit of archaeal initiation factor 2B (aIF2B) from hyperthermophilic archaeon Pyrococcus horikoshii OT3:: a proposed structure of the regulatory subcomplex of eukaryotic IF2B
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DOI：
10.1016/j.bbrc.2004.05.045
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发表时间：
2004-07-02
影响因子：
3.1
通讯作者：
Kimura, M
中科院分区：
文献类型：
--
作者：
Kakuta, Y;Tahara, M;Kimura, M
真核生物翻译起始因子2B （eIF2B）是真核生物起始因子2 （eIF2）的鸟嘌呤核苷酸交换因子。eIF2B是由α -epsilon亚基组成的异五聚体蛋白。α、β和δ亚基形成调控亚复合物，而γ和ε形成催化亚复合物。古细菌具有eIF2B的α、β和δ亚基的同源物。在这里，我们报告了一个古细菌调节亚基（aIF2Balpha）的三维结构，来自超嗜热古细菌焦球菌（Pyrococcus horikoshii OT3），用x射线晶体学在2.2埃分辨率下测定。aIF2Balpha由两个子结构域组成，一个n结构域（残基1-95）和一个c结构域（残基96-276），由一个长α -螺旋连接（α 5: 78-106）。n结构域包含五螺旋束结构，而c结构域折叠成α / β结构，因此与d -核糖-5-磷酸异构酶结构相似。晶体不对称单元中存在两个分子，凝胶过滤分析表明溶液中的aIF2Balpha为二聚体结构，通过c结构域相互作用。此外，晶体学上的三重对称产生了aIF2Balpha的同六聚体结构，其相互作用主要由n域的长α -螺旋介导。该结构提示了eIF2B调控亚复合物中三个亚基的结构，α， β和δ。(C) 2004爱思唯尔公司版权所有。
Eukaryotic translation initiation factor 2B (eIF2B) is the guanine-nucleotide exchange factor for eukaryotic initiation factor 2 (eIF2). eIF2B is a heteropentameric protein composed of alpha-epsilon subunits. The alpha, beta, and delta subunits form a regulatory subcomplex, while the gamma and epsilon form a catalytic subcomplex. Archaea possess homologues of alpha, beta, and delta subunits of eIF2B. Here, we report the three-dimensional structure of an archaeal regulatory subunit (aIF2Balpha) from the hyperthermophilic archaeon Pyrococcus horikoshii OT3 determined by X-ray crystallography at 2.2 Angstrom resolution. aIF2Balpha consists of two subdomains, an N-domain (residues 1-95) and a C-domain (residues 96-276), connected by a long alpha-helix (alpha5: 78-106). The N-domain contains a five helix bundle structure, while the C-domain folds into the alpha/beta structure, thus showing similarity to D-ribose-5-phosphate isomerase structure. The presence of two molecules in the crystallographic asymmetric unit and the gel filtration analysis suggest a dimeric structure of aIF2Balpha in solution, interacting with each other by C-domains. Furthermore, the crystallographic 3-fold symmetry generates a homohexameric structure of aIF2Balpha the interaction is primarily mediated by the long alpha-helix at the N-domains. This structure suggests an architecture of the three subunits, alpha, beta, and delta, in the regulatory subcomplex within eIF2B. (C) 2004 Elsevier Inc. All rights reserved.