Structure and dynamics of translation initiation factor aIF-1A from the archaeon Methanococcus jannaschii determined by NMR spectroscopy
Structure and dynamics of translation initiation factor aIF-1A from the archaeon Methanococcus jannaschii determined by NMR spectroscopy
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DOI：
10.1110/ps.ps.18201
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发表时间：
2001-12-01
期刊：
影响因子：
8
通讯作者：
Hoffman, DW
中科院分区：
文献类型：
--
作者：
Li, W;Hoffman, DW
来自jannaschii的甲虫球菌的翻译起始因子1a（AIF-1A）在大肠杆菌中表达，使用多维NMR方法以其结构和动力学来纯化和表征。发现该蛋白是与RNA相关蛋白的OB折成家的成员，其中包含五个桶式链链的桶，该特征与同源真核翻译起始因子1A（EIF-1A）共享。作为核翻译起始因子IF1。 AIF-1A在β枪管外部包含其C末端的Alpha-helix，并且在其N末端包含一个柔性环，其特征在质量上与EIF-1A中发现的特征相似，但在原核生物IF1中不存在。 AIF-1A的结构模型与不同物种中AIF-1A的主要序列信息结合使用时，允许鉴定蛋白质表面上最保存的残基，包括与16S核糖体直接相互作用的最有可能的候选者RNA和翻译设备的其他组件。几个保守的表面残基似乎是古细菌所独有的。氮-15松弛和酰胺汇率数据用于表征AIF-1A内的内部运动，提供证据表明最有可能参与分子间相互作用的蛋白质表面相对灵活。提出了一个模型，表明AIF-1A与古细菌核糖体的小亚基之间可能发生一些特定的相互作用。
Translation initiation factor 1A (aIF-1A) from the archaeon Methanococcus jannaschii was expressed in Escherichia coli, purified, and characterized in terms of its structure and dynamics using multidimensional NMR methods. The protein was found to be a member of the OB-fold family of RNA-associated proteins, containing a barrel of five beta-strands, a feature that is shared with the homologous eukaryotic translation initiation factor 1A (eIF-1A), as well as the prokaryotic translation initiation factor IF1. External to the beta barrel, aIF-1A contains an alpha -helix at its C-terminal and a flexible loop at its N-terminal, features that are qualitatively similar to those found in eIF-1A, but not present in prokaryotic IF1. The structural model of aIF-1A, when used in combination with primary sequence information for aIF-1A in divergent species, permitted the most-conserved residues on the protein surface to be identified, including the most likely candidates for direct interaction with the 16S ribosomal RNA and other components of the translational apparatus. Several of the conserved surface residues appear to be unique to the archaea. Nitrogen-15 relaxation and amide exchange rate data were used to characterize the internal motions within aIF-1A, providing evidence that the protein surfaces that are most likely to participate in intermolecular interactions are relatively flexible. A model is proposed, suggesting some specific interactions that may occur between aIF-1A and the small subunit of the archaeal ribosome.