Wu Huiwen, Gong Weibin, Yao Xingzhe, Wang Jinfeng, Perrett Sarah, Feng Yingang
From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, the University of Chinese Academy of Sciences, Beijing 100049, China.
From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101.
J Biol Chem. 2015 Apr 3;290(14):8694-710. doi: 10.1074/jbc.M114.628594. Epub 2015 Jan 29.
Translationally controlled tumor protein (TCTP) is an abundant protein that is highly conserved in eukaryotes. However, its primary function is still not clear. Human TCTP interacts with the metazoan-specific eukaryotic elongation factor 1Bδ (eEF1Bδ) and inhibits its guanine nucleotide exchange factor (GEF) activity, but the structural mechanism remains unknown. The interaction between TCTP and eEF1Bδ was investigated by NMR titration, structure determination, paramagnetic relaxation enhancement, site-directed mutagenesis, isothermal titration calorimetry, and HADDOCK docking. We first demonstrated that the catalytic GEF domain of eEF1Bδ is not responsible for binding to TCTP but rather a previously unnoticed central acidic region (CAR) domain in eEF1Bδ. The mutagenesis data and the structural model of the TCTP-eEF1Bδ CAR domain complex revealed the key binding residues. These residues are highly conserved in eukaryotic TCTPs and in eEF1B GEFs, including the eukaryotically conserved eEF1Bα, implying the interaction may be conserved in all eukaryotes. Interactions were confirmed between TCTP and the eEF1Bα CAR domain for human, fission yeast, and unicellular photosynthetic microalgal proteins, suggesting that involvement in protein translation through the conserved interaction with eEF1B represents a primary function of TCTP.
翻译调控肿瘤蛋白（TCTP）是一种在真核生物中高度保守的丰富蛋白质。然而，其主要功能仍不清楚。人类TCTP与后生动物特有的真核延伸因子1Bδ（eEF1Bδ）相互作用，并抑制其鸟嘌呤核苷酸交换因子（GEF）活性，但其结构机制仍然未知。通过核磁共振滴定、结构测定、顺磁弛豫增强、定点诱变、等温滴定量热法和HADDOCK对接研究了TCTP与eEF1Bδ之间的相互作用。我们首先证明，eEF1Bδ的催化GEF结构域并非负责与TCTP结合，而是eEF1Bδ中一个先前未被注意到的中央酸性区域（CAR）结构域。TCTP-eEF1Bδ CAR结构域复合物的诱变数据和结构模型揭示了关键的结合残基。这些残基在真核TCTP和eEF1B GEF中高度保守，包括真核保守的eEF1Bα，这意味着这种相互作用可能在所有真核生物中都是保守的。已证实人类、裂殖酵母和单细胞光合微藻蛋白的TCTP与eEF1Bα CAR结构域之间存在相互作用，这表明通过与eEF1B的保守相互作用参与蛋白质翻译是TCTP的主要功能。
