Dominguez D, Altmann M, Benz J, Baumann U, Trachsel H
Institute for Biochemistry and Molecular Biology, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.
J Biol Chem. 1999 Sep 17;274(38):26720-6. doi: 10.1074/jbc.274.38.26720.
Eukaryotic initiation factor (eIF) 4A is an essential protein that, in conjunction with eIF4B, catalyzes the ATP-dependent melting of RNA secondary structure in the 5'-untranslated region of mRNA during translation initiation. In higher eukaryotes, eIF4A is assumed to be recruited to the mRNA through its interaction with eIF4G. However, the failure to detect this interaction in yeast brought into question the generality of this model. The work presented here demonstrates that yeast eIF4G interacts with eIF4A both in vivo and in vitro. The eIF4A-binding site was mapped to amino acids 542-883 of yeast eIF4G1. Expression in yeast cells of the eIF4G1 domain that binds eIF4A results in cell growth inhibition, and addition of this domain to an eIF4A-dependent in vitro system inhibits translation in a dose-dependent manner. Both in vitro translation and cell growth can be specifically restored by increasing the eIF4A concentration. These data demonstrate that yeast eIF4A and eIF4G interact and suggest that this interaction is required for translation and cell growth.
真核生物起始因子（eIF）4A是一种必需蛋白，在翻译起始过程中，它与eIF4B协同作用，催化mRNA 5'非翻译区RNA二级结构的ATP依赖性解链。在高等真核生物中，eIF4A被认为是通过与eIF4G相互作用而被招募到mRNA上的。然而，在酵母中未能检测到这种相互作用，这使得该模型的普遍性受到质疑。本文所展示的工作表明，酵母eIF4G在体内和体外均与eIF4A相互作用。eIF4A结合位点被定位到酵母eIF4G1的542 - 883位氨基酸。在酵母细胞中表达与eIF4A结合的eIF4G1结构域会导致细胞生长受到抑制，并且将该结构域添加到依赖eIF4A的体外系统中会以剂量依赖的方式抑制翻译。通过增加eIF4A浓度可以特异性地恢复体外翻译和细胞生长。这些数据表明酵母eIF4A和eIF4G相互作用，并表明这种相互作用是翻译和细胞生长所必需的。
