Cahuzac B, Berthonneau E, Birlirakis N, Guittet E, Mirande M
Laboratoire de RMN, ICSN-CNRS, Gif-sur-Yvette, France.
EMBO J. 2000 Feb 1;19(3):445-52. doi: 10.1093/emboj/19.3.445.
Aminoacyl-tRNA synthetases of higher eukaryotes possess polypeptide extensions in contrast to their prokaryotic counterparts. These extra domains of poorly understood function are believed to be involved in protein-protein or protein-RNA interactions. Here we showed by gel retardation and filter binding experiments that the repeated units that build the linker region of the bifunctional glutamyl-prolyl-tRNA synthetase had a general RNA-binding capacity. The solution structure of one of these repeated motifs was also solved by NMR spectroscopy. One repeat is built around an antiparallel coiled-coil. Strikingly, the conserved lysine and arginine residues form a basic patch on one side of the structure, presenting a suitable docking surface for nucleic acids. Therefore, this repeated motif may represent a novel type of general RNA-binding domain appended to eukaryotic aminoacyl-tRNA synthetases to serve as a cis-acting tRNA-binding cofactor.
与原核生物的氨酰-tRNA合成酶相比，高等真核生物的氨酰-tRNA合成酶具有多肽延伸部分。这些功能尚不清楚的额外结构域被认为参与蛋白质-蛋白质或蛋白质-RNA相互作用。在这里，我们通过凝胶阻滞和滤膜结合实验表明，构成双功能谷氨酰胺-脯氨酰-tRNA合成酶连接区的重复单元具有一般的RNA结合能力。其中一个重复基序的溶液结构也通过核磁共振光谱法解析出来。一个重复单元围绕着一个反平行卷曲螺旋构建而成。引人注目的是，保守的赖氨酸和精氨酸残基在结构的一侧形成一个碱性区域，为核酸提供了一个合适的对接表面。因此，这个重复基序可能代表了一种新型的一般RNA结合结构域，附加到真核生物氨酰-tRNA合成酶上，作为一种顺式作用的tRNA结合辅助因子。
