Breton R, Watson D, Yaguchi M, Lapointe J
Département de Biochimie, Faculté des Sciences et de Génie, Université Laval, Québec, Canada.
J Biol Chem. 1990 Oct 25;265(30):18248-55.
The glutamyl-tRNA synthetase (GluRS) of Bacillus subtilis 168T aminoacylates with glutamate its homologous tRNA(Glu) and tRNA(Gln) in vivo and Escherichia coli tRNA(1Gln) in vitro (Lapointe, J., Duplain, L., and Proulx, M. (1986) J. Bacteriol. 165, 88-93). The gltX gene encoding this enzyme was cloned and sequenced. It encodes a protein of 483 amino acids with a Mr of 55,671. Alignment of the amino acid sequences of four bacterial GluRSs (from B. subtilis, Bacillus stearothermophilus, E. coli, and Rhizobium meliloti) gives 20% identity and reveals the presence of several short highly conserved motifs in the first two thirds of these proteins. Conserved motifs are found at corresponding positions in several other aminoacyl-tRNA synthetases. The only sequence similarity between the GluRSs of these Bacillus species and the E. coli glutaminyl-tRNA synthetase (GlnRS), which has no counterpart in the E. coli GluRS, is in a segment of 30 amino acids in the last third of these synthetases. In the three-dimensional structure of the E. coli tRNA(Gln).GlnRS.ATP complex, this conserved peptide is near the anticodon of tRNA(Gln) (Rould, M. A., Perona, J. J., Söll, D., and Steitz, T. A. (1989) Science 246, 1135-1142), suggesting that this region is involved in the specific interactions between these enzymes and the anticodon regions of their tRNA substrates.
枯草芽孢杆菌168T的谷氨酰胺-tRNA合成酶（GluRS）在体内能将谷氨酸与同源的tRNA（Glu）和tRNA（Gln）进行氨酰化反应，在体外能将谷氨酸与大肠杆菌的tRNA（1Gln）进行氨酰化反应（拉波因特，J.，迪普兰，L.，和普鲁克斯，M.（1986年）《细菌学杂志》165，88 - 93）。编码该酶的gltX基因被克隆并测序。它编码一个由483个氨基酸组成的蛋白质，分子量为55,671。对四种细菌GluRS（来自枯草芽孢杆菌、嗜热脂肪芽孢杆菌、大肠杆菌和苜蓿根瘤菌）的氨基酸序列进行比对，发现它们有20%的同源性，并揭示在这些蛋白质的前三分之二区域存在几个短的高度保守基序。在其他几种氨酰-tRNA合成酶的相应位置也发现了保守基序。这些芽孢杆菌属物种的GluRS与大肠杆菌谷氨酰胺-tRNA合成酶（GlnRS）之间唯一的序列相似性（大肠杆菌GluRS中没有对应序列），存在于这些合成酶后三分之一区域的一段30个氨基酸的片段中。在大肠杆菌tRNA（Gln）.GlnRS.ATP复合物的三维结构中，这个保守肽靠近tRNA（Gln）的反密码子（鲁尔德，M. A.，佩罗纳，J. J.，索尔，D.，和施泰茨，T. A.（1989年）《科学》246，1135 - 1142），这表明该区域参与了这些酶与其tRNA底物反密码子区域之间的特异性相互作用。
