1qtq

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spinqualitylabelsall models 1qtq, resolution 2.250Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

GLUTAMINYL-TRNA SYNTHETASE COMPLEXED WITH TRNA AND AN AMINO ACID ANALOG

Overview

BACKGROUND: Aminoacyl-tRNA synthetases covalently link a specific amino, acid to the correct tRNA. The fidelity of this reaction is essential for, accurate protein synthesis. Each synthetase has a specific molecular, mechanism to distinguish the correct pair of substrates from the pool of, amino acids and isologous tRNA molecules. In the case of glutaminyl-tRNA, synthetase (GlnRS) the prior binding of tRNA is required for activation of, glutamine by ATP. A complete understanding of amino acid specificity in, GlnRS requires the determination of the structure of the synthetase with, both tRNA and substrates bound. RESULTS: A stable glutaminly-adenylate, analog, which inhibits GlnRS with a Ki of 1.32 microM, was synthesized and, cocrystallized with GlnRS and tRNA2Gln. The crystal structure of this, ternary complex has been refined at 2.4 A resolution and shows the, interactions made between glutamine and its binding site. CONCLUSIONS: To, select against glutamic acid or glutamate, both hydrogen atoms of the, nitrogen of the glutamine sidechain are recognized. The hydroxyl group of, Tyr211 and a water molecule are responsible for this recognition; both are, obligate hydrogen-bond acceptors due to a network of interacting, sidechains and water molecules. The prior binding of tRNAGln that is, required for amino acid activation may result from the terminal, nucleotide, A76, packing against and orienting Tyr211, which forms part of, the amino acid binding site.

About this Structure

1QTQ is a Single protein structure of sequence from Escherichia coli with SO4 and QSI as ligands. Active as Glutamine--tRNA ligase, with EC number 6.1.1.18 Full crystallographic information is available from OCA.

Reference

How glutaminyl-tRNA synthetase selects glutamine., Rath VL, Silvian LF, Beijer B, Sproat BS, Steitz TA, Structure. 1998 Apr 15;6(4):439-49. PMID:9562563

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