2cfo

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Image:2cfo.gif

2cfo, resolution 2.45Å

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NON-DISCRIMINATING GLUTAMYL-TRNA SYNTHETASE FROM THERMOSYNECHOCOCCUS ELONGATUS IN COMPLEX WITH GLU

Overview

Error-free protein biosynthesis is dependent on the reliable charging of, each tRNA with its cognate amino acid. Many bacteria, however, lack a, glutaminyl-tRNA synthetase. In these organisms, tRNA(Gln) is initially, mischarged with glutamate by a non-discriminating glutamyl-tRNA synthetase, (ND-GluRS). This enzyme thus charges both tRNA(Glu) and tRNA(Gln) with, glutamate. Discriminating GluRS (D-GluRS), found in some bacteria and all, eukaryotes, exclusively generates Glu-tRNA(Glu). Here we present the first, crystal structure of a non-discriminating GluRS from Thermosynechococcus, elongatus (ND-GluRS(Tel)) in complex with glutamate at a resolution of, 2.45 A. Structurally, the enzyme shares the overall architecture of the, discriminating GluRS from Thermus thermophilus (D-GluRS(Tth)). We confirm, experimentally that GluRS(Tel) is non-discriminating and present kinetic, parameters for synthesis of Glu-tRNA(Glu) and of Glu-tRNA(Gln). Anticodons, of tRNA(Glu) (34C/UUC36) and tRNA(Gln) (34C/UUG36) differ only in base 36., The pyrimidine base of C36 is specifically recognized in D-GluRS(Tth) by, the residue Arg358. In ND-GluRS(Tel) this arginine residue is replaced by, glycine (Gly366) presumably allowing both cytosine and the bulkier purine, base G36 of tRNA(Gln) to be tolerated. Most other ND-GluRS share this, structural feature, leading to relaxed substrate specificity.

About this Structure

2CFO is a Single protein structure of sequence from Synechococcus elongatus with as ligand. Active as Glutamate--tRNA ligase, with EC number 6.1.1.17 Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Crystal structure of a non-discriminating glutamyl-tRNA synthetase., Schulze JO, Masoumi A, Nickel D, Jahn M, Jahn D, Schubert WD, Heinz DW, J Mol Biol. 2006 Sep 1;361(5):888-97. Epub 2006 Jul 5. PMID:16876193

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