1o0c
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1o0c" size="450" color="white" frame="true" align="right" spinBox="true" caption="1o0c, resolution 2.70Å" /> '''CRYSTAL STRUCTURE OF...)
Next diff →
Revision as of 20:35, 20 November 2007
|
CRYSTAL STRUCTURE OF L-GLUTAMATE AND AMPCPP BOUND TO GLUTAMINE AMINOACYL TRNA SYNTHETASE
Overview
The 2.5 A crystal structure of Escherichia coli glutaminyl-tRNA synthetase, in a quaternary complex with tRNA(Gln), an ATP analog and glutamate, reveals that the non-cognate amino acid adopts a distinct binding mode, within the active site cleft. In contrast to the binding of cognate, glutamine, one oxygen of the charged glutamate carboxylate group makes a, direct ion-pair interaction with the strictly conserved Arg30 residue, located in the first half of the dinucleotide fold domain. The, nucleophilic alpha-carboxylate moiety of glutamate is mispositioned with, respect to both the ATP alpha-phosphate and terminal tRNA ribose groups, suggesting that a component of amino acid discrimination resides at the, catalytic step of the reaction. Further, the other side-chain carboxylate, oxygen of glutamate is found in a position identical to that previously, proposed to be occupied by the NH(2) group of the cognate glutamine, substrate. At this position, the glutamate oxygen accepts hydrogen bonds, from the hydroxyl moiety of Tyr211 and a water molecule. These findings, demonstrate that amino acid specificity by GlnRS cannot arise from, hydrogen bonds donated by the cognate glutamine amide to these same, moieties, as previously suggested. Instead, Arg30 functions as a negative, determinant to drive binding of non-cognate glutamate into a, non-productive orientation. The poorly differentiated cognate amino, acid-binding site in GlnRS may be a consequence of the late emergence of, this enzyme from the eukaryotic lineage of glutamyl-tRNA synthetases.
About this Structure
1O0C is a Protein complex structure of sequences from Escherichia coli with SO4, GLU and AMP as ligands. Active as Glutamine--tRNA ligase, with EC number 6.1.1.18 Full crystallographic information is available from OCA.
Reference
Amino acid discrimination by a class I aminoacyl-tRNA synthetase specified by negative determinants., Bullock TL, Uter N, Nissan TA, Perona JJ, J Mol Biol. 2003 Apr 25;328(2):395-408. PMID:12691748
Page seeded by OCA on Tue Nov 20 22:42:15 2007
