1zjw
From Proteopedia
| Line 1: | Line 1: | ||
[[Image:1zjw.gif|left|200px]] | [[Image:1zjw.gif|left|200px]] | ||
| - | + | <!-- | |
| - | + | The line below this paragraph, containing "STRUCTURE_1zjw", creates the "Structure Box" on the page. | |
| - | + | You may change the PDB parameter (which sets the PDB file loaded into the applet) | |
| - | + | or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |
| - | + | or leave the SCENE parameter empty for the default display. | |
| - | | | + | --> |
| - | | | + | {{STRUCTURE_1zjw| PDB=1zjw | SCENE= }} |
| - | + | ||
| - | + | ||
| - | }} | + | |
'''Glutaminyl-tRNA synthetase complexed to glutamine and 2'deoxy A76 glutamine tRNA''' | '''Glutaminyl-tRNA synthetase complexed to glutamine and 2'deoxy A76 glutamine tRNA''' | ||
| Line 30: | Line 27: | ||
[[Category: Perona, J J.]] | [[Category: Perona, J J.]] | ||
[[Category: Uter, N.]] | [[Category: Uter, N.]] | ||
| - | [[Category: | + | [[Category: Protein-rna complex]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:42:51 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 14:42, 3 May 2008
Glutaminyl-tRNA synthetase complexed to glutamine and 2'deoxy A76 glutamine tRNA
Overview
Glutaminyl-tRNA synthetase generates Gln-tRNA(Gln) 10(7)-fold more efficiently than Glu-tRNA(Gln) and requires tRNA to synthesize the activated aminoacyl adenylate in the first step of the reaction. To examine the role of tRNA in amino acid activation more closely, several assays employing a tRNA analog in which the 2'-OH group at the 3'-terminal A76 nucleotide is replaced with hydrogen (tRNA(2'HGln)) were developed. These experiments revealed a 10(4)-fold reduction in kcat/Km in the presence of the analog, suggesting a direct catalytic role for tRNA in the activation reaction. The catalytic importance of the A76 2'-OH group in aminoacylation mirrors a similar role for this moiety that has recently been demonstrated during peptidyl transfer on the ribosome. Unexpectedly, tracking of Gln-AMP formation utilizing an alpha-32P-labeled ATP substrate in the presence of tRNA(2'HGln) showed that AMP accumulates 5-fold more rapidly than Gln-AMP. A cold-trapping experiment revealed that the nonenzymatic rate of Gln-AMP hydrolysis is too slow to account for the rapid AMP formation; hence, the hydrolysis of Gln-AMP to form glutamine and AMP must be directly catalyzed by the GlnRS x tRNA(2'HGln) complex. This hydrolysis of glutaminyl adenylate represents a novel reaction that is directly analogous to the pre-transfer editing hydrolysis of noncognate aminoacyl adenylates by editing synthetases such as isoleucyl-tRNA synthetase. Because glutaminyl-tRNA synthetase does not possess a spatially separate editing domain, these data demonstrate that a pre-transfer editing-like reaction can occur within the synthetic site of a class I tRNA synthetase.
About this Structure
1ZJW is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
tRNA-dependent aminoacyl-adenylate hydrolysis by a nonediting class I aminoacyl-tRNA synthetase., Gruic-Sovulj I, Uter N, Bullock T, Perona JJ, J Biol Chem. 2005 Jun 24;280(25):23978-86. Epub 2005 Apr 20. PMID:15845536 Page seeded by OCA on Sat May 3 17:42:51 2008
