1b8a
From Proteopedia
(New page: 200px<br /><applet load="1b8a" size="450" color="white" frame="true" align="right" spinBox="true" caption="1b8a, resolution 1.90Å" /> '''ASPARTYL-TRNA SYNTHE...) |
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| - | [[Image:1b8a.gif|left|200px]]<br /><applet load="1b8a" size=" | + | [[Image:1b8a.gif|left|200px]]<br /><applet load="1b8a" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1b8a, resolution 1.90Å" /> | caption="1b8a, resolution 1.90Å" /> | ||
'''ASPARTYL-TRNA SYNTHETASE'''<br /> | '''ASPARTYL-TRNA SYNTHETASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystal structure of aspartyl-tRNA synthetase (AspRS) from Pyrococcus | + | The crystal structure of aspartyl-tRNA synthetase (AspRS) from Pyrococcus kodakaraensis was solved at 1.9 A resolution. The sequence and three-dimensional structure of the catalytic domain are highly homologous to those of eukaryotic AspRSs. In contrast, the N-terminal domain, whose function is to bind the tRNA anticodon, is more similar to that of eubacterial enzymes. Its structure explains the unique property of archaeal AspRSs of accommodating both tRNAAsp and tRNAAsn. Soaking the apo-enzyme crystals with ATP and aspartic acid both separately and together allows the adenylate formation to be followed. Due to the asymmetry of the dimeric enzyme in the crystalline state, different steps of the reaction could be visualized within the same crystal. Four different states of the aspartic acid activation reaction could thus be characterized, revealing the functional correlation of the observed conformational changes. The binding of the amino acid substrate induces movement of two invariant loops which secure the position of the peptidyl moiety for adenylate formation. An unambiguous spatial and functional assignment of three magnesium ion cofactors can be made. This study shows the important role of residues present in both archaeal and eukaryotic AspRSs, but absent from the eubacterial enzymes. |
==About this Structure== | ==About this Structure== | ||
| - | 1B8A is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermococcus_kodakarensis Thermococcus kodakarensis] with MN and ATP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Aspartate--tRNA_ligase Aspartate--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.12 6.1.1.12] Full crystallographic information is available from [http:// | + | 1B8A is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermococcus_kodakarensis Thermococcus kodakarensis] with <scene name='pdbligand=MN:'>MN</scene> and <scene name='pdbligand=ATP:'>ATP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Aspartate--tRNA_ligase Aspartate--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.12 6.1.1.12] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1B8A OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Moulinier, L.]] | [[Category: Moulinier, L.]] | ||
[[Category: Schmitt, E.]] | [[Category: Schmitt, E.]] | ||
| - | [[Category: Thierry, J | + | [[Category: Thierry, J C.]] |
[[Category: ATP]] | [[Category: ATP]] | ||
[[Category: MN]] | [[Category: MN]] | ||
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[[Category: trna ligase]] | [[Category: trna ligase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:52:33 2008'' |
Revision as of 09:52, 21 February 2008
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ASPARTYL-TRNA SYNTHETASE
Overview
The crystal structure of aspartyl-tRNA synthetase (AspRS) from Pyrococcus kodakaraensis was solved at 1.9 A resolution. The sequence and three-dimensional structure of the catalytic domain are highly homologous to those of eukaryotic AspRSs. In contrast, the N-terminal domain, whose function is to bind the tRNA anticodon, is more similar to that of eubacterial enzymes. Its structure explains the unique property of archaeal AspRSs of accommodating both tRNAAsp and tRNAAsn. Soaking the apo-enzyme crystals with ATP and aspartic acid both separately and together allows the adenylate formation to be followed. Due to the asymmetry of the dimeric enzyme in the crystalline state, different steps of the reaction could be visualized within the same crystal. Four different states of the aspartic acid activation reaction could thus be characterized, revealing the functional correlation of the observed conformational changes. The binding of the amino acid substrate induces movement of two invariant loops which secure the position of the peptidyl moiety for adenylate formation. An unambiguous spatial and functional assignment of three magnesium ion cofactors can be made. This study shows the important role of residues present in both archaeal and eukaryotic AspRSs, but absent from the eubacterial enzymes.
About this Structure
1B8A is a Single protein structure of sequence from Thermococcus kodakarensis with and as ligands. Active as Aspartate--tRNA ligase, with EC number 6.1.1.12 Full crystallographic information is available from OCA.
Reference
Crystal structure of aspartyl-tRNA synthetase from Pyrococcus kodakaraensis KOD: archaeon specificity and catalytic mechanism of adenylate formation., Schmitt E, Moulinier L, Fujiwara S, Imanaka T, Thierry JC, Moras D, EMBO J. 1998 Sep 1;17(17):5227-37. PMID:9724658
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