1evk: Difference between revisions

Revision as of 13:32, 21 February 2008

CRYSTAL STRUCTURE OF A TRUNCATED FORM OF THREONYL-TRNA SYNTHETASE WITH THE LIGAND THREONINE

OverviewOverview

Accurate translation of the genetic code depends on the ability of aminoacyl-tRNA synthetases to distinguish between similar amino acids. In order to investigate the basis of amino acid recognition and to understand the role played by the zinc ion present in the active site of threonyl-tRNA synthetase, we have determined the crystal structures of complexes of an active truncated form of the enzyme with a threonyl adenylate analog or threonine. The zinc ion is directly involved in threonine recognition, forming a pentacoordinate intermediate with both the amino group and the side chain hydroxyl. Amino acid activation experiments reveal that the enzyme shows no activation of isosteric valine, and activates serine at a rate 1,000-fold less than that of cognate threonine. This study demonstrates that the zinc ion is neither strictly catalytic nor structural and suggests how the zinc ion ensures that only amino acids that possess a hydroxyl group attached to the beta-position are activated.

About this StructureAbout this Structure

1EVK is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Threonine--tRNA ligase, with EC number 6.1.1.3 Full crystallographic information is available from OCA.

ReferenceReference

Zinc ion mediated amino acid discrimination by threonyl-tRNA synthetase., Sankaranarayanan R, Dock-Bregeon AC, Rees B, Bovee M, Caillet J, Romby P, Francklyn CS, Moras D, Nat Struct Biol. 2000 Jun;7(6):461-5. PMID:10881191

Page seeded by OCA on Thu Feb 21 12:31:56 2008

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OCA

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-[[Image:1evk.gif|left|200px]]<br /><applet load="1evk" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1evk.gif|left|200px]]<br /><applet load="1evk" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1evk, resolution 2.00&Aring;" />
 '''CRYSTAL STRUCTURE OF A TRUNCATED FORM OF THREONYL-TRNA SYNTHETASE WITH THE LIGAND THREONINE'''<br />
 ==Overview==
-Accurate translation of the genetic code depends on the ability of, aminoacyl-tRNA synthetases to distinguish between similar amino acids. In, order to investigate the basis of amino acid recognition and to understand, the role played by the zinc ion present in the active site of, threonyl-tRNA synthetase, we have determined the crystal structures of, complexes of an active truncated form of the enzyme with a threonyl, adenylate analog or threonine. The zinc ion is directly involved in, threonine recognition, forming a pentacoordinate intermediate with both, the amino group and the side chain hydroxyl. Amino acid activation, experiments reveal that the enzyme shows no activation of isosteric, valine, and activates serine at a rate 1,000-fold less than that of, cognate threonine. This study demonstrates that the zinc ion is neither, strictly catalytic nor structural and suggests how the zinc ion ensures, that only amino acids that possess a hydroxyl group attached to the, beta-position are activated.
+Accurate translation of the genetic code depends on the ability of aminoacyl-tRNA synthetases to distinguish between similar amino acids. In order to investigate the basis of amino acid recognition and to understand the role played by the zinc ion present in the active site of threonyl-tRNA synthetase, we have determined the crystal structures of complexes of an active truncated form of the enzyme with a threonyl adenylate analog or threonine. The zinc ion is directly involved in threonine recognition, forming a pentacoordinate intermediate with both the amino group and the side chain hydroxyl. Amino acid activation experiments reveal that the enzyme shows no activation of isosteric valine, and activates serine at a rate 1,000-fold less than that of cognate threonine. This study demonstrates that the zinc ion is neither strictly catalytic nor structural and suggests how the zinc ion ensures that only amino acids that possess a hydroxyl group attached to the beta-position are activated.
 ==About this Structure==
-EVK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with ZN and THR as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Threonine--tRNA_ligase Threonine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.3 6.1.1.3] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1EVK OCA].
+EVK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=THR:'>THR</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Threonine--tRNA_ligase Threonine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.3 6.1.1.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EVK OCA].
 ==Reference==
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 [[Category: Single protein]]
 [[Category: Threonine--tRNA ligase]]
-[[Category: Dock-Bregeon, A.C.]]
+[[Category: Dock-Bregeon, A C.]]
 [[Category: Moras, D.]]
 [[Category: Rees, B.]]
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 [[Category: zinc ion]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 14:21:25 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:31:56 2008''