View source for 1x54

[[Image:1x54.gif|left|200px]]<br /><applet load="1x54" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="1x54, resolution 1.45&Aring;" />
'''Crystal structure of asparaginyl-tRNA synthetase from Pyrococcus horikoshii complexed with asparaginyl-adenylate'''<br />

==Overview==
Asparaginyl-tRNA synthetase (AsnRS) is a member of the class-II, aminoacyl-tRNA synthetases, and is responsible for catalyzing the specific, aminoacylation of tRNA(Asn) with asparagine. Here, the crystal structure, of AsnRS from Pyrococcus horikoshii, complexed with asparaginyl-adenylate, (Asn-AMP), was determined at 1.45 A resolution, and those of free AsnRS, and AsnRS complexed with an Asn-AMP analog (Asn-SA) were solved at 1.98, and 1.80 A resolutions, respectively. All of the crystal structures have, many solvent molecules, which form a network of hydrogen-bonding, interactions that surrounds the entire AsnRS molecule. In the, AsnRS/Asn-AMP complex (or the AsnRS/Asn-SA), one side of the bound Asn-AMP, (or Asn-SA) is completely covered by the solvent molecules, which, complement the binding site. In particular, two of these water molecules, were found to interact directly with the asparagine amide and carbonyl, groups, respectively, and to contribute to the formation of a pocket, highly complementary to the asparagine side-chain. Thus, these two water, molecules appear to play a key role in the strict recognition of, asparagine and the discrimination against aspartic acid by the AsnRS. This, water-assisted asparagine recognition by the AsnRS strikingly contrasts, with the fact that the aspartic acid recognition by the closely related, aspartyl-tRNA synthetase is achieved exclusively through extensive, interactions with protein amino acid residues. Furthermore, based on a, docking model of AsnRS and tRNA, a single arginine residue (Arg83) in the, AsnRS was postulated to be involved in the recognition of the third, position of the tRNA(Asn) anticodon (U36). We performed a mutational, analysis of this particular arginine residue, and confirmed its, significance in the tRNA recognition.

==About this Structure==
1X54 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pyrococcus_horikoshii Pyrococcus horikoshii] with MG, 4AD and MPD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Asparagine--tRNA_ligase Asparagine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.22 6.1.1.22] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1X54 OCA]. 

==Reference==
Structural basis of the water-assisted asparagine recognition by asparaginyl-tRNA synthetase., Iwasaki W, Sekine S, Kuroishi C, Kuramitsu S, Shirouzu M, Yokoyama S, J Mol Biol. 2006 Jul 7;360(2):329-42. Epub 2006 May 15. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16753178 16753178]
[[Category: Asparagine--tRNA ligase]]
[[Category: Pyrococcus horikoshii]]
[[Category: Single protein]]
[[Category: Iwasaki, W.]]
[[Category: RSGI, RIKEN.Structural.Genomics/Proteomics.Initiative.]]
[[Category: Sekine, S.]]
[[Category: Yokoyama, S.]]
[[Category: 4AD]]
[[Category: MG]]
[[Category: MPD]]
[[Category: aminoacyl-trna synthetase]]
[[Category: riken structural genomics/proteomics initiative]]
[[Category: rsgi]]
[[Category: structural genomics]]

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