1ady
From Proteopedia
(New page: 200px<br /><applet load="1ady" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ady, resolution 2.8Å" /> '''HISTIDYL-TRNA SYNTHET...) |
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| - | [[Image:1ady.gif|left|200px]]<br /><applet load="1ady" size=" | + | [[Image:1ady.gif|left|200px]]<br /><applet load="1ady" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ady, resolution 2.8Å" /> | caption="1ady, resolution 2.8Å" /> | ||
'''HISTIDYL-TRNA SYNTHETASE IN COMPLEX WITH HISTIDYL-ADENYLATE'''<br /> | '''HISTIDYL-TRNA SYNTHETASE IN COMPLEX WITH HISTIDYL-ADENYLATE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystal structure at 2.7 A resolution of histidyl-tRNA synthetase | + | The crystal structure at 2.7 A resolution of histidyl-tRNA synthetase (HisRS) from Thermus thermophilus in complex with its amino acid substrate histidine has been determined. In the crystal asymmetric unit there are two homodimers, each subunit containing 421 amino acid residues. Each monomer of the enzyme consists of three domains: (1) an N-terminal catalytic domain containing a six-stranded antiparallel beta-sheet and the three motifs common to all class II aminoacyl-tRNA synthetases, (2) a 90-residue C-terminal alpha/beta domain which is common to most class IIa synthetases and is probably involved in recognizing the anticodon stem-loop of tRNA(His), and (3) a HisRS-specific alpha-helical domain inserted into the catalytic domain, between motifs II and III. The position of the insertion domain above the catalytic site suggests that it could clamp onto the acceptor stem of the tRNA during aminoacylation. Two HisRS-specific peptides, 259-RGLDYY and 285-GGRYDG, are intimately involved in forming the binding site for the histidine, a molecule of which is found in the active site of each monomer. The structure of HisRS in complex with histidyl adenylate, produced enzymatically in the crystal, has been determined at 3.2 A resolution. This structure shows that the HisRS-specific Arg-259 interacts directly with the alpha-phosphate of the adenylate on the opposite side to the usual conserved motif 2 arginine. Arg-259 thus substitutes for the divalent cation observed in seryl-tRNA synthetase and plays a crucial catalytic role in the mechanism of histidine activation. |
==About this Structure== | ==About this Structure== | ||
| - | 1ADY is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with SO4 and HAM as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Histidine--tRNA_ligase Histidine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.21 6.1.1.21] Full crystallographic information is available from [http:// | + | 1ADY is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=HAM:'>HAM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Histidine--tRNA_ligase Histidine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.21 6.1.1.21] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ADY OCA]. |
==Reference== | ==Reference== | ||
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[[Category: trna synthetase]] | [[Category: trna synthetase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:43:30 2008'' |
Revision as of 09:43, 21 February 2008
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HISTIDYL-TRNA SYNTHETASE IN COMPLEX WITH HISTIDYL-ADENYLATE
Overview
The crystal structure at 2.7 A resolution of histidyl-tRNA synthetase (HisRS) from Thermus thermophilus in complex with its amino acid substrate histidine has been determined. In the crystal asymmetric unit there are two homodimers, each subunit containing 421 amino acid residues. Each monomer of the enzyme consists of three domains: (1) an N-terminal catalytic domain containing a six-stranded antiparallel beta-sheet and the three motifs common to all class II aminoacyl-tRNA synthetases, (2) a 90-residue C-terminal alpha/beta domain which is common to most class IIa synthetases and is probably involved in recognizing the anticodon stem-loop of tRNA(His), and (3) a HisRS-specific alpha-helical domain inserted into the catalytic domain, between motifs II and III. The position of the insertion domain above the catalytic site suggests that it could clamp onto the acceptor stem of the tRNA during aminoacylation. Two HisRS-specific peptides, 259-RGLDYY and 285-GGRYDG, are intimately involved in forming the binding site for the histidine, a molecule of which is found in the active site of each monomer. The structure of HisRS in complex with histidyl adenylate, produced enzymatically in the crystal, has been determined at 3.2 A resolution. This structure shows that the HisRS-specific Arg-259 interacts directly with the alpha-phosphate of the adenylate on the opposite side to the usual conserved motif 2 arginine. Arg-259 thus substitutes for the divalent cation observed in seryl-tRNA synthetase and plays a crucial catalytic role in the mechanism of histidine activation.
About this Structure
1ADY is a Single protein structure of sequence from Thermus thermophilus with and as ligands. Active as Histidine--tRNA ligase, with EC number 6.1.1.21 Full crystallographic information is available from OCA.
Reference
Crystal structure analysis of the activation of histidine by Thermus thermophilus histidyl-tRNA synthetase., Aberg A, Yaremchuk A, Tukalo M, Rasmussen B, Cusack S, Biochemistry. 1997 Mar 18;36(11):3084-94. PMID:9115984
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