1gts
From Proteopedia
(New page: 200px<br /><applet load="1gts" size="450" color="white" frame="true" align="right" spinBox="true" caption="1gts, resolution 2.800Å" /> '''STRUCTURAL BASIS FO...) |
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| - | [[Image:1gts.jpg|left|200px]]<br /><applet load="1gts" size=" | + | [[Image:1gts.jpg|left|200px]]<br /><applet load="1gts" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1gts, resolution 2.800Å" /> | caption="1gts, resolution 2.800Å" /> | ||
'''STRUCTURAL BASIS FOR TRANSFER RNA AMINOACEYLATION BY ESCHERICHIA COLI GLUTAMINYL-TRNA SYNTHETASE'''<br /> | '''STRUCTURAL BASIS FOR TRANSFER RNA AMINOACEYLATION BY ESCHERICHIA COLI GLUTAMINYL-TRNA SYNTHETASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The structure of Escherichia coli glutaminyl-tRNA synthetase complexed | + | The structure of Escherichia coli glutaminyl-tRNA synthetase complexed with tRNA2Gln and ATP refined at 2.5-A resolution reveals structural details of the catalytic center and allows description of the specific roles of individual amino acid residues in substrate binding and catalysis. The reactive moieties of the ATP and tRNA substrates are positioned within hydrogen-bonding distance of each other. Model-building has been used to position the glutamine substrate in an adjacent cavity with its reactive carboxylate adjacent to the alpha-phosphate of ATP; the interactions of the carboxyamide side chain suggest a structural rationale for the way in which the enzyme discriminates against glutamate. The binding site for a manganese ion has also been identified bridging the beta- and gamma-phosphates of the ATP. The well-known HIGH and KMSKS sequence motifs interact directly with each other as well as with the ATP, providing a structural rationale for their simultaneous conservation in all class I synthetases. The KMSKS loop adopts a well-ordered and catalytically productive conformation as a consequence of interactions made with the proximal beta-barrel domain. While there are no protein side chains near the reaction site that might function in acid-base catalysis, the side chains of two residues, His43 and Lys270, are positioned to assist in stabilizing the expected pentacovalent intermediate at the alpha-phosphate. Transfer of glutamine to the 3'-terminal tRNA ribose may well proceed by intramolecular catalysis involving proton abstraction by a phosphate oxygen atom of glutaminyl adenylate. Catalytic competence of the crystalline enzyme is directly shown by its ability to hydrolyze ATP and release pyrophosphate when crystals of the ternary complex are soaked in mother liquor containing glutamine. |
==About this Structure== | ==About this Structure== | ||
| - | 1GTS 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 AMP as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1GTS 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=AMP:'>AMP</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GTS OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Perona, T | + | [[Category: Perona, T A.Steitz J J.]] |
| - | [[Category: Rould, M | + | [[Category: Rould, M A.]] |
[[Category: AMP]] | [[Category: AMP]] | ||
[[Category: protein-rna complex]] | [[Category: protein-rna complex]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:53:55 2008'' |
Revision as of 10:53, 21 February 2008
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STRUCTURAL BASIS FOR TRANSFER RNA AMINOACEYLATION BY ESCHERICHIA COLI GLUTAMINYL-TRNA SYNTHETASE
Overview
The structure of Escherichia coli glutaminyl-tRNA synthetase complexed with tRNA2Gln and ATP refined at 2.5-A resolution reveals structural details of the catalytic center and allows description of the specific roles of individual amino acid residues in substrate binding and catalysis. The reactive moieties of the ATP and tRNA substrates are positioned within hydrogen-bonding distance of each other. Model-building has been used to position the glutamine substrate in an adjacent cavity with its reactive carboxylate adjacent to the alpha-phosphate of ATP; the interactions of the carboxyamide side chain suggest a structural rationale for the way in which the enzyme discriminates against glutamate. The binding site for a manganese ion has also been identified bridging the beta- and gamma-phosphates of the ATP. The well-known HIGH and KMSKS sequence motifs interact directly with each other as well as with the ATP, providing a structural rationale for their simultaneous conservation in all class I synthetases. The KMSKS loop adopts a well-ordered and catalytically productive conformation as a consequence of interactions made with the proximal beta-barrel domain. While there are no protein side chains near the reaction site that might function in acid-base catalysis, the side chains of two residues, His43 and Lys270, are positioned to assist in stabilizing the expected pentacovalent intermediate at the alpha-phosphate. Transfer of glutamine to the 3'-terminal tRNA ribose may well proceed by intramolecular catalysis involving proton abstraction by a phosphate oxygen atom of glutaminyl adenylate. Catalytic competence of the crystalline enzyme is directly shown by its ability to hydrolyze ATP and release pyrophosphate when crystals of the ternary complex are soaked in mother liquor containing glutamine.
About this Structure
1GTS is a Single protein structure of sequence from Escherichia coli with as ligand. Full crystallographic information is available from OCA.
Reference
Structural basis for transfer RNA aminoacylation by Escherichia coli glutaminyl-tRNA synthetase., Perona JJ, Rould MA, Steitz TA, Biochemistry. 1993 Aug 31;32(34):8758-71. PMID:8364025
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