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PDBsum entry 1gts
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Structural basis for transfer RNA aminoacylation by escherichia coli glutaminyl-Trna synthetase.
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Authors
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J.J.Perona,
M.A.Rould,
T.A.Steitz.
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Ref.
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Biochemistry, 1993,
32,
8758-8771.
[DOI no: ]
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PubMed id
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Abstract
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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.
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Secondary reference #1
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Title
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Structural basis of anticodon loop recognition by glutaminyl-Trna synthetase.
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Authors
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M.A.Rould,
J.J.Perona,
T.A.Steitz.
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Ref.
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Nature, 1991,
352,
213-218.
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PubMed id
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