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PDBsum entry 1a8h
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Aminoacyl-tRNA synthetase
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PDB id
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1a8h
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References listed in PDB file
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Key reference
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Title
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The 2.0 a crystal structure of thermus thermophilus methionyl-Trna synthetase reveals two rna-Binding modules.
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Authors
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I.Sugiura,
O.Nureki,
Y.Ugaji-Yoshikawa,
S.Kuwabara,
A.Shimada,
M.Tateno,
B.Lorber,
R.Giegé,
D.Moras,
S.Yokoyama,
M.Konno.
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Ref.
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Structure, 2000,
8,
197-208.
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PubMed id
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Abstract
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BACKGROUND: The 20 aminoacyl-tRNA synthetases are divided into two classes, I
and II. The 10 class I synthetases are considered to have in common the
catalytic domain structure based on the Rossmann fold, which is totally
different from the class II catalytic domain structure. The class I synthetases
are further divided into three subclasses, a, b and c, according to sequence
homology. No conserved structural features for tRNA recognition by class I
synthetases have been established. RESULTS: We determined the crystal structure
of the class Ia methionyl-tRNA synthetase (MetRS) at 2.0 A resolution, using
MetRS from an extreme thermophile, Thermus thermophilus HB8. The T. thermophilus
MetRS structure is in full agreement with the biochemical and genetic data from
Escherichia coli MetRS. The conserved 'anticodon-binding' residues are spatially
clustered on an alpha-helix-bundle domain. The Rossmann-fold and
anticodon-binding domains are connected by a beta-alpha-alpha-beta-alpha
topology ('SC fold') domain that contains the class I specific KMSKS motif.
CONCLUSIONS: The alpha-helix-bundle domain identified in the MetRS structure is
the signature of the class Ia enzymes, as it was also identified in the class Ia
structures of the isoleucyl- and arginyl-tRNA synthetases. The
beta-alpha-alpha-beta-alpha topology domain, which can now be identified in all
known structures of the class Ia and Ib synthetases, is likely to dock with the
inner side of the L-shaped tRNA, thereby positioning the anticodon stem.
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