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PDBsum entry 3h37
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References listed in PDB file
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Key reference
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Title
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Mechanism for the definition of elongation and termination by the class ii cca-Adding enzyme.
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Authors
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Y.Toh,
D.Takeshita,
T.Numata,
S.Fukai,
O.Nureki,
K.Tomita.
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Ref.
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Embo J, 2009,
28,
3353-3365.
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PubMed id
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Abstract
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The CCA-adding enzyme synthesizes the CCA sequence at the 3' end of tRNA without
a nucleic acid template. The crystal structures of class II Thermotoga maritima
CCA-adding enzyme and its complexes with CTP or ATP were determined. The
structure-based replacement of both the catalytic heads and
nucleobase-interacting neck domains of the phylogenetically closely related
Aquifex aeolicus A-adding enzyme by the corresponding domains of the T. maritima
CCA-adding enzyme allowed the A-adding enzyme to add CCA in vivo and in vitro.
However, the replacement of only the catalytic head domain did not allow the
A-adding enzyme to add CCA, and the enzyme exhibited (A, C)-adding activity. We
identified the region in the neck domain that prevents (A, C)-adding activity
and defines the number of nucleotide incorporations and the specificity for
correct CCA addition. We also identified the region in the head domain that
defines the terminal A addition after CC addition. The results collectively
suggest that, in the class II CCA-adding enzyme, the head and neck domains
collaboratively and dynamically define the number of nucleotide additions and
the specificity of nucleotide selection.
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