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PDBsum entry 3wfs
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Transferase/RNA
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PDB id
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3wfs
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References listed in PDB file
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Key reference
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Title
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Translocation and rotation of tRNA during template-Independent RNA polymerization by tRNA nucleotidyltransferase.
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Authors
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S.Yamashita,
D.Takeshita,
K.Tomita.
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Ref.
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Structure, 2014,
22,
315-325.
[DOI no: ]
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PubMed id
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Abstract
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The 3'-terminal CCA (CCA-3' at positions 74-76) of tRNA is synthesized by
CCA-adding enzyme using CTP and ATP as substrates, without a nucleic acid
template. In Aquifex aeolicus, CC-adding and A-adding enzymes collaboratively
synthesize the CCA-3'. The mechanism of CCA-3' synthesis by these two enzymes
remained obscure. We now present crystal structures representing CC addition
onto tRNA by A. aeolicus CC-adding enzyme. After C₇₄ addition in an enclosed
active pocket and pyrophosphate release, the tRNA translocates and rotates
relative to the enzyme, and C₇₅ addition occurs in the same active pocket as
C₇₄ addition. At both the C₇₄-adding and C₇₅-adding stages, CTP is
selected by Watson-Crick-like hydrogen bonds between the cytosine of CTP and
conserved Asp and Arg residues in the pocket. After C₇₄C₇₅ addition and
pyrophosphate release, the tRNA translocates further and drops off the enzyme,
and the CC-adding enzyme terminates RNA polymerization.
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