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PDBsum entry 4jal
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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 tRNA recognition mechanism of the minimalist spout methyltransferase, Trml.
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Authors
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R.J.Liu,
M.Zhou,
Z.P.Fang,
M.Wang,
X.L.Zhou,
E.D.Wang.
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Ref.
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Nucleic Acids Res, 2013,
41,
7828-7842.
[DOI no: ]
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PubMed id
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Abstract
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Unlike other transfer RNAs (tRNA)-modifying enzymes from the SPOUT
methyltransferase superfamily, the tRNA (Um34/Cm34) methyltransferase TrmL lacks
the usual extension domain for tRNA binding and consists only of a SPOUT domain.
Both the catalytic and tRNA recognition mechanisms of this enzyme remain
elusive. By using tRNAs purified from an Escherichia coli strain with the TrmL
gene deleted, we found that TrmL can independently catalyze the methyl transfer
from S-adenosyl-L-methionine to and isoacceptors without the involvement of
other tRNA-binding proteins. We have solved the crystal structures of TrmL in
apo form and in complex with S-adenosyl-homocysteine and identified the cofactor
binding site and a possible active site. Methyltransferase activity and
tRNA-binding affinity of TrmL mutants were measured to identify residues
important for tRNA binding of TrmL. Our results suggest that TrmL functions as a
homodimer by using the conserved C-terminal half of the SPOUT domain for
catalysis, whereas residues from the less-conserved N-terminal half of the other
subunit participate in tRNA recognition.
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