4JAK: Crystal Structure Of Trna (um34/cm34) Methyltransferase Trml From Escherichia Coli

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.
PDB ID: 4JAKDownload
MMDB ID: 112250
PDB Deposition Date: 2013/2/18
Updated in MMDB: 2013/08
Experimental Method:
x-ray diffraction
Resolution: 2  Å
Source Organism:
Similar Structures:
Biological Unit for 4JAK: dimeric; determined by author and by software (PISA)
Molecular Components in 4JAK
Label Count Molecule
Proteins (2 molecules)
tRNA (Cytidine(34)-2'-o)-methyltransferase(Gene symbol: trmL)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB