2yy8

Publication Abstract from PubMed

The conserved cytidine residue at position 56 of tRNA contributes to the maintenance of the L-shaped tertiary structure. aTrm56 catalyzes the 2'-O-methylation of the cytidine residue in archaeal tRNA, using S-adenosyl-L-methionine. Based on the amino acid sequence, aTrm56 is the most distant member of the SpoU family. Here, we determined the crystal structure of Pyrococcus horikoshii aTrm56 complexed with S-adenosyl-L-methionine at 2.48 A resolution. aTrm56 consists of the SPOUT domain, which contains the characteristic deep trefoil knot, and a unique C-terminal beta-hairpin. aTrm56 forms a dimer. The S-adenosyl-L-methionine binding and dimerization of aTrm56 were similar to those of the other SpoU members. A structure-based sequence alignment revealed that aTrm56 conserves only motif II, among the four signature motifs. However, an essential Arg16 residue is located at a novel position within motif I. Biochemical assays showed that aTrm56 prefers the L-shaped tRNA to the lambda form as its substrate.

Crystal structure and mutational study of a unique SpoU family archaeal methylase that forms 2'-O-methylcytidine at position 56 of tRNA.,Kuratani M, Bessho Y, Nishimoto M, Grosjean H, Yokoyama S J Mol Biol. 2008 Jan 25;375(4):1064-75. Epub 2007 Nov 17. PMID:18068186^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.