کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2187603 | 1096128 | 2008 | 12 صفحه PDF | دانلود رایگان |
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 Å resolution. aTrm56 consists of the SPOUT domain, which contains the characteristic deep trefoil knot, and a unique C-terminal β-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 λ form as its substrate.
Journal: Journal of Molecular Biology - Volume 375, Issue 4, 25 January 2008, Pages 1064–1075