Eukaryotic selenocysteine tRNA has the 9/4 secondary structure.
There are two secondary structure models for the eukaryotic selenocysteine (Sec) tRNA(Sec). One model, the 9/4 structure, was experimentally tested and possesses acceptor and T-stems with 9 and 4 bp, respectively [Sturchler et al., 1993; Hubert et al., 1998]. The other one, the 7/5 secondary structure with a bulge in the T-stem, was derived from theoretical calculation [Ioudovitch and Steinberg, 19991. In this report, we show more experimental results supporting the 9/4 secondary structure. Several tRNA(Sec) mutants, whose secondary structure can adopt only the 9/4 structure, were active for serylation and selenylation. Some mutants that cannot base-pair between positions 26 and 44 to provide the 6 bp anticodon stem were still active, inconsistent with the model by Steinberg. We also show that the orientation of the V-arm directly or indirectly influences the selenylation activity, and that the rigid 6 bp D-stem is important. Finally, we conclude that all tRNA(Sec) possess the 13 bp domain II made by the stacking of the colinear AA and T-stems, whether they present the 9/4 structure in Eukarya and Archaea or the 8/5 structure in bacteria.
Mizutani
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Faculty of Pharmaceutical Sciences, Nagoya City University, Japan. mizutani@phar.nagoya-cu.ac.jp
Goto
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D001483:Base Sequence; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012345:RNA, Transfer, Amino Acid-Specific / Q000737:chemistry* / Q000235:genetics; D012694:Serine / Q000737:chemistry
D012345:RNA, Transfer, Amino Acid-Specific; C036928:tRNA, selenocysteine-; D012694:Serine