The minimal tRNA: Unique structure of Ascaris suum mitochondrial tRNA_UCU^Ser having a short T arm and lacking the entire D arm

The tertiary structure of Ascaris suum mitochondrial tRNA_UCU^Ser was examined by nuclear magnetic resonance analysis using its transcript, since tRNA_UCU^Ser, lacking the D arm and possessing a truncated T arm, is the shortest of all the known tRNAs. Most basepairs in the proposed secondary structure of tRNA_UCU^Ser were shown to exist, but the connector region comprising the truncated D loop and the extra loop was flexible. This flexibility, would enable adjustment of the mutual distance between the 3′-terminus and the anticodon consistent with that of usual tRNAs. Thus, tRNA^SerUCU appears to function in a similar way to that of usual tRNAs in the ribosome.