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Acceptor stem and anticodon RNA hairpin helix interactions with glutamine tRNA synthetase
D J Wright1, S A Martinis, M Jahn
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Abstract:
The class I glutamine (Gln) tRNA synthetase interacts with the anticodon and acceptor stem of glutamine tRNA. RNA hairpin helices were designed to probe acceptor stem and anticodon stem-loop contacts. A seven-base pair RNA microhelix derived from the acceptor stem of tRNA(Gln) was aminoacylated by Gln tRNA synthetase. Variants of the glutamine acceptor stem microhelix implicated the discriminator base as a major identity element for glutaminylation of the RNA helix. A second RNA microhelix representing the anticodon stem-loop competitively inhibited tRNA(Gln) changing. However, the anticodon stem-loop microhelix did not enhance aminoacylation of the acceptor stem microhelix. Thus, transduction of the anticodon identity signal may require covalent continuity of the tRNA chain to trigger efficient aminoacylation.