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Base Pairing within the ψ3239-Modified Anticodon Arm of Escherichia coli tRNAPhe

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journal contribution
posted on 13.12.2006, 00:00 by Izabela Tworowska, Edward P. Nikonowicz
The base−base hydrogen bond interactions of the ψ3239-modified anticodon arm of Escherichia coli tRNAPhe have been investigated using heteronuclear NMR spectroscopy. ψ32 and ψ39 were enzymatically introduced into a [13C,15N]-isotopically enriched RNA sequence corresponding to the tRNAPhe anticodon arm. Both the ψ32−A38 and A31−ψ39 nucleotide pairs form Watson−Crick base pairing schemes and the anticodon nucleotides adopt a triloop conformation. Similar effects were observed previously with D2-isopentenyl modification of the A37 N6 that also is native to the tRNAPhe anticodon arm. These results demonstrate that the individual modifications are not sufficient to produce the 32−38 bifurcated hydrogen bond or the U-turn motifs that are observed in crystal structures of tRNAs and tRNA-protein complexes. Thus the formation of these conserved structural features in solution likely require the synergistic interaction of multiple modifications.

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