Nuclear Overhauser effect study and assignment of D stem and reverse-Hoogsteen base pair proton resonances in yeast tRNA^Asp

Abstract

Nuclear Overhauser effects (NOEs) in yeast tRNA^AsP were found for all four GU and GΦ base pairs. NOEs of both reverse-Hoogsteen pairs were identified by comparison with a purine C8 deuterated sample. Several NOEs involving these resonances were also found which are clearly between single protons on adjacent base pairs. These interbase NOEs, combined with the assumption of reasonable similarity between the structure of yeast tRNA^Asp and that of yeast tRNA^Pne, lead to unambiguous assignment of many resonances including all the ring NH and C2 protons in the D stem. The stability of the stem at 28°C, as recently deduced by Moras et al (Nature 288 669-674), from x-ray diffraction is confirmed. Assignments of the ring NH resonances of T54-A58 and of a GΦ pair are made for the first time.