HOW ACCURATELY AND PRECISELY CAN RNA STRUCTURE BE DETERMINED BY NMR

The great diversity of RNA biological functions has led to widespread interest in RNA structure. Advances in synthetic and spectroscopic tec hniques have recently allowed the extension of NMR methods of structur e determination to RNA structures of significant size and increased bi ological significance. However, it has not yet been established how ac curately and precisely RNA structure can be determined by NMR. The ext ensive simulations presented here establish credible limits on accurac y and precision of NMR-derived RNA structures and provide quantitative calibrations to evaluate new structures. Synthetic sets of NMR constr aints were generated from a crystallographically-derived ribozyme stru cture. The target structure was then redetermined using approximations and computational protocols derived from our experimental work. The r esults demonstrate that the structure of RNA molecules of at least 15, 000 Da can be determined with precision and accuracy of 1 to 1.5 Angst rom, comparable to values obtained for proteins of similar size. Most encouragingly, it is shown that larger, globular and biologically more important RNA structures can be determined with significantly better accuracy and precision than smaller, elongated structures investigated until now. (C) 1997 Academic Press Limited.