Lincoln Scott - RNA helical packing in solution: NMR structure of a 30 kDa GAAA tetraloop-receptor complex.

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      Publication Details (including relevant citation   information):

      J Mol Biol. 2005   Aug 12;351(2):371-82.


      Tertiary interactions are critical for proper RNA folding and   ribozyme catalysis. RNA tertiary structure is often condensed   through long-range helical packing interactions mediated by   loop-receptor motifs. RNA structures displaying helical packing   by loop-receptor interactions have been solved by X-ray   crystallography, but not by NMR. Here, we report the NMR   structure of a 30 kDa GAAA tetraloop-receptor RNA complex. In   order to stabilize the complex, we used a modular design in which   the RNA was engineered to form a homodimer, with each subunit   containing a GAAA tetraloop phased one helical turn apart from   its cognate 11-nucleotide receptor domain. The structure   determination utilized specific isotopic labeling patterns (2H,   13C and 15N) and refinement against residual dipolar couplings.   We observe a unique and highly unusual chemical shift pattern for   an adenosine platform interaction that reveals a spectroscopic   fingerprint for this motif. The structure of the GAAA   tetraloop-receptor interaction is well defined solely from   experimental NMR data, shows minor deviations from previously   solved crystal structures, and verifies the previously inferred   hydrogen bonding patterns within this motif. This work   demonstrates the feasibility of using engineered homodimers as   modular systems for the determination of RNA tertiary   interactions by NMR.

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