The osmolyte TMAO stabilizes native RNA tertiary structures in the absence of Mg2+: evidence for a large barrier to folding from phosphate dehydration.

ABSTRACT: The stabilization of RNA tertiary structures by ions is well known, but the neutral osmolyte trimethylamine oxide (TMAO) can also effectively stabilize RNA tertiary structure. To begin to understand the physical basis for the effects of TMAO on RNA, we have quantitated the TMAO-induced stabilization of five RNAs with known structures. So-called m values, the increment in unfolding free energy per molal of osmolyte at constant KCl activity, are ∼0 for a hairpin secondary structure and between 0.70 and 1.85 kcal mol(-1)m(-1) for four RNA tertiary structures (30-86 nt). Further analysis of two RNAs by small-angle X-ray scattering and hydroxyl radical probing shows that TMAO reduces the radius of gyration of the unfolded ensemble to the same endpoint as seen in titration with Mg(2+) and that t

SUBMITTER: Lambert D 

PROVIDER: S-EPMC3001104 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature