Pressure Effects on the Conformational Transitions of tRNALys3

Abstract

It has been reported that pressure leads to disruption of RNA structure. However, the specific effects of pressure on RNA structures and the mechanism by which pressure destabilizes RNA tertiary structure are not well-understood. In particular, the role played by ions and water molecules in pressure perturbation of RNA remains unclear. Our study focuses on the roles of ions and hydration in the pressure-induced conformational transitions of tRNA. Our preliminary results using 2D 15N-1H HSQC NMR of the imino groups of Guanine and Uridine residues on labeled tRNALys3 demonstrate pressure-induced changes in tRNA tertiary structure above 1000 bar in both stems and loops of the tRNA. Addition of magnesium ions significantly inhibits pressure-induced structural changes, specifically in the Acceptor stem, Anti-codon stem, T-stem and T-loop, as evidenced by NMR experiments. High-pressure SAXS experiments revealed that the disrupted tRNA remains fairly compact, arguing against pressure-induced complete unfolding.