SAMOP 2021 – scientific programme

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MO: Fachverband Molekülphysik

MO 6: Ultrafast

MO 6.2: Talk

Thursday, September 23, 2021, 14:15–14:30, H2

Ultrafast 2D-IR spectroscopy probes tRNA-Magnesium contact ion pairs — •Jakob Schauss, Achintya Kundu, Benjamin P. Fingerhut, and Thomas Elsaesser — Max Born Institute for Nonlinear Optics and Short-Pulse Spectroscopy, Berlin, Germany

The negative charge of nucleic acids makes them susceptible to interactions with their surrounding water shell and the ions embedded within. Magnesium ions in particular are known to strongly interact with RNA molecules, for example in the folding of functional RNA from an elongated chain into the native, condensed form. The interactions that play a role in the folding process are highly debated, partially due to the lack of non-invasive probes on the microscopic level.

Here, we use femtosecond 2D-IR spectroscopy of phosphate backbone vibrations to investigate the formation of transfer RNA/Mg²⁺ contact ion pairs (CIP). Phosphate vibrations have been shown to sense changes in the water environment upon RNA melting [1] and report on CIP formation in model systems [2]. The experimental results on tRNA agree well with molecular dynamics simulations that show stabilization of tRNA tertiary structure through contact ion pairs. Particularly in highly congested regions of the tRNA, the magnesium ions are instrumental in efficiently compensating the high negative charge density [3].
[1] A. Kundu et al.: J. Phys. Chem. B, 124, 2132-2138 (2020)
[2] J. Schauss et al., J. Phys. Chem. Lett. 10, 6281-6286 (2019)
[3] J. Schauss et al.: J. Phys. Chem. B, 125, 740-747 (2021)