Thomas Elsässer | Max-Born-Institut | Berlin, Germany
Scientific Talks, Session VII | Tuesday, September 13 | 16:00 – 16:30
Solvation of charged species plays a fundamental role for the structure and function of hydrated biomolecules . The electric dipole moment of water molecules gives rise to strong electric fields in the liquid which, due to thermally activated molecular motions, fluctuate in a time range from tens of femtoseconds to several picoseconds. At the surface of biomolecules, the electric field strength reaches values of up to 100 MV/cm with fluctuation amplitudes of several tens of MV/cm . The formation of stable tertiary RNA and DNA structures with negatively charged phosphate groups in their backbone requires a balance of repulsive and attractive electric interactions, mediated by ions and the water shell. Vibrational excitations of the phosphate groups are sensitive noninvasive probes of local hydration geometries and related electric fields .
This talk focuses on dynamic electric interactions in different hydrated RNA systems [4,5]. Femtosecond two-dimensional infrared spectroscopy and in-depth molecular dynamics simulations reveal a prominent role of phosphate-magnesium contact ion pairs and their local water environment in stabilizing RNA structure. Results are presented for short RNA duplexes  and the tertiary cloverleaf structure of transfer RNA . The spectroscopic results and a theoretical analysis at the molecular level  give quantitative insight in electric interactions at the RNA-water interface.
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 E. M. Bruening, J. Schauss, T. Siebert, B. P. Fingerhut, T. Elsaesser, J. Phys. Chem. Lett. 9, 583 (2018).
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 B. P. Fingerhut, J. Schauss, A. Kundu, T. Elsaesser, Biophys. J. 120, 5322 (2021).