Poster abstracts

Poster number 122 submitted by Mengxuan Jia

Structural analysis of RNA in the gas phase using ion mobility coupled to native MS

Mengxuan Jia (Department of Chemistry and Biochemistry, The Ohio State University), Samantha Sarni (Department of Chemistry and Biochemistry, The Ohio State University), Andrew Norris (Department of Chemistry and Biochemistry, The Ohio State University), Edrick Choi (Department of Chemistry and Biochemistry, The Ohio State University), Venkat Gopalan (Department of Chemistry and Biochemistry, The Ohio State University), Vicki Wysocki (Department of Chemistry and Biochemistry, The Ohio State University)

Abstract:
Native mass spectrometry (MS) has emerged as a powerful bioanalytical tool to characterize proteins and protein complexes in the past few decades1,2. However, the application of native MS on RNA is limited for the following reasons. First of all, whether the RNA ions can maintain a native-like structure in the gas phase as protein ions do is still unclear. Research shows that the RNA ions might collapse in the gas phase3. Secondly, RNA refolding often requires a certain concentration of divalent metal ions, e.g. Mg2+. This non-volatile additive, Mg2+, would cause signal suppression and peak broadening which make the data hard to interpret. Thirdly, there is no RNA calibrant database for collision cross section (CCS) measurement from the commercialized traveling wave ion mobility MS. In this work, we optimized the instrument settings for the direct CCS measurement of two model RNAs(PDB 2PCV and 2DRB)3, tRNA Phe and its mutant4, in the gas phase by using drift tube ion mobility MS and compared the experimental CCS with the theoretical values. We also investigated the influence of charge state and the amount of Mg2+ titrated in using collision and surface induced unfolding profiles via on a traveling wave ion mobility MS. In conclusion, with proper conditions, the tested RNA retains its native-like structure in the gas phase.

References:
1. Boeri Erba, E. & Petosa, C. The emerging role of native mass spectrometry in characterizing the structure and dynamics of macromolecular complexes. Protein Sci. 24, 1176–1192 (2015).
2. Heck, A. J. R. Native mass spectrometry: a bridge between interactomics and structural biology. Nat. Methods 5, 927–933 (2008).
3. Devine, P. W. A. et al. Investigating the Structural Compaction of Biomolecules Upon Transition to the Gas-Phase Using ESI-TWIMS-MS. J. Am. Soc. Mass Spectrom. 28, 1855–1862 (2017).
4. Strulson, C. A., Boyer, J. A., Whitman, E. E. & Bevilacqua, P. C. Molecular crowders and cosolutes promote folding cooperativity of RNA under physiological ionic conditions. RNA 20, 331–347 (2014).

Keywords: Native MS, Ion mobility, RNA structure