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OCRE Domains of Splicing Factors RBM5 and RBM10: Tyrosine Ring‐Flip Frequencies Determined by Integrated Use of 1 H NMR Spectroscopy and Molecular Dynamics Simulations
Author(s) -
Martin Bryan T.,
Malmstrom Robert D.,
Amaro Rommie E.,
Wüthrich Kurt
Publication year - 2021
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.202000517
Subject(s) - nuclear magnetic resonance spectroscopy , spectroscopy , ring (chemistry) , molecular dynamics , chemistry , nmr spectra database , chemical shift , crystallography , tyrosine , hydrogen bond , spectral line , stereochemistry , computational chemistry , molecule , physics , biochemistry , organic chemistry , quantum mechanics , astronomy
The 55‐residue OCRE domains of the splicing factors RBM5 and RBM10 contain 15 tyrosines in compact, globular folds. At 25 °C, all 15 tyrosines show symmetric 1 H NMR spectra, with averaged signals for the pairs of δ‐ and ϵ‐ring hydrogens. At 4 °C, two tyrosines were identified as showing 1 H NMR line‐broadening due to lowered frequency of the ring‐flipping. For the other 13 tyrosine rings, it was not evident, from the 1 H NMR data alone, whether they were either all flipping at high frequencies, or whether slowed flipping went undetected due to small chemical‐shift differences between pairs of exchanging ring hydrogen atoms. Here, we integrate 1 H NMR spectroscopy and molecular dynamics (MD) simulations to determine the tyrosine ring‐flip frequencies. In the RBM10‐OCRE domain, we found that, for 11 of the 15 tyrosines, these frequencies are in the range 2.0×10 6 to 1.3×10 8 s −1 , and we established an upper limit of <1.0×10 6 s −1 for the remaining four residues. The experimental data and the MD simulation are mutually supportive, and their combined use extends the analysis of aromatic ring‐flip events beyond the limitations of routine 1 H NMR line‐shape analysis into the nanosecond frequency range.