Microsecond Dynamics in Ubiquitin Probed by Solid-State 15N NMR Spectroscopy R1ρ Relaxation Experiments under Fast MAS (60–110 kHz)

5 years ago

Microsecond Dynamics in Ubiquitin Probed by Solid-State 15N NMR Spectroscopy R1ρ Relaxation Experiments under Fast MAS (60–110 kHz)

Matthias Ernst, Riccardo Cadalbert, Alons Lends, Susanne Penzel, Beat H. Meier, Nils-Alexander Lakomek

15N R1ρ relaxation experiments in solid-state NMR spectroscopy are sensitive to timescales and amplitudes of internal protein motions in the hundreds of nano- to microsecond time window, which is difficult to probe by solution-state NMR spectroscopy. By using 15N R1ρ relaxation experiments, a simplified approach to detect low microsecond protein dynamics is described and residue-specific correlation times are determined from the ratio of 15N R1ρ rate constants at different magic angle spinning frequencies. Microcrystalline ubiquitin exhibits small-amplitude dynamics on a timescale of about 1 μs across the entire protein, and larger amplitude motions, also on the 1 μs timescale, for several sites, including the β1–β2 turn and the N terminus of the α helix. According to the analysis, the microsecond protein backbone dynamics are of lower amplitude than that concluded in previous solid-state NMR spectroscopy studies, but persist across the entire protein with a rather uniform timescale of 1 μs. Just relax! Solid-state 15N R1ρ NMR relaxation experiments under fast magic angle spinning (MAS; 60–110 kHz) are used to investigate the internal backbone dynamics in microcrystalline ubiquitin (see figure). Small-amplitude backbone dynamics across the entire protein are found on a timescale of about 1–2 μs and larger amplitude motion is found for several sites, including the first β1–β2 turn and N terminus of the α helix on the same 1–2 μs timescale.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201701738