Water-Protein Interactions Coupled with Protein Conformational Transition

Area of Science:

• Biophysics
• Structural Biology
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Protein conformational fluctuations are vital for biological functions.
• The role of dynamic changes in protein hydration during conformational transitions remains incompletely understood.

Purpose of the Study:

• To investigate pressure-induced alterations in water-to-amide proton exchange dynamics in proteins.
• To elucidate the relationship between protein conformation, hydration, and hydrogen bond stability.

Main Methods:

• Utilized a phase-modulated clean chemical exchange NMR approach.
• Applied pressure perturbation up to 250 MPa to induce conformational changes in ubiquitin.
• Monitored sub-second time scale water-to-amide proton exchange rates.

Main Results:

• Observed significant increases in proton exchange rates for specific residues (32-35, 40-41, 71) in ubiquitin at 250 MPa.
• These changes correlate with the transition from the native (N1) to an alternative (N2) conformation.
• The results suggest destabilization of backbone hydrogen bonds and increased solvent accessibility in the N2 conformation.

Conclusions:

• Phase-modulated clean chemical exchange NMR combined with pressure perturbation is effective for studying protein dynamics.
• This technique facilitates the investigation of more open and hydrated protein structures.
• Pressure-induced conformational changes in ubiquitin involve significant alterations in hydration and hydrogen bonding patterns.