Sensitivity-Enhanced Four-Dimensional Amide-Amide Correlation NMR Experiments for Sequential Assignment of...

Area of Science:

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

Background:

• Proline residues are common in intrinsically disordered proteins (IDPs).
• Assigning NMR resonances in proline-rich IDPs is difficult due to low chemical shift dispersion.
• This challenge hinders structural and functional studies of these important proteins.

Purpose of the Study:

• To develop novel, sensitivity-enhanced 4D NMR experiments.
• To overcome the limitations of standard NMR techniques for proline-rich IDPs.
• To improve the assignment of amide resonances in complex protein systems.

Main Methods:

• Development of 4D NMR experiments correlating consecutive (NHi-1, NHi) or proline-flanking (NHi-2, NHi) amide resonances.
• Incorporation of two unconventional coherence order-selective (COS) transfers for sensitivity enhancement.
• Application of the method to proline-rich regions of SLP-65 and α-synuclein.

Main Results:

• Achieved a maximum 2-fold sensitivity enhancement using COS transfers.
• Successfully assigned 99% of nonprolyl amide resonances in SLP-65 and 92% in α-synuclein.
• Demonstrated the method's effectiveness for large proline-rich IDPs.

Conclusions:

• The proposed 4D NMR experiments significantly improve resonance assignment in proline-rich IDPs.
• This technique provides a robust solution for studying the structure and dynamics of challenging protein targets.
• Enhanced NMR sensitivity facilitates deeper insights into the function of intrinsically disordered proteins.