Filtering Disordered Protein Conformations by NMR Residual Dipolar Couplings

Area of Science:

• Biochemistry
• Structural Biology
• Computational Biology

Background:

• Intrinsically disordered regions (IDRs) play crucial roles in cell signaling but possess complex conformational landscapes.
• Characterizing IDR conformational space is challenging due to numerous similar-energy conformations.
• The Threading-Augmented interval Branch-and-Prune (TAiBP) method systematically enumerates protein conformations.

Purpose of the Study:

• To extend the TAiBP approach for describing IDR conformational landscapes using residual dipolar couplings (RDCs).
• To compare TAiBP-derived conformational descriptions with classical methods.
• To refine the analysis of IDR structure and dynamics.

Main Methods:

• Utilized Ramachandran diagram regions (from δ2D predictions) and secondary structure elements (from RDC and chemical shift index consensus) for conformation generation.
• Employed maximum-parsimony ensemble reweighting with non-negative least-squares (nnls) for RDC-based filtering.
• Integrated RDC filtering into the TAiBP assembly step to enhance resolution.

Main Results:

• The extended TAiBP approach successfully generated representative peptide conformations.
• RDC filtering refined the conformational landscape, leading to more localized secondary structure elements.
• The results showed general agreement with previously published findings, validating the enhanced method.

Conclusions:

• The enhanced TAiBP method provides a robust framework for characterizing IDR conformational landscapes with RDC data.
• This approach improves the accuracy and resolution of structural analysis for disordered proteins.
• The findings contribute to a better understanding of IDR function in biological processes like cell signaling.