Mapping Charge Interactions in Intrinsically Disordered Proteins

Area of Science:

• Biophysics
• Computational Biology
• Protein Science

Background:

• Intrinsically disordered proteins (IDPs) are crucial for cellular functions but challenging to study due to their dynamic nature.
• Electrostatic interactions significantly influence IDP behavior, yet quantitative modeling is complex due to factors like charge patterning and screening.

Purpose of the Study:

• To develop analytically tractable models for predicting residue-pair distances in IDPs.
• To account for sequence-specific charge arrangements and salt concentration effects on IDP conformations.

Main Methods:

• Developed quantitative polymer models incorporating charge patterning and counterion condensation.
• Validated models against extensive single-molecule Förster resonance energy transfer (FRET) data for various charged IDPs.
• Systematically tested model predictions across different salt concentrations and labeling positions.

Main Results:

• The models accurately predict ensemble average distances between residue pairs in IDPs.
• The models capture the effects of counterion condensation and effective charge on protein structure.
• Detailed intrachain distance maps for IDPs can be predicted using these models.

Conclusions:

• Analytical models provide a valuable, computationally efficient complement to simulations for studying IDPs.
• These models offer fundamental insights into the electrostatic interactions governing IDP conformational distributions.
• The developed models can predict how sequence and salt concentration modulate IDP structure and dynamics.