Deeper Insight of the Conformational Ensemble of Intrinsically Disordered Proteins

Area of Science:

• Biophysics
• Structural Biology
• Protein Science

Background:

• Intrinsically disordered proteins (IDPs) lack stable tertiary structures, existing as dynamic conformational ensembles (CoE).
• Understanding the heterogeneity of IDP structures is crucial for elucidating their diverse biological functions.
• Current methods often combine low-resolution experimental techniques with computational simulations to study IDP CoE.

Purpose of the Study:

• To develop a method for decomposing the conformational ensemble (CoE) of intrinsically disordered proteins (IDPs) based on their radius of gyration (Rg).
• To investigate the secondary structure propensities of individual conformers within the IDP ensemble.
• To provide a more detailed understanding of the structure-function relationship in IDPs.

Main Methods:

• Utilized histatin 5, a well-characterized IDP, as a model system.
• Acquired average intensity curves using small-angle X-ray scattering (SAXS).
• Integrated SAXS data with all-atom, explicit-water molecular dynamics (MD) simulations and decomposed the intensity curve by Rg values.

Main Results:

• Successfully decomposed the conformational ensemble (CoE) of histatin 5 based on radius of gyration (Rg) values.
• Investigated the secondary structure propensities associated with different Rg-defined conformers.
• Demonstrated the utility of combining SAXS with MD simulations for detailed CoE analysis.

Conclusions:

• The developed approach offers a novel way to dissect the conformational ensemble of IDPs.
• This method provides valuable information on individual conformers and their structural characteristics.
• The findings contribute to a deeper understanding of IDP structure-function relationships at a granular level.