SPEADI: Accelerated Analysis of IDP-Ion Interactions from MD-Trajectories.

Area of Science:

• Biochemistry
• Computational Biology
• Structural Biology

Background:

• Intrinsically Disordered Proteins (IDPs) lack stable 3D structures, making their function highly dependent on environmental conditions.
• Traditional Radial Distribution Functions (RDFs) average structural data, which can obscure crucial dynamic information for IDPs.
• Understanding the dynamic chemical environment is key to elucidating IDP function and malfunction.

Purpose of the Study:

• To develop and introduce a novel method, Time-Resolved Radial Distribution Function (TRRDF), for characterizing the dynamic environments of IDPs.
• To assess the reliability of TRRDF for analyzing the local chemical surroundings of IDPs, overcoming limitations of averaged RDFs.
• To investigate the role of ion-residue interactions in the structural dynamics and function of specific IDPs.

Main Methods:

• Implementation of TRRDF within the open-source Python package SPEADI.
• Application of SPEADI and TRRDF to analyze Molecular Dynamics (MD) simulations of Intrinsically Disordered Proteins (IDPs).
• Characterization of the dynamic distribution of ions around Alpha-Synuclein (AS) and Humanin (HN), including selected mutants.

Main Results:

• TRRDF successfully characterizes the dynamic environments around IDPs, providing more reliable information than traditional averaged RDFs.
• Analysis revealed significant dynamic changes in ion distribution influenced by IDP structural variability.
• Local ion-residue interactions were identified as critical determinants of IDP structure and behavior.

Conclusions:

• TRRDF is a powerful tool for studying the dynamic nature of IDP environments.
• Dynamic ion-residue interactions significantly influence the conformational ensembles and functions of IDPs.
• The SPEADI package offers a valuable resource for researchers investigating IDP dynamics.