Molecular Dynamics Analysis of Self and Microbial Peptides Bound to HLA-B27: A Multi-Parameter Framework

Abstract

Molecular mimicry between pathogen-derived and self-peptides shown by MHC molecules is one of the critical mechanisms in the pathophysiology of autoimmune diseases. Numerous studied has been conducted in this field to identify sequence similarity, but evaluating structural and dynamic similarity, systematic computational frameworks remain limited. Therefore, we created an automated multi-parameter molecular dynamics analysis workflow and used it to compare three peptides (KP1, KP2, and KP3) generated from Klebsiella pneumoniae bound to HLA-B class protein with one human self-peptide (Annexin-derived, ANX). We assessed six complementing parameters using one microsecond-scale MD simulation: radius of gyration (Rg), solvent-accessible surface area (SASA), hydrogen bonding dynamics, MM-GBSA binding free energy, root mean square fluctuation (RMSF), and root mean square deviation (RMSD) to understand time-dependent structural and dynamic behaviour of all the peptide-HLA-B complex. Additionally, hydrogen bond occupancy and molecular mechanics generalised Born surface area (MM-GBSA) binding free energy calculations were performed to provide a more comprehensive assessment of complex stability. Our analysis suggests that KP1 exhibits structural features consistent with molecular mimicry, maintaining conformational stability, surface exposure, and interaction patterns comparable to ANX. In contrast, KP2 showed reduced stability, characterised by higher RMSD values and substantial hydrogen bond loss, whereas KP3 displayed intermediate behaviour, with relatively favourable energetics but noticeable conformational variability. Overall, the multi-parameter framework enabled differentiation among the candidate peptides based on combined structural, dynamic, and energetic properties. The workflow can be adapted for the analysis of larger peptide datasets and may provide a systematic approach for investigating potential autoimmune-relevant molecular mimics in microbial proteomes, with required adjustments according to the system.