High Affinity vs. Native Fibronectin in the Modulation of alpha v beta 3 Integrin Conformational Dynamics: Insights from Computational Analyses and Implications for Molecular Design

Understanding how binding events modulate functional motions of
multidomain proteins is a major issue in chemical biology. We address
several aspects of this problem by analyzing the differential dynamics
of alpha v beta 3 integrin bound to wild type (wtFN10, agonist) or high
affinity (hFN10, antagonist) mutants of fibronectin. We compare the
dynamics of complexes from large-scale domain motions to inter-residue
coordinated fluctuations to characterize the distinctive traits of
conformational evolution and shed light on the determinants of
differential alpha v beta 3 activation induced by different FN
sequences. We propose an allosteric model for ligand-based integrin
modulation: the conserved integrin binding pocket anchors the ligand,
while different residues on the two FN10's act as the drivers that
reorganize relevant interaction networks, guiding the shift towards
inactive (hFN10-bound) or active states (wtFN10-bound). We discuss the
implications of results for the design of integrin inhibitors.