Understanding binding epitopes involved in protein–protein
interactions and accurately determining their structure are long-standing
goals with broad applicability in industry and biomedicine. Although
various experimental methods for binding epitope determination exist,
these approaches are typically low throughput and cost-intensive.
Computational methods have potential to accelerate epitope predictions;
however, recently developed artificial intelligence (AI)-based methods
frequently fail to predict epitopes of synthetic binding domains with
few natural homologues. Here we have developed an integrated method
employing generalized-correlation-based dynamic network analysis on
multiple molecular dynamics (MD) trajectories, initiated from AlphaFold2Multimer
structures, to unravel the structure and binding epitope of the therapeutic
PD-L1:Affibody complex. Both AlphaFold2 and conventional molecular
dynamics trajectory analysis were ineffective in distinguishing between
two proposed binding models, parallel and perpendicular. However,
our integrated approach, utilizing dynamic network analysis, demonstrated
that the perpendicular mode was significantly more stable. These predictions
were validated using a suite of experimental epitope mapping protocols,
including cross-linking mass spectrometry and next-generation sequencing-based
deep mutational scanning. Conversely, AlphaFold3 failed to predict
a structure bound in the perpendicular pose, highlighting the necessity
for exploratory research in the search for binding epitopes and challenging
the notion that AI-generated protein structures can be accepted without
scrutiny. Our research underscores the potential of employing dynamic
network analysis to enhance AI-based structure predictions for more
accurate identification of protein–protein interaction interfaces.