Title: "Mechanical Anisotropy of PD-L1-Affibody Complex Revealed by Single-Molecule Force Spectroscopy and Multiscale Adhesion Analysis."
The mechanical anisotropy of therapeutic binder proteins, such as antibodies, presents a novel opportunity to enhance their therapeutic efficacy in biopharmaceutical applications. While the development of therapeutic binder proteins has primarily focused on achieving higher binding affinity in equilibrium conditions, the response of these proteins to external forces in dynamic physiological environments is not always correlated with their mechanostability under equilibrium. Here, Dr. Gomes and his team investigated the mechanostability of an Affibody protein bound to its target, programmed cell death ligand 1 (PD-L1), by analyzing the response of the PD-L1-Affibody interaction under force using atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS). By employing five different pulling geometries and combining experimental AFM-SMFS with steered molecular dynamics (SMD) simulations, The team observed distinct mechanistic responses and changes in the unbinding pathway depending on the pulling points. The team further investigated the adhesion of the PD-L1-Affibody complex under shear forces using spinning disk assay (SDA) to analyze multivalent and collective interactions at the microscale. Remarkably, the results obtained from AFM-SMFS, SMD simulations, and SDA were consistent, indicating a direct correlation between single-molecule mechanics and collective adhesion at realistic length scales. Dr. Gomes’ findings demonstrate that the mechanical properties of therapeutic binder proteins can be modulated by altering the pulling geometry, offering new optimization parameters for targeted drug delivery applications. Additionally, the team found that the equilibrium binding affinity of the PD- L1-Affibody complex was minimally affected by the conjugation points for payloads. Overall, the study provides insights into the mechanical anisotropy of protein complexes and highlights the potential for enhancing therapeutic efficiency by selecting the appropriate conjugation points for payloads based on optimized stability under force, while maintaining equilibrium properties.
