Investigation of binding mechanism for human plasminogen Kringle 5 with its potential receptor vWA1 domain in Cochlin by bio-specific technologies and molecular dynamic simulation

Given the significant clinical potential of human plasminogen Kringle 5 on tumours, it is crucial to seek its receptors for a thorough comprehension of its physiological functions and mechanism. Eleven candidates have been screened out in our previous works. In the present work, we further inquired whether the candidate, von Willebrand factor type A domain 1 in coagulation factor C homology protein (abbr. vWA1), was a potential receptor of Kringle 5, and investigated their binding mechanism by bio-specific experiments, frontal affinity analysis (FA), and molecular dynamic simulation (MDS). After the potential was validated by bio-specific experiments, the FA results stated that vWA1 exhibited a strong interaction towards Kringle 5 in the proportion of 1:1 with the binding constant of 4.18 × 10⁴ L/mol. The MDS results showed that the binding was mainly driven by electrostatic and Van der Waals forces and occurred spontaneously, during which vWA1 and Kringle 5 mutually fit each other by conformational changing into more flexible and suitable structures including fluctuations for five loops and partial transformation into a random coil for α6-helix in vWA1. Moreover, lysine binding site Leu71-Tyr74 was speculated responsible for Kringle 5 in binding and Tyr72 to be the key amino acid residue. In short, this work not only confirmed vWA1 as a potential Kringle 5 receptor but also provided valuable information on the detailed binding, facilitating the application development of Kringle 5 in regulating immune or inhibiting tumour migration through vWA1.