Structure‐Dynamics‐Function Relationships of Disintegrins in Integrin Recognition

Integrins are the major cell surface receptors for cells to interact with extracellular matrix proteins and play an important role in cytoskeleton reorganization and signal transduction. Disintegrins are potent integrin inhibitors found in snake venoms. Depending on the size and the number of cysteines, they can be classified into small, medium, long, and dimeric disintegrins. To study structure and functional relationships of short and medium disintegrins, we expressed rhodostomin (Rho), a 68‐residue disintegrin with six disulfide bonds, and echistatin (Ech), a 49‐residue disintegrin with four disulfide bonds, in Pichia pastoris as the model proteins. The analysis of cell adhesion assay showed that Rho mutant containing ARGDDM sequences in the RGD loop and NPHKGPAT sequence in the C‐terminus exhibited 14.4‐, 4.1‐, and 2.33‐folds decrease in inhibitory activity to integrins £\IIb£]3, £\v£]3 and £\5£]1, respectively. Backbone dynamics analysis showed that their similar dynamics properties on the RGD motif. In contrast, the C‐terminal region of Rho is more flexible of that of Ech. This suggests that the dynamics properties of the C‐terminus of disintegrins also play a crucial role in determining their affinity and selectivity to integrins.