Structural basis of potent and selective integrins α5β1 and αvβ3‐specific disintegrins

Integrins are αβ heterodimeric transmembrane receptors that mediate cell‐cell and cell‐extracellular matrices interactions. Integrins αvβ3 and α5β1 are important therapeutic targets in angiogenesis and tumor metastasis. In this study we used rhodostomin (Rho), a disintegrin containing a 48 PRGDMP 53 motif, as a scaffold to design integrins‐specific disintegrins. Our functional analysis showed that the alternations of the RGD loop of Rho affect its binding affinities and specificities to integrins. The P48A mutation on Rho increased a 5‐fold affinity to integrin α5β1, and G50L mutant can selectively inhibit integrin αvβ3. Using nuclear magnetic resonance (NMR) spectroscopy and protein docking to study how the mutations affect their interactions with integrins. We found that the P48A mutation did not affect its tertiary structure and interactions with integrin α5β1. In contrast, backbone dynamics analysis showed that the major differences between Rho and its P48A mutant were found from chemical exchange rate (R ex ) and internal effective correlation time (τ e ) of the RGD motif. Further, we found structural difference for the G50L mutant. A binding pocket on integrin αvβ3 but not αIIbβ3 could accommodate the longer side‐chain of L50 residue. These findings demonstrate that structure and dynamics properties of disintegrins are important for their affinity and specificity to integrins.