Study of the Mechanics of Proteins in the Presence of their Natural Ligands

Talin is a cytoskeletal protein that plays a critical role in mechano-transduction, and its misregulation is thought to play a critical role in cancer metastasis. Talin is an essential part of the linkage that cells form between their cytoskeleton and the surroundings (extracellular matrix) and works like a mechanical computer, governing adhesion and migration. Here we are investigating the mechanical response of R7R8 rod domains of talin in the presence of different binding partners such as RIAM, vinculin and DLC1. RIAM brings talin to the plasma membrane and activates cells. Vinculin reinforces focal adhesions. The role of DLC1 is unknown, but it was shown to have tumor suppressor activity. These partners are mutually exclusive, with RIAM and DLC1 binding to the folded state of R8 and vinculin binding to the unfolded state of both R7 and R8. We engineered constructs with these proteins and measured the mechanical response of the talin R7R8 rod domains in the presence and absence of its ligands using magnetic tweezers. We find that both RIAM and DLC1 lock talin R8 in a folded conformation, preventing vinculin binding and that DLC1 has higher affinity than RIAM. Our measurements show a new mechanism for DLC1 as a tumor suppressor