In vivo, cells are constantly subject to mechanical forces. The ability of cells to both sense their environment and exert forces are critical to numerous biological processes including cell migration, cell adhesion, and the maintenance of cell shape and function. Mechanosensing in particular, is essential for bone regeneration, wound healing, and the formation of a normal vascular endothelium. Both the capacity to sense forces and transduce proportional signals to the cell are attributed cell surface adhesion proteins.

We are determining how these protein machines transduce mechanical signals in the cell, and generate proportional signals that alter cell functions. The use of sensitive instruments to exert defined forces on protein bonds also enables us to quantify cell response to defined mechanical stimuli. We determine the strengths of single molecular bonds, and precisely measure the range and magnitude of intermolecular forces. One of our main objectives is to establish how molecular structure determines the mechanical strength and dynamics of protein bonds. In addition, we are using live cell fluorescence biosensors that directly report how force on protein bonds trigger intracellular signals.

To gain atomic level information on the molecular contacts that stabilize protein bonds, we complement our nanomechanics measurements with steered molecular dynamics simulations. We use these simulations to identify critical side chain interactions that stabilize the protein bonds under force. We experimentally verified predictions based on the simulations, using a combination of site directed mutagenesis and molecular force measurements. This comprehensive approach, which combines experiment, theory, and biomolecular engineering, provides us with unique insight into the structural basis of biological nanomachines and their impact on biological function.