Protein mechanics and engineering at the single molecule level

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Elastomeric proteins are key elastic elements in a wide range of mechano-chemical machinery in cells, and can also function as structural materials of superb mechanical properties. Understanding the molecular design of elastomeric proteins is the key to understand the biophysical principles underlying various biological processes and to use these proteins as building blocks for the bottom-up construction of advanced materials and nanomechanical devices. We propose to combine single molecule atomic force microscopy with protein engineering, molecular dynamics simulations and traditional biophysical techniques to elucidate the physiochemical principles underlying the mechanical stability of proteins, to develop rational methodologies to design proteins with tunable mechanical properties and to engineer novel tandem-modular protein based biomaterials. We will focus our studies on a small protein GB1, one of the successful model proteins we screened for single protein mechanics studies. We will use single molecule AFM to measure the mechanical properties of proteins at the single molecule level and use site-directed mutagenesis to dissect the mechanical unfolding pathways and examine the roles of non-covalent interactions in determining the mechanical stability of proteins. Building upon our initial success in using engineered metal chelation to enhance the mechanical stability of GB1, we endeavor to develop the engineered metal chelation approach into a general and robust methodology for modulating the mechanical stability of diverse proteins in a rational and reversible fashion. Based on these well-characterized elastomeric proteins, we plan to engineer elastomeric protein-based biomaterials, such as chemically crosslinked hydrogels, to harness the mechanical properties engineered into individual elastomeric proteins in macroscopic biomaterials. These experimental efforts will serve as the first step towards using artificial elastomeric proteins as structural and functional building blocks for a variety of nanomechanical and material science applications.