Our lab develops and uses cutting-edge techniques to study the physics of proteins under force. We combine single molecule force spectroscopy and bio-materials design with protein engineering, surface chemistry and computer programming. Our long-term goal is to understand how proteins operating under force use their folding state as a mechanical signal, and how this signal propagates from single molecule level to tissue and organs.
1. SINGLE MOLECULE NANO-MECHANICS
All processes in the human body rely to a large extent on the correct functioning of proteins. To perform their intended function, proteins need to fold in a specific 3D structure. Protein folding is one of the most complex physical process that combines short ranged hydrogen bonds between amino acids with the entropy of the polypeptide chain and interactions with the surrounding solvent molecules.
In our laboratory we use a revolutionary single molecule technique, developed in collaboration with Julio Fernandez from Columbia University and Jie Yan from National University of Singapore. This technique combines the long-term stability of magnetic tweezers with the specificity and strength of HaloTag covalent attachment to expose single protein constructs to mechanical perturbations identical to those experienced in vivo. This technique allows to directly sample the folding and unfolding process of proteins using force as a perturbation. We measure the end-to-end length of multi-domain protein constructs, which show under force unfolding and refolding transitions as step increments. This technique was successfully applied to study the mechanics of muscle proteins.
We are currently working together with Vali Raicu from UWM on developing a FRET/magnetic tweezers setup that would add a new dimension to our measurements. Using fluorescent tags, we plan to monitor the binding and unbinding of different reaction partners to single proteins under force.
2. BIO-INSPIRED ENGINEERING
Another aim of our laboratory is to develop “smart” bio-inspired materials, with possible biomedical applications for tissue engineering, drug delivery and bio-sensors. We use chemical cross-linking of engineered multi-protein constructs to synthesize protein hydrogels. These gels have remarkable properties and follow the measured unfolding mechanics of proteins measured with single molecule techniques. We have constructed an instrumental setup which allows us to measure the mechanical response of protein hydrogels under constant force conditions. Combining this technique with optical microscopy will allow us to monitor the complete structural transformation of polyprotein hydrogels. Furthermore, in collaboration with members of the BioXFEL group at UWM, we plan to harvest the power of X-ray to determine the structure and conformational changes that proteins inside hydrogels undergo when exposed to mechanical perturbations.