Mechanical Stabilization of Proteins Due to Ligand Binding Using Magnetic Tweezers

Benjamin Delebreau, “Mechanical Stabilization of Proteins Due to Ligand Binding Using Magnetic Tweezers”
Mentors: Ionel Popa & Narayan Dahal, Physics

The mechanical unfolding of proteins is commonly measured using single molecule force spectroscopy techniques. Here, we use magnetic tweezers and hetero-covalent attachments to measure this unfolding with the ability to change the surrounding solution or solvent easily in order to assess binding of a ligand to its substrate. Protein L and the Talin rod domains, R7 and R8, are our two substrates of choice. Protein L is a bacterial protein with two binding sites for kappa-light chain antibody ligands. The R8 domain of Talin is known to bind a potential antitumor ligand, Deleted in Liver Cancer 1 (DLC1). HaloTag and Spytag were used on the ends of each molecular construct to tether the proteins. Magnetic tweezers are then able to expose the molecule to forces up to 100 pN and measure unfolding and refolding cycles. We find that ligand binding induces mechanical stabilization in both protein L and Talin R8 domains. These results open the way for screening new mechano-active drugs against bacterial infection and cancer.



  1. The presentation of this study was clear and straight forward. Each step was noted and described well, and your conclusions seemed to follow logically from the study. I would note that this presentation was designed for people who are already conversant in the subject of the study – which is fine, but limits the general public at such events as the UG Research Symposium from engaging it. This is where, obviously, if the event could have been held a live interaction with questions would have been fruitful. Some of the questions which come up for me are as follows:
    1. What do the results of this study lead to? What’s the next step?
    2. What are the real-world applications, short or long term, of this study?
    3. Why should I, as someone not highly knowledgeable of physics, care about this study?
    But, overall, an excellent job.

    1. Hi and thanks for your comments/questions! The novel mechanism used in bacteria attachment to antibodies when disrupting the immune response can present a platform for developing novel antibiotics. The study on talin and mechano-transduction explains how Deleted in Liver Cancer 1 (DLC1, which is also present in many more metastatic cancers) might work to inhibit the expansion of cells by preventing uncontrolled formations of focal adhesions. This study is relevant for everyone as it gives insight into developing novel antibiotics and cancer-suppressing drugs.

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