Biography
We are involved in structural studies on the assembly and function of actin-containing thin filaments in muscle and non-muscle cells. Our principal goal is to analyze and elucidate the mechanisms of thin filament-linked regulation of muscle contraction and cytoskeletal remodeling. To accomplish this goal, we use a combination of molecular biology, electron microscopy, electron tomography, image reconstruction and computational tools such as molecular dynamics protocols to better understand the interactions and dynamics of protein components of isolated and reconstituted thin filaments. Studies on mutants are carried out to elucidate abnormal filament function in disease processes. We have an excellent track record in successfully educating graduate and post-doctoral students in the application of the state-of-the-art techniques that we use. In particular, we have trained students with backgrounds in biological and biochemical sciences to be fearless about the challenge of performing sophisticated biophysical approaches, and, conversely, teaching students with background in physical and computational sciences to understand the biomedical underpinnings of our work. This dual process of training students with these diverse backgrounds in one laboratory setting is synergistic. As a sign of our success: of the 16 papers that have been published by us between 2018 and now (2021), 14 were co-authored by 8 different current or former post-doctoral fellows and graduate students from my laboratory.
Our laboratory was the first to directly visualize the steric-blocking mechanism of muscle regulation by identifying the positions assumed by tropomyosin on actin in the presence and the absence of Ca2+ using cryo-electron microscopy and negative staining. We also have demonstrated that during muscle activation tropomyosin moves away from myosin cross-bridge binding sites on actin in two highly cooperative steps, one induced by Ca2+ binding to troponin and a second induced by the binding of myosin to actin. Our laboratory is continuing the above-mentioned studies to obtain even greater resolution of the processes involved. At the same time, we are investigating the structural organization of troponin on thin filaments and the changes it undergoes on binding of Ca2+. We have also been engaged in studies on the structural interactions of other actin binding proteins including α-actinin, myosin binding protein-C, caldesmon, calponin, cortactin, filamin and native and mutant dystrophin, namely proteins that play important roles in the organization of the cytoskeleton in striated and smooth muscles as well as in non-muscle cells. (03/17/2021)