William J. Lehman, PhD
|Institution||Boston University School of Medicine|
|Department||Physiology & Biophysics|
|Address||72 E. Concord St Instructional (L)|
Boston MA 02118
|Title||Graduate Faculty (Primary Mentor of Grad Students)|
|Institution||Boston University School of Medicine, Division of Graduate Medical Sciences|
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 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 better understand 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 (my own experience) to be fearless about the challenge of carrying out 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 19 papers that have been published by us since 2007, 12 were co-authored by 5 different post-doctoral fellows and by 3 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 are also engaged in studies on the structural interactions of other actin binding proteins including a-actinin, 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.
- Electron Microscopy
- Molecular Dynamics
- muscle regulation
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