BME Distinguished Seminar Series with Steven Chu: What can be learned by tracking the motion of cargos due to dynein in live cells with millisecond and microsecond time resolution and sub-nanometer spatial resolution

Presenter: Professor Steven Chu, William R. Kenan, Jr. Professor of Physics, of Molecular and Cellular Physiology, and of Energy Science and Engineering at Stanford University, the 1997 Nobel Prize laureate in laser cooling and trapping of atoms and former U.S. Secretary of Energy

We have measured to the transport of molecular cargos in neuronal cells with 1 millisecond time resolution and 4 nm spatial resolution. Our development of very bright optical probes enabled the long-term single tracking of molecular cargos. Our probes allowed individual molecular steps to be resolved at cellular ATP concentrations (three orders of magnitude higher than the in vitro
studies), and led to a new, detailed quantitatively falsifiable chemo-mechanical model where two ATP molecules are hydrolyzed sequentially. A model of how this motor cleverly uses thermal fluctuations to produce move molecular cargos will be discussed.
More recently, we have improved the tracking resolution to ~1 us time resolution with 0.3 nm spatial resolution to test the predictions of our new model of how dynein operates. The first results of this new work, and what it can tell us about the molecular biology and biophysics of this motor will be discussed.

Steven Chu is the William R. Kenan, Jr. Professor of Physics, of Molecular and Cellular Physiology, and of Energy Science and Engineering at Stanford University. He received the 1997 Nobel Prize in Physics for laser cooling and trapping of atoms. Other contributions include the first optical tweezers manipulation of biomolecules, precision atom interferometry based on optical pulses of light, and single molecule FRET of biomolecules tethered to surfaces. He is now developing and applying new methods in molecular biology and medical imaging, materials science, and batteries. Previously he was U.S. Secretary of Energy, where he began ARPA-E, the Energy Innovation Hubs, and was tasked by President Obama to help BP stop the Macondo Oil spill. Previously, he was Director of Lawrence Berkeley National Laboratory and Professor of Physics and Applied Physics at Stanford, and helped initiate Bio-X, which linked the physical and biological sciences with engineering and medicine. Before Stanford, he was a department head at Bell
Laboratories. He was past president of the American Association for the Advancement of Science, a Senior Advisor to the Directors of the NIH and the NNSA.