Abstract: Prominent among biophysical techniques is the optical trap, for which Arthur Ashkin (Bell Labs) received a Nobel Prize in 2018. Among the successes of optical traps have been direct measurements of the steps taken by biological motor proteins, such as kinesin, and by nucleic-acid enzymes, such as RNA polymerase. Optical traps facilitate studies of replication, transcription, and translation at the single-molecule level. They’ve been especially useful in mapping the free-energy landscapes of folding by small, structured RNAs. It’s even proved possible to monitor folding co-transcriptionally, as RNAs get synthesized, revealing how folding dynamics regulate gene expression. Optical traps can be used in conjunction with single-molecule FRET to report simultaneously on folding intermediates and internal degrees of freedom within structured RNAs. This review talk will offer a historical perspective on studies carried out in my laboratory over the past 30 or so years.
Bio: Steven M. Block is the S.W. Ascherman Professor of Sciences, emeritus, in the Departments of Applied Physics and of Biology at Stanford University. He received his B.A. and M.A. from Oxford University and his Ph.D. from Caltech. Block has been elected to the National Academy of Sciences and the American Academy of Arts and Sciences. He is a Fellow of the American Physical Society, a Fellow of the Biophysical Society, and Fellow of the American Association for the Advancement of Science. He was awarded the Delbrück Prize in Biological Physics of the APS and the Benjamin Franklin Medal of the Franklin Institute, among other academic recognitions. Block’s research lies at the interface of physics and biology, particularly in the study of enzymes and nucleic acids at the single-molecule level. His group pioneered the development of the laser-based optical trap (“optical tweezers”) to study biomolecules, and was the first to measure the fundamental steps taken by motor proteins, including the 8.2-nm steps of kinesin, a cellular transporter, and the 3.4-angstrom (basepair) steps of RNA polymerase, the enzyme responsible for gene transcription. His research focuses on understanding the biomolecular mechanisms responsible for movement, fidelity, folding, and ligand binding.
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