IISER MOHALI

Abstract: Actin is an essential protein. For over four decades, intracellular actin filaments have beenthought to elongate at their barbed ends and depolymerize from pointed ends. This process,referred to as “treadmilling” has formed the central bedrock of our understanding of actindynamics. Using a combination of microfluidics-assisted TIRF imaging and multispectral singlemolecule approaches which my lab has pioneered, our recent discoveries have called intoquestion the universality of the treadmilling dogma. First, we recently discovered a new actindepolymerase, twinfilin, which induces depolymerization at filament barbed ends. Interestingly,we find that the depolymerase twinfilin, polymerase formin and blocker CP form amulticomponent protein ecosystem at the filament ends. Together, these proteins allowtemporal and spatial tuning of actin assembly and remodeling. Second, I will present ourdiscovery of a new actin polymerase VopF, which processively polymerizes actin filaments fromtheir pointed ends. Our findings thus challenge the classical dogma of actin treadmilling and callfor reevaluation of molecular mechanisms governing intracellular actin dynamics.\n\nBiography: Dr. Shashank Shekhar is an assistant professor of cell biology, physics and biochemistry atEmory University. His research interests are in biological self-assembly at the molecular andorganismal scale. He is the recipient of several awards including the NIH MIRA, Whitman EarlyCareer Award at the Marine Biological Laboratory and the Grand advances in Biology Prizefrom the French Academy of Sciences. He received his PhD in experimental cell biophysicsfrom University of Twente (The Netherlands). He earned his master’s in Nanoscience andMolecular Bioengineering from TU Delft (Netherlands) and TU Dresden (Germany) andundergraduate degree in Physics in India.\n\nTea/Coffee Time: 5 PM\n\n