Self-assembly is a fundamental process that drives organization and function across biological systems, spanning molecular complexes to multicellular structures. In this talk, I will present our recent research on the role of self-assembly in actin cytoskeletal dynamics and the evolution of multicellularity. At the molecular scale, our work challenges the classical model of actin treadmilling using advanced single-molecule imaging and force spectroscopy. We have uncovered a complex interplay of molecular components at actin filament ends, where depolymerases, polymerases, and blockers work together to achieve precise spatial and temporal control of filament assembly and remodeling. These findings reshape our understanding of cytoskeletal self-organization, revealing a finely tuned multicomponent system governing filament dynamics. Building on these principles, at the organismal scale, I will discuss how self-assembly may have influenced early multicellular organization in the unicellular protist Stentor coeruleus. Our findings reveal that hydrodynamic coupling between neighboring cells enhances feeding efficiency, with asymmetric benefits favoring specific individuals, potentially driven by proximity or size. This mechanism provides insights into the selective forces that may have driven the transition from unicellular to multicellular life. Together, these studies demonstrate how self-assembly fosters complexity and functional adaptability across scales in biological systems.
Biography:
Dr. Shashank Shekhar is an assistant professor of cell biology, physics and biochemistry at Emory University. His research interests are in biological self-assembly at the molecular and organismal scale. He is the recipient of several awards including the NIH MIRA, Whitman Early Career Award from the Marine Biological Laboratory and the Grand advances in Biology Prize from the French Academy of Sciences. He was also recently named a “Cell Scientist to Watch” by the Journal of Cell Science. He received his PhD in experimental cell biophysics from University of Twente (The Netherlands). He earned his master’s in Nanoscience and Molecular Bioengineering from TU Delft (Netherlands) and TU Dresden (Germany) and undergraduate degree in Physics in India.