BII-MCE seminar series
Our semi-monthly seminar series on mechanisms of cellular evolution will feature a mixture of local, national and international speakers that focus on various topics related to evolutionary cell biology. This series will seek to contribute to building a global community of scholars in evolutionary cell biology.
Holly Goodson, PhD
Professor, Department of Chemistry and Biochemistry
University of Notre Dame
What aspects of (cell) biology are predictable?
Is biology predictable? More specifically, are aspects of biology predictable, and if so, which ones? Now is the time to revisit this old and contentious problem because of recent advances in fields including complex systems, synthetic biology and the molecular diversity of life. Questions about the potential predictability of living systems can and should be asked at all biological scales. However, since cells exist at the interface between chemistry and biology, one potentially tractable way to phrase this problem is this: How do physics and chemistry (including geochemistry) lead to predictable cell-level characteristics, such as physical structures, metabolic pathways, and/or information processing networks? In considering these questions, it is important to recognize that when physics and chemistry have been invoked to explain biology, the effect has often been phrased in terms of constraints — that physics and chemistry limit biological systems. However, physics and chemistry can also be profoundly creative; the impact of self-organizing processes is seen at scales from the molecular to the ecological. Addressing the problem of predictability in biology should reveal as-yet unrecognized fundamental principles of biology and help inform other fields of science such as nanotechnology. And, since physics and chemistry are universal, they should provide insight into life as it appears elsewhere in the universe.
Navish Wadhwa, PhD
Assistant Professor, Biodesign Center for Mechanisms of Evolution
Arizona State University
Adaptation to physical stimuli — the case of bacterial flagella
Adaptation is a defining feature of living systems. While cellular adaptation to biochemical stimuli is well studied, how cells adapt to their mechanical environment is poorly understood. I will discuss our attempts to address this gap by studying the flagellar motor, a macromolecular machine that powers swimming in bacteria. This biological nanomachine autonomously adapts to changes in mechanical load by adding or removing force-generating “stator” units. To reveal the physical and molecular mechanisms underlying mechano-adaptation, we used electrorotation, a technique in which a rapidly rotating electric field applies an external torque on single cells. With this method, we could change motor load at will and measure the resulting stator dynamics at high temporal resolution. By combining single-motor experiments with theoretical modeling, we discovered that the force generated by the stator units controls their unbinding, forming a feedback loop that leads to autoregulation of the assembly. Adaptive remodeling of the motor takes place within seconds, making it a highly responsive autonomous control mechanism.