For Whom the Cell Tolls: Regulation of Bacterial Growth and Division by Turgor Pressure

A central goal of systems biology is to elucidate the pathways by which information is communicated within cells in order to control subcellular processes. While research often focuses on genetic and enzymatic pathways, I will highlight three novel paradigms by which microbes use physical factors, including mechanical forces and electric fields, as signals to control cell growth, division, and survival. First, I will describe how Gram-negative bacteria survive and grow robustly during mechanical perturbation by bearing mechanical forces in their outer membrane and by “storing” cell envelope synthesis during perturbation. Next, I will explain how the pathogenic bacterium Staphylococcus aureus harnesses internal hydrostatic pressure to drive sub-millisecond cell division. Finally, I will detail how Gram-positive bacteria use membrane tension and membrane depolarization as signals to ensure balanced synthesis of the plasma membrane and the cell wall. I will conclude by outlining an exciting roadmap for the future study of physical systems biology of microbes, including several questions that follow directly from my present research.