Viscous control of cellular respiration by membrane lipid composition
Budin I, de Rond T, Chen Y, Chan LJ, Petzold CJ, Keasling JD. Viscous control of cellular respiration by membrane lipid composition. Science. 2018 Dec 7;362(6419):1186-9.
- Organism: Escherichia coli
- Instrument: 6460 Triple Quadrupole LC/MS
Cells respond to changes in temperature1,2 or chemical additives3,4 by regulating fatty acid synthesis (FAS) in order to maintain a constant viscosity of their lipid membranes5, suggesting that fundamental processes are dependent on this physical parameter. Understanding the functional basis for characteristic physiochemical properties of cellular structures is a major goal of physical biology, but we often lack the capability to systematically modulate such parameters in vivo. Here we investigate functions for unsaturated lipid composition in Escherichia coli using a metabolic engineering approach, which allows us to titrate inner membrane viscosity across a ten-fold range. We find that unsaturated lipids act as tight regulators of E. coli respiration, an effect that is substrate independent and can be mimicked through heterologous synthesis of branched-chain lipids. We introduce a simple physical model to explain these observations, in which membrane viscosity mediates electron carrier (ubiquinone) collisions and reactivity in the Electron Transport Chain (ETC). Numerical simulations of a diffusion-coupled ETC describe several facets of E. coli respiratory activity, providing a quantitative model for respiration in this model system. We propose that the mobility of ETC components serves as a physical constraint for the evolution of lipid composition in energy-transducing membranes.
Created on 6/11/18, 2:58 PM