Nanoscale Simulation of the Thylakoid Membrane Response to Extreme Temperatures

The thylakoid membrane is in a temperature-sensitive equilibrium that shifts repeatedly during the life cycle in response to ambient temperature or solar irradiance.<br> Plants respond to seasonal temperature by changing their thylakoid lipid composition, while a more rapid mechanism for short-term heat exposure is required.<br> The emission of the small organic molecule isoprene has been postulated as one such possible rapid mechanism.<br> The protective mechanism of isoprene is not known, but some plants emit isoprene during periods of high-temperature stress.<br> In this work, we investigate the dynamics and structure for lipids within a thylakoid membrane at different temperatures and varied isoprene content using classical molecular dynamics simulations.<br> The results are compared with experimental findings from across the literature for temperature-dependent changes in the lipid composition and shape of thylakoids.<br> We find that the surface area, volume, and flexibility of the membrane, as well as the lipid diffusion, increase with temperature, while the membrane thickness decreases.<br> Saturated thylakoid 34:3 glycolipids derived from eukaryotic synthesis pathways exhibit significantly different dynamics than lipids from prokaryotic synthesis paths, which could explain the upregulation of specific lipid synthesis pathways at different temperatures.<br> Increasing isoprene concentration was not observed to have a significant thermoprotective effect on the thylakoid membranes.