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. Plants respond to seasonal temperature variation by changing their thylakoid lipid composition, while a more rapid mechanism for short-term heat exposure is required. The emission of the small organic molecule isoprene has been postulated as one such possible rapid mechanism. The protective mechanism of isoprene is unknown, but some plants emit isoprene at high temperature. We investigate the dynamics and structure for lipids within a thylakoid membrane across temperatures and varied isoprene content using classical molecular dynamics simulations. The results are compared with experimental findings for temperature-dependent changes in the lipid composition and shape of thylakoids. The surface area, volume, and flexibility of the membrane, as well as the lipid diffusion, increase with temperature, while the membrane thickness decreases. Saturated thylakoid 34:3 glycolipids derived from eukaryotic synthesis pathways exhibit altered dynamics relative to lipids from prokaryotic synthesis paths, which could explain the upregulation of specific lipid synthesis pathways at different temperatures. Increasing isoprene concentration was not observed to have a significant thermoprotective effect on the thylakoid membranes, and that isoprene readily permeated the membrane models tested.

Automated summary

The thylakoid membrane in plants undergoes temperature-sensitive changes in lipid composition and shape in response to seasonal temperature variation. Isoprene has been proposed as a rapid mechanism for short-term heat exposure, although its protective mechanism is still unknown. Molecular dynamics simulations show that temperature increases the surface area, volume, and flexibility of the membrane, while decreasing its thickness. Isoprene concentration does not have a significant thermoprotective effect on thylakoid membranes.