ION CHANNEL THERMODYNAMICS STUDIED WITH TEMPERATURE JUMPS MEASURED AT THE CELL MEMBRANE

Perturbing the temperature of a system modifies its energy landscape thus providing a ubiquitous tool to understand biological processes. Here, we developed a framework to generate sudden temperature jumps (Tjumps) and sustained temperature steps (Tsteps) to study the temperature dependence of membrane proteins under voltage-clamp, while measuring the membrane temperature. Utilizing the melanin under the Xenopus laevis oocytes membrane as a photothermal transducer, we achieved short Tjumps up to 10 {o}C in less than 1.5 ms and constant Tsteps for durations up to 150 ms. We followed the temperature at the membrane with submillisecond time resolution by measuring the time-course of membrane capacitance, which is linearly related to temperature. We applied Tjumps in Kir 1.1b, which reveals a highly temperature-sensitive blockage relief and characterized the effects of Tsteps on the temperature-sensitive channels TRPM8 and TRPV1. These newly developed approaches provide a general tool to study membrane proteins thermodynamics.