Residues in the pore region of Drosophila transient receptor potential A1 dictate sensitivity to thermal stimuli

Abstract

Key points Transient receptor potential (TRP) A ion channels are evolutionarily conserved and play a fundamental role in thermal, chemical and mechanical transduction. In this study, we characterized Drosophila TRPA1 as a non‐selective cation channel that can be activated by heat, voltage and chemicals. By constructing the chimeric channel between Drosophila TRPA1 and its cold‐sensitive human orthologue, we identified key residues in the transmembrane domain that confer heat sensitivity. Perturbation of the putative voltage‐sensing module increased the threshold for heat activation. Single channel recordings revealed the reaction schemes of wild‐type and mutant channels. Abstract The capacity to sense temperature is essential for the survival of all animals. At the molecular level, ion channels belonging to the transient receptor potential (TRP) family of channels function as temperature sensors in animals across several phyla. TRP channels are opened directly by changes in temperature and show pronounced sensitivity at their activation range. To determine how temperature activates these channels, we analysed channels belonging to the TRPA family, which detect heat in insects and cold in mammals. By constructing chimeric proteins consisting of human and Drosophila TRPA1 channels, we mapped regions that regulate thermal activation and identified residues in the pore helix that invert temperature sensitivity of TRPA1. From analysis of individual channels we defined the gating reaction of Drosophila TRPA1 and determined how mutagenesis alters the energy landscape for channel opening. Our results reveal specific molecular requirements for thermal activation of TRPA1 and provide mechanistic insight into this process.