The Pore Turret of ThermoTRP Channels is a Portable Domain Contributing to Temperature Sensing

Abstract

ThermoTRP channels sense ambient temperature and function as thermosensor, however, the mechanism for sensitive temperature-dependent activation remains unknown. Recent studies point to the outer pore region as an important gating structure. Our previous study shows pore turret moves substantially during temperature-driven activation, which isn’t seen during capsaicin-driven activation. Present research focuses on contribution of pore turret to heat-induced activation using a structural perturbation approach. Partial deletions and sequence replacements are performed with TRPV1 turret. Additionally, the turret is swamped between TRPV1 and TRPV2/TRPV3. All mutant channels exhibit similar capsaicin sensitivity to wildtype TRPV1 with a less than 10-fold shift in EC50, which is consistent with the notion that temperature and ligand activate TRPV1 through different pathways. In contrast, deletion and replacement mutants exhibit activation at a very different temperature, show rapid inactivation during heating, or lose temperature response. Interestingly, TRPV1 chimera containing TRPV3 turret V1/3S behaves like wildtype TRPV3 and activates at a much lower temperature, while TRPV1 chimera containing TRPV2 turret V1/2S activates at a much higher temperature like wildtype TRPV2. These results reveal that pore turret is a portable domain contributing to temperature sensing.View Large Image | View Hi-Res Image | Download PowerPoint Slide