Mechanosensitive PIEZO channels are thought to open via tension-induced flattening of peripheral transmembrane arm domains, yet the structural basis of this activation remains unclear. Here, by leveraging hybrid-resolution molecular dynamics simulations, we uncover how large-scale PIEZO2 arm movements funnel into subtle gating motions in the central pore under physiological tension. Arm flattening correlates with anticlockwise rotation of the pore relative to the arms and with clockwise twisting of inner pore helices. These clockwork motions open the pore in a two-step fashion, yielding a fully conducting state and a stable subconducting state populated at a low tension, which was detected electrophysiologically. The fully open PIEZO2 pore is walled by both lipids and amino acids and recapitulates minimal pore size, conductance, ion selectivity and outward rectification of chloride currents measured electrophysiologically. These findings provide structural insights into PIEZO2 gating and demonstrate hybrid-resolution molecular dynamics as a powerful approach to study large-scale membrane protein dynamics and guide drug discovery.
Li et al. (Tue,) studied this question.