The role of electrostatic interactions in the stabilization of main functional states of the bacterial mechanosensitive channel MscS

Abstract

Conformational searches initiated from known crystal and cryo-EM structures have suggested a compact resting state of MscS characterized by “upright” TM1-TM2 pairs and tighter TM2-TM3 contact. Simulated transitions from structures with splayed TM1-TM2 pairs to this compact state point to the importance of several conserved arginine residues. Here, we determine the state-stabilizing contributions of these arginines and evaluate the compact model. We found that R46, R54, and R74 likely stabilize the open state by acting as anchors for TM1-TM2 helices to phospholipids of the inner leaflet.