Fig. 5.

Structural characteristics of occluded groove conformation in L302A nhTMEM16. a Projection of all the L302A trajectories (purple symbols) onto the 2D tICA landscape of the wild-type system from Fig. 1a. The dynamics of the two subunits of the protein in each trajectory were considered separately in the analysis. The location of the initial conformation of the system (the 4WIS X-ray model) is indicated on the 2D tICA landscape by the yellow circle marked Start. From this configuration, the L302A system evolved towards the microstates denoted by a–c described in the other panels (see also Supplementary Fig. 9). b Structural representation of the initial conformation of the L302A system and of the representative conformations of microstates a, b, and c. In these structural models, the relevant groove residues appear in space fill representations, and are labeled. c The probability distributions of the C_α-C_α distance between V337-V447 residues in microstates a, b, and c. The vertical dashed lines represent the 8.5 Å distance cut-off used to define the occluded conformation of the groove. d Structural superpositions with respect to the X-ray structure of the nhTMEM16 (PDBID: 4WIS; in white), of the groove regions (helices TM3-TM6) from the occluded groove conformation in the WT nhTMEM16 simulations (in blue) and from the L302A simulations (in red). The simulated structures of the wild type and the L302A nhTMEM16 are represented by the centroids of the respective ensemble of conformations (i.e., for the wild type—microstate 3 in Fig. 1a; for the L302A—microstate a in Fig. 5a, b)