Figure 1. Schematic of Sec-mediated cotranslational integration of EmrE and corresponding simulation representation.
(A) At top, an illustration of the structural motifs in EmrE, including indication of the charged residues in the soluble loops with black circles and the transmembrane domain (TMD)/loop numbering scheme that is employed in the text; below, the corresponding sequence of coarse-grained (CG) beads that represent the EmrE amino-acid sequence. TMDs and loops are assigned based on the hydropathy plot and consensus topology prediction shown in Figure 1—figure supplement 1. (B) At top, a schematic illustration of the sequential integration of TMDs to obtain a multispanning Nperi/Cperi topology, in which both the N- and C-terminal loops are positioned in the periplasm, according to the cotranslational model; below, representative simulation snapshots of EmrE as the nascent protein grows during translation, integrates into the membrane, and exits the channel in the Nperi/Cperi multispanning topology. The nascent protein is colored according to the legend at top, the ribosome is brown, and the translocon is green with translocon charges labeled explicitly.
Figure 1—figure supplement 1. Hydropathy plot for EmrE.
Figure 1—figure supplement 2. Simulation snapshot illustrating the initial configuration comprised of 9 CG beads.
