FIGURE 8.

The YidC insertase [adapted from Kumazaki et al. (2014b) PDB: 3WVF]. (A) The E. coli YidC has a large periplasmic domain, a coiled cytoplasmic domain, and a conserved core region comprising of 5 TM helices (TMs 2–6) that form a hydrophilic groove open to the cytoplasm and lipid bilayer. The hydrophilic groove has a strictly conserved arginine that helps to keep the region hydrated. (B) A close-up view of the greasy slide (TM3 and TM5) that contacts the TM region of YidC substrates during insertion. The residues that contact the substrate TM segment (s) are indicated in dark blue. (C) During membrane insertion of the Pf3 coat, the TM segment moves up the greasy slide with the N-tail region captured transiently in the hydrophilic groove. The periplasmic domain of YidC is omitted in (B,C).