Figure 3. Structure of the T4P machinery in the closed state.
(A and B) Tomographic slices of T. thermophilus cells show large protein complexes crossing the periplasm in the absence of pili (white arrowheads). Scale bars = 100 nm. (C) Resulting subtomogram average (left panel) and its 2D projection (centre) are compared to the previously determined projection map of isolated and stained PilQ (right panel) (Burkhardt et al., 2011). The contrast of the stained PilQ has been inverted. This image was originally published in The Journal of Biological Chemistry. Janin Burkhardt, Janet Vonck, and Beate Averhoff. Structure and Function of PilQ, a Secretin of the DNA Transporter from the Thermophilic Bacterium T. thermophilus HB27. JBC. 2011; 286:9977–9984, the American Society for Biochemistry and Molecular Biology. The putative N0–N5 domains of PilQ (Burkhardt et al., 2012) are marked. (D) 3D surface rendering of the average reveals that PilQ has a periplasmic vestibule closed at both ends by two gates. Additional protein densities distinct from PilQ (green arrowheads; C1 = proximal to the cytoplasmic membrane, P1 = central periplasmic ring 1, P2 = central periplasmic ring 2) are also shown. OM, outer membrane; PG, peptidoglycan; CM, cytoplasmic membrane.
Figure 3—figure supplement 1. Fourier shell correlation curves for subtomogram averages.
