Fig 6. Visualization and characterization of the pore formed by SpaP and SpaR.

(A) Six selected class averages (4, 23, 29, 36, 55, 82) of negative-stained isolated SpaPR complexes imaged by electron microscopy. The length of the scale bar represents 50 Å. The two class averages at the top represent the SpaP₅ complex. Arrowheads in the class averages in the middle and at the bottom represent the anticipated position of SpaR on the SpaP₅ ring. The complete picture of all class averages can be seen in S4 Fig. (B) Fluorescent streptavidin detection of SDS PAGE-separated biotin maleimide-labeled proteins of whole cell lysates, cell culture supernatant, periplasmic fraction, or cytoplasmic fraction of S. Typhimurium ΔprgHIJK, flhD::tet moderately overexpressing indicated proteins from a medium copy number plasmid (pT12). (C) Blue native PAGE and immunodetection of a high molecular weight complex formed by EPEA-tagged SpaP alone.