FIG. 2.

Expression of yscP-gst blocks needle formation in wild-type Y. enterocolitica. (A) Wild-type (WT) Y. enterocolitica expressing gst, yscP-gst, and yopR-gst was grown in the absence (−) and presence (+) of the inducer IPTG, and following centrifugation of culture aliquots, proteins in the supernatant (S) and pellet (P) were separated by SDS-PAGE, transferred to PVDF membranes, and probed with antisera to YscF, LcrV, YopE, and chloramphenicol acetyltransferase (CAT) or NPT. (B) Needles were purified from the cultures in panel A, and the purified needle preparations were separated by SDS-PAGE, transferred to PVDF membranes, and probed with antisera to YscF and LcrV. (C) Purified needle preparations from the strains in panel A were immobilized on carbon-coated copper grids. Samples were negatively stained with 2% uranyl acetate and viewed by transmission electron microscopy. The bars indicate a distance of 10 nm.