FIG. 7.
The stability of YopE controls the translocation levels of other Yop effectors. Reverse regulation of intracellular levels of YopH and YopP by YopE is shown. (A) HEK293 cells were left untreated (φ) or infected with yersiniae producing either wild-type YopE (WA and WA-YopEwt) or K62- and K75-mutagenized YopE O8 (WA-YopEK62R/K75Q). (B) The cells were additionally treated with the proteasome inhibitor MG-132 where indicated. (C) Yersinia mutants defective for YopP (WA-ΔyopP) or YopE (WA-ΔyopE) were additionally used. (D) YopE-deficient WA-ΔyopE was complemented either with wild-type YopE O9 (WA-ΔyopE/YopE-O9wt) or with YopE O9 harboring lysines instead of R62 and Q75 (WA-ΔyopE/YopE-O9R62K/Q75K). Cellular lysates for all panels were prepared 3.5 to 4 h after onset of infection, and the amounts of Yops in the lysates were determined by immunoblotting with the respective anti-Yop antibodies. Equal loading of the gels with cell lysates was controlled by reprobing the membranes with antiactin antibody. A possibly unspecific band appears below YopP in panel A.