Fig 2.

An escP mutant EPEC strain secretes reduced levels of translocators and increased levels of effectors. (A) Protein secretion profiles of WT EPEC and the ΔescN mutant strain, the ΔescP mutant strain (−), the ΔescP mutant strain with the empty vector (pTrc99A), and the ΔescP mutant strain expressing plasmid pJTo16 (escP), visualized by Coomassie brilliant blue-stained SDS–15% PAGE (upper panel). Immunodetection of secreted proteins (S) and whole-cell-lysates (P) was performed using anti-EspB, anti-EspA, anti-Tir, anti-EspF, and anti-DnaK antibodies. Densitometry analysis of secreted proteins in Western blot assays was performed using the Scion Image software (Scion Corporation) (B) Profiles of HA-tagged effector NleC, NleD, NleH, NleI, EspH, Map, and Tir secretion by WT and ΔescN and ΔescP mutant EPEC strains. Immunodetection of secreted proteins (S) and whole-cell lysates (P) was performed with anti-HA antibody. Anti-EspC and anti-DnaK antibodies were used as loading controls. The EspC protein is not secreted via the T3SS. Molecular masses of protein standards are indicated on the left of each panel.