FIG 7.

Principles of analyses of effector protein-SLE fusion proteins in infection biology. (A) Genetic fusions between T3SS effector proteins and SLE; for example, HaloTag is expressed by the bacterial pathogen. Fusion proteins are translocated and assume specific subcellular localization in host cells. Ligands are cell-permeable and allow labeling in living infected host cells or within bacteria. After removal of nonbound ligand, labeled effector proteins can be detected by various imaging approaches. (B) Labeling of effector-SLE fusion proteins with ligands in extracellular bacterial cells and translocation into host cells. This approach is applicable to preformed proteins such as SPI1-T3SS effector proteins. (C) Labeling of SLE fusion proteins in infected cells. This approach is applicable to proteins synthesized by intracellular bacteria, such as SPI2-T3SS effector proteins. Representative experimental time lines are given for analyses performed with STM SPI1-T3SS or SPI2-T3SS effector proteins.