Unique Substrates Secreted by the Type VI Secretion System of Francisella tularensis during Intramacrophage Infection
Figure 3
Secretion of Francisella beta-lactamases into J774A.1 macrophages.
Macrophages were infected with strains of F. tularensis or F. novicida expressing beta-lactamase genes in cis or trans. After infection, cells were washed and loaded with CCF2/AM and analyzed using live cell microscopy. β-lactamase activity is revealed by the blue fluorescence emitted by the cleaved CCF2 product, whereas uncleaved CCF2 emits a green fluorescence.